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SOIL SEED BANK DYNAMICS IN
TRANSFERRED TOPSOIL EVALUATING RESTORATION POTENTIALS
William M. Fowler
Thanks to my supervisors Dr. Joe Fontaine and Prof. Neal Enright for all the advice and support given over the last year. I would also like to thank the members of the Murdoch University, Terrestrial Ecology Research Group (TERG) for their valuable assistance and guidance, especially Willa Veber and Dr. Philip Ladd, as well as the Murdoch University Environmental Science Association (MUEnSA) for helping find enthusiastic volunteer field assistants. I wish to thank the Department of Environment and Conservation (DEC) for providing technical and financial assistance in addition to information and resources that were vital to this projects success. Finally I would like to thank the Environmental Weeds Action Network (EWAN) for awarding me a scholarship to help me complete this valuable research.
Bachelor of Science in Environmental Science and Environmental Restoration
School of Environmental Science
October 2012
Acknowledgements
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DECLARATION
I declare that this thesis is my own original work and has not been submitted for any
other unit for academic credit.
William Michael Fowler
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ABSTRACT
Global change, increasing human population growth and urbanisation represent
increasing pressures on biodiversity and ecosystem function. It is now widely
recognised that conservation of existing natural fragments will not be sufficient to
maintain extant biodiversity or meet conservation goals. Thus there is a major and
rapidly expanding need for the practice of ecological restoration whereby degraded
lands are managed to increase and maintain indigenous species.
A soil seed bank germination experiment was conducted over a period of 13
weeks. This aimed to evaluate restoration values of topsoil transfer, by investigating soil
seed bank similarity to standing vegetation, and exploring mechanisms to improve
restoration outcomes on the Swan Coastal Plain, Western Australia. This was
experimentally designed to make comparisons between the soil seed bank pre and post-
transfer, an aspect of topsoil transfer that has not been looked at previously. In addition
sampling was conducted at two depths, with treated (smoke and heat) and non-treated
trials. This study examined the similarity of the soil seed bank to standing vegetation,
the effect of soil transfer, and the influence of soil spreading depth and fire related
germination cues.
Seventy-three per cent of germinants were found in the top 5 cm of natural (pre-
transfer), soil transfer leading to mixing (no depth effect) and a reduction in germinant
densities (-2472.00 germinants m-2). Treatment with germination cues (heat and smoke
in concert) increased germinant densities by 1537.80 germinants m-2, however no
increase in transferred soils was observed. Native annuals dominated species
composition of transferred soils, contributing 68% of observed richness, with woody
species only accounting for 9% overall. The similarity of the soil seed bank to the
standing vegetation ranged from 15% to 19%, the higher similarity found when
treatment was used. Overall topsoil transfer is a useful tool for restoration; however it
must be used in conjunction with other methods, such as planting and direct seeding, to
return a representative set of species to a site.
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TABLE OF CONTENTS
DECLARATION .................................................................................................................. II
ABSTRACT ....................................................................................................................... III
TABLE OF CONTENTS ....................................................................................................... IV
LIST OF FIGURES .............................................................................................................. VI
LIST OF TABLES .............................................................................................................. VII
CHAPTER 1 – INTRODUCTION ........................................................................................... 1
1.1 RESEARCH AIMS ............................................................................................................. 5
1.2 THESIS OUTLINE ............................................................................................................. 6
CHAPTER 2 – STUDY AREA AND METHODS ........................................................................ 7
2.1 STUDY SETTING .............................................................................................................. 7
2.2 FIELD SAMPLING AND DATA COLLECTION ............................................................................... 9
CHAPTER 3 – RESULTS .................................................................................................... 18
3.1 SEED BANK DYNAMICS ................................................................................................... 18
3.2 SIMILARITY .................................................................................................................. 27
3.3 COMMUNITY ANALYSIS .................................................................................................. 27
CHAPTER 4 - DISCUSSION ............................................................................................... 31
4.1 INFLUENCE OF DEPTH OF TOPSOIL ON RESTORATION OUTCOMES ............................................... 31
4.2 THE EFFECT OF TOPSOIL TRANSFER ON GERMINANT COMPOSITION ............................................ 34
4.3 GERMINATION SIMULATION WITH COMMON GERMINATION CUES ............................................. 34
4.4 SOIL SEED BANK AND ITS RELATIONSHIP TO THE STANDING VEGETATION ..................................... 35
CHAPTER 5 – CONCLUSIONS AND RECOMMENDATIONS .................................................. 38
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5.1 CONCLUSIONS .............................................................................................................. 38
5.2 RECOMMENDATIONS FOR MANAGEMENT OF TOPSOIL TRANSFER ON THE SWAN COASTAL PLAIN ...... 38
5.3 RECOMMENDATIONS FOR FUTURE RESEARCH ....................................................................... 39
REFERENCES .................................................................................................................. 40
APPENDICES .................................................................................................................. 50
APPENDIX A – STATISTICAL SUMMARIES OF ALL NORMAL PARAMETRIC ANALYSIS ............................... 50
APPENDIX B – SPECIES LISTS ................................................................................................. 51
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LIST OF FIGURES
Figure 1 – Diagramatic representation of the change in seed gradient as a result of mixing due to the
transfer process. ........................................................................................................................ 5
Figure 2 – Site locations relative to Perth, Western Australia. The cross indicating the location of
Jandakot Airport from which soil was striped. Triangles indicating the recipient sites of
Forrestdale Lake and Anketell RD. Adapted from the Nokia map service (Nokia 2012). ............ 8
Figure 3 - Position of transects and plots at Jandakot Airport. The area which soil was stripped from
is enclosed by the solid black lines. Plots are represented by the dots; with series of dots
forming transects which are labelled accordingly. ................................................................... 10
Figure 4 - Main: Image of the loader used to harvest topsoil from Jandakot Airport by Urban
Resources. Insert: side view of the wing-like bucket modifications used to prevent over
harvesting of topsoil. ............................................................................................................... 11
Figure 5 – Site and plot locations at Forrestdale Lake. Dots representing plots, clustered in the deep
areas of transferred soil at the three smaller sites within the greater area of Forrestdale Lake
(Nature Reserve). .................................................................................................................... 11
Figure 6 – Site and plot locations and Anketell Road. Dots representing plots, clustered in the deep
areas of transferred soil at the three smaller sites within the greater Anketell Rd site. ........... 12
Figure 7 - Diagram of the soil sampling tube (not to scale) used for sampling topsoil in this study. . 12
Figure 8 – Sampling arangement within each plot (not to scale), the circles representing the
locations of soil samples which were composited. .................................................................. 12
Figure 9 – Diagram of seeding marking procedure, bands indicating colour code progression as
identification became more developed. .................................................................................. 15
Figure 10 – Proportion of total germinants the study over time (weeks). ........................................ 18
Figure 11 – Mean germinants m-2
by treatment across depth and site. ............................................ 19
Figure 12 – Mean species richness by treatment across depth and site. .......................................... 20
Figure 13 – Diversity using the Shannon-Wiener index, by treatment across depth and site. .......... 21
Figure 14 – Mean germinants m-2
by treatment, across depth and site, comparing growth forms. .. 22
Figure 15 – Mean germinants m-2
of invasive species and native species split into longevity
categories, across treatment and depth (unknown species removed). .................................... 23
Figure 16 – Density of native perennial species and their proportion of woody and non-woody. .... 25
Figure 17 – Density of germinants m-2
of seeders and resprouters across treatments, depths and
sites. ........................................................................................................................................ 26
Figure 18 – Mean density germinants m-2
of categories of Proteoid roots (0=0, 1=0-25%, 2=25-50%,
3=50-75%, 4=75-100%). ........................................................................................................... 26
Figure 19 – Ordination of all trays using NMS. Axis 1 correlated with site, from transfer to natural.
Axis 2 correlated with depth, 5-10cm to 0-5cm. ...................................................................... 28
Figure 20 – Panel of three joint plot analyses, with correlations. A – Growth form and invasive
status, B – Richness and diversity, C – species. Only those vectors with r2 values > 0.20 are
displayed. ................................................................................................................................ 29
Figure 21 – Graphical representation of the potential influence of compaction in the soil stripping
process. Effect of over harvesting is for illustrative purposes only........................................... 32
Figure 22 – Photo of proteoid roots on site at Jandakot Airport. ...................................................... 33
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LIST OF TABLES
Table 1 – Criteria used by DEC and their relative importance in recipient site selection. Adapted
from Brundrett (2012). .............................................................................................................. 9
Table 2 – Ranking system for the allocation of cover rankings consistent with Braun-Blanquet
(1932). ..................................................................................................................................... 10
Table 3 - Top 5 species by abundance for each treatment on natural and transferred soils. Blanks
indicate that the species was not in the top 5 most abundant for that treatment. .................. 24
Table 4 – Average number of species found in the soil seed bank (SSB) and above ground vegetation
(AGV), and the average similarity between the SSB and AGV, using Sorenson’s similarity index.
................................................................................................................................................ 27
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CHAPTER 1 – INTRODUCTION
Ecological restoration is of vital importance in a world of rapid human
population growth and development, and consequent degradation of the natural
environment. Simply conserving the remaining natural areas is no longer sufficient to
meet current goals (Grimm et al. 2008; McCarthy et al. 2012). Ecological restoration can
be defined broadly as the process of assisting the recovery of an ecosystem that has
been degraded, damaged or destroyed (SER 2004). As biodiversity conservation
becomes ever more important on a global scale, restoration is being used increasingly as
a tool to offset the ecological impacts of development (CBD 2010; Hobbs et al. 2011;
McCarthy et al. 2012). Offsets in restoration may occur through physically restoring an
area to its pre-disturbance state, or by securing and restoring new areas for
conservation (Gardner and Bell 2007; Hobbs et al. 2011). Restoration has the potential
to be misguided, under the expectation that ecosystems can be completely restored,
which may not always be a realistic goal (Gardner and Bell 2007; Hobbs 2007; Hobbs et
al. 2011). Ecological restoration is a relatively new science, and thus requires more
research in order to understand its complexities, and to create better outcomes for
biodiversity conservation in the future.
Increasing pressure on natural areas drives the need for ecological restoration.
Expansion of the built environment is having detrimental effects on natural areas,
through bushland clearing and fragmentation, altering of chemical and physical
dynamics and loss of biodiversity (Folke et al. 2004). It is these natural areas which are
vital for species as either habitat, feeding grounds, for ecological linkages and to provide
ecosystem services (Loreau et al. 2001; Grimm et al. 2008; Palmer and Filoso 2009).
Restoring biodiversity can also create greater resilience to future disturbance as well as
enhance ecosystem function (Loreau et al. 2001; Folke et al. 2004). In addition to
ecological benefits, restoration can return many other values to the landscape, including
personal, socioeconomic and cultural values (Clewell and Aronson 2007).
A broad range of techniques are used to restore areas of degraded vegetation,
most often involving two distinct methods, the planting of nursery-raised seedlings and
direct seeding using seed mixes of desired native species. Topsoil transfer, the process
of moving topsoil containing dormant but viable soil stored seeds of native plants –
potentially in high quantities – is a relatively recent method employed to enhance
restoration success, and is playing an increasing role in the restoration of ecosystems
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(Tacey, Olsen, and Watson 1977; Engel and Parrotta 2001; Skrindo and Pedersen 2004;
Ralph 2006; Tozer et al. 2012). Direct planting is characterised by relatively high
survivorship but can be expensive and is limited to those species available from
commercial nurseries (Engel and Parrotta 2001; Viani and Rodrigues 2009). Direct
seeding can be done mechanically on a large scale or by hand, but is generally
considered to have a high mortality compared to planting, and is most feasible in areas
receiving over 250 mm rainfall per year (Ackzell 1993; Knight, Beale, and Dalton 1998;
Engel and Parrotta 2001). It is also expensive, since seeds must be collected for each
species, which may vary in their timing and abundance of seeding, and in their
germination requirements, so that their ability to be restored via these methods is
limited (Ralph 2006; Sweedman and Brand 2006; Koch 2007b). Topsoil transfer has
several benefits over these methods, in particular over direct seeding (Fry 2011). The
soil itself can suppress the potential weedy underlying soil which could limit the success
of planting and seeding. Moving topsoil can also transfer beneficial soil microbes and
other propagules of species not able to be restored readily by other methods (Jasper
2007; Koch 2007b). The use of soil seed banks through topsoil transfer is increasingly
common in restoration because of its benefits over other methods (Howard and Samuel
1979; Koch 2007b; Tozer et al. 2012).
Most of the world’s plant communities produce some form of soil seed bank, and
it is these seed banks that are an important part of a functioning ecosystem (Harper
1977; Bell 1999). Mature seed is shed from the parent plant to the soil surface, and
accumulation of these seeds over time develops a soil seed bank comprising seeds which
may be able to remain dormant for many years (Bell, Plummer, and Taylor 1993; Baskin
and Baskin 1998; Fenner and Thompson 2005; Keith 2012).
There are two broad categories of soil stored seed, transient seed banks, those
that persist for less than a year, and persistent seed banks, which persist for longer
periods of time (Fenner and Thompson 2005). This is an important distinction because
transient seed banks tend to be those that germinate immediately or seasonally, while
those that persist for longer periods are dormant until they receive an appropriate
trigger (Merritt and Rokich 2006). Triggers are related to disturbance or opportunity,
whereby either light is received to the understory or a more widespread disturbance
such as fire enables plant propagules stored in the soil to take advantage of a lack in
competition. However, not all species contribute equally to the soil seed bank. For
example, serotiny (canopy stored seed) is used by some species, and is commonly seen
in the Mediterranean regions of Western Australia and South Africa (Lamont et al.
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1991). Resprouting (tending not to produce high amounts of seed) is also a trait
exhibited in species which results in little contribution to the soil seed bank (Lamont et
al. 1991). Soil seed banks as a result are highly variable in composition and seed density
both locally and globally depending on the ecosystem type, species present and time
since disturbance (Hopfensperger 2007).
Depth, heat and smoke cues are important factors in enabling germination from
soil seed banks in fire-prone environments. Seed density in soil declines with depth,
with most seeds close to the soil surface, those buried at depths greater than a few
centimetres generally failing to germinate (Bellairs and Bell 1993; Brown, Enright, and
Miller 2003; Fenner and Thompson 2005; Luzuriaga et al. 2005; Merritt and Rokich
2006; Fisher et al. 2009). Many seeds in the soil seed bank lie dormant until a
germination cue such as smoke and/or heat occurs. Without such a cue to stimulate
germination, many seeds will not germinate easily (Bell, Plummer, and Taylor 1993; Bell
1999). In fire-prone environments, the chemicals in smoke have been found to be a key
component in triggering germination (Keeley and Keeley 1987; De lange and Boucher
1990; Dixon, Roche, and Pate 1995; Roche, Koch, and Dixon 1997; Smith, Bell, and
Loneragan 1999; Rokich and Dixon 2007; Tozer et al. 2012). Heat is also a common
trigger in many hard-seeded species, due to scarification, or damage of the seed coat
that results from heat exposure (Bell, Plummer, and Taylor 1993; Baskin and Baskin
1998; Enright and Kintrup 2001; Merritt and Rokich 2006). The combination of heat and
smoke together is increasingly seen as the most effective means to illicit germination
across a range of species in such environments (Keith 1997; Blank and Young 1998;
Smith, Bell, and Loneragan 1999; Thomas, Morris, and Auld 2003; Merritt and Rokich
2006; Lindon and Menges 2008).
Seed density is one of the defining characteristics of soil seed banks. Variations
in density can be found between regions and ecosystem types, and are also influenced
by the ecology of the system, including plant functional traits. Much of the global
research into soil seed banks has been undertaken in temperate Mediterranean
environments. For example: the soil seed banks of the Fynbos shrublands of South
Africa range from 1100-1900 seeds m-2 (Holmes and Cowling 1997). Densities of 1050-
1802 seeds m-2 are reported from a heathland environment in Spain (Valbuena and
Trabaud 2001). The northern Jarrah forest of South-West Australia has been seen to
have seed densities of between 377-1579 seeds m-2 (Vlahos and Bell 1986). Tropical
Rainforests in comparison have generally lower densities 88-694 seeds m-2 (Martins and
Engel 2007; Dainou et al. 2011). Soil seed stores in Mediterranean environments thus
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tend to contain higher amounts of seed that can be utilised for restoration by methods
such as topsoil transfer. However, even within Mediterranean environments plant
functional traits can influence seed density. For instance a vegetation community near
Eneabba, Western Australia, is dominated by serotinous and resprouter species, as such
much lower soil seed densities of 140-174 seeds m-2 (Bellairs and Bell 1993) have been
observed.
Banksia woodland of South Western Australia is a high biodiversity ecosystem
and represents an ecosystem of serious conservation concern (Myers et al. 2000; Rokich
and Dixon 2007). This research project focuses on topsoil transfer as a method for
restoration of Banksia woodland on the Swan Coastal Plain (SCP) of Western Australia.
The Banksia woodlands sit within a biodiversity hotspot, characterised by high richness
and endemism, with 79.2% of the vascular plant species and 21.9% of animal species
endemic to the region (Myers et al. 2000; Paczkowska and Chapman 2000). Within this
hotspot, Perth is a rapidly expanding city resulting in the fragmentation and degradation
of the natural landscape (Ramalho and Hobbs 2012). Continued land clearing,
fragmentation, and degradation results in increased pressure on species requiring
natural vegetation for feeding and roosting habitat, such as Carnaby’s Cockatoo
(Calyptorhynchus latirostris) which is listed as ‘Endangered’ under the Environmental
Protection and Biodiversity Conservation Act 1999 (Cwlth) (Valentine et al. 2011). As a
whole, the South West of WA now only retains 10.8% of its original extant of vegetation.
Within this, the Banksia woodland ecological community is listed as endangered, making
restoration important in this setting to help conserve this community type (Myers et al.
2000; SEWPC 2009).
As the process of topsoil transfer is likely to be used increasingly as an offset to
clearing established vegetation communities for urban development or mining, it is
important for research of this kind to be conducted. Little published, peer-reviewed
research exists on the optimisation of topsoil transfer for restoration purposes
throughout the world. What little research has been carried out has predominantly been
undertaken in Western Australia (Vlahos and Bell 1986; Koch et al. 1996; Ward, Koch,
and Ainsworth 1996; Koch, Ruschmann, and Morald 2009). Alcoa World Alumina
(Alcoa) are the primary drivers of this research for mine site rehabilitation on the
lateritic soils of the Darling Plateau, east of Perth (Koch 2007a). This study on the SCP is
therefore innovative in that it tests the impacts of the transfer process on soil seed bank
properties relating to Banksia woodlands, and the value this process may hold for
restoration and management in the future. Potential applications of this study include
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the optimisation of procedures and practices of restoration using topsoil transfer, while
also adding to our knowledge of the world’s soil seed banks in different environments. It
is vitally important for the preservation of Western Australia’s unique but threatened
native vegetation that this process is examined in detail, as many of our native plant
species are not currently able to be propagated by any other means (Rokich et al. 2000).
1.1 RESEARCH AIMS
This thesis examines the soil seed bank composition of undisturbed topsoil from a
natural bushland and compares it with the same soil after it has been removed,
transported, and spread at another site in the topsoil transfer process. The aim is to
establish in general terms how successful topsoil transfer is and how it could be more
successful through examining the following specific questions:
1. HOW DOES DEPTH OF TOPSOIL APPLICATION INFLUENCE RESTORATION OUTCOMES?
This research question examines the seed density by depth in the soil seed bank
both pre and post-transfer. Transfer involves stripping a depth of soil greater than
where the bulk of seeds are situated, therefore this may cause dilution of the seed
density of the soil that has been transferred (Figure 1). This may affect the germination
within the transfer sites when compared to the undisturbed bushland since many seeds
previously near the soil surface will now be buried too deep for germinants to grow
through the soil surface. This is important to potentially maximise restoration outcomes,
and because the amount of soil transferred affects the cost of transportation. Alcoa for
instance has used sieving of seed from soil to concentrate seed density and so reduce the
transportation component, however this does also remove small seeded species (Rokich
and Dixon 2007).
Figure 1 – Diagramatic representation of the change in seed gradient as a result of mixing due to the
transfer process.
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2. WHAT EFFECT DOES THE TRANSFER PROCESS HAVE ON GERMINANT COMPOSITION?
The effects of the soil transfer process need to be examined more closely. In this
study trials are conducted both pre-transfer and post-transfer; this is an aspect that has
not been researched elsewhere. The rationale of this part of the study is that the
physical act of transferring the soil may have an influence on the germination ability of
the soil in either a positive or negative way. The process of topsoil transfer may lead to
the physical scarification of seeds within the seed bank, which could mitigate the need
for other germination treatments. Scarification, a physical germination trigger,
combined with smoke and heat treatment should provide enhanced germination of hard
seeded species, as a result the above procedure will be duplicated at the transfer site to
examine the effects of transfer (Baskin and Baskin 1998; Merritt and Rokich 2006).
3. DOES TREATMENT WITH FIRE RELATED CUES ENHANCE GERMINATION SUCCESS?
Treatments with heat and smoke in combination have been conducted to replicate
fire disturbance, considered a vital trigger for seed germination in many species,
especially in SW Australia (Wills and Read 2002). Smoke and heat treatments together
maximise the dormancy breaking effect and subsequent germination response. A
control treatment using watering only was conducted for comparison purposes (Pierce,
Esler, and Cowling 1995; Read et al. 2000; Merritt and Rokich 2006).
4. HOW REPRESENTATIVE IS THE SOIL SEED BANK TO STANDING VEGETATION?
Certain species of the Banksia woodland community will not be present in the soil
seed bank due to being resprouters or serotinous in nature; this includes the dominant
canopy genus, the Banksias (Wills and Read 2007). Previously it has been found that 60-
80% of the species of the Banksia woodland can store their seed in the soil (Rokich and
Dixon 2007). It is important to examine the species composition of the species that are
present in the soil seed bank, and how these relate to the standing vegetation of high
quality bushland sites, as this is the reference for restoration.
1.2 THESIS OUTLINE
This thesis is organised into 5 chapters. Chapter 2 provides details of the study
area and the methods used to answer the stated research questions. Chapter 3 presents
the results. An in depth discussion of these results is provided in Chapter 4, and
conclusions and recommendations for future topsoil transfer projects are presented in
Chapter 5.
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CHAPTER 2 – STUDY AREA AND METHODS
2.1 STUDY SETTING
The climate of SW Australia is Mediterranean with hot, dry summers and mild,
wet winters (BOM 2012). Annual mean rainfall is 869 mm, 80% of this falling between
May and September, with the summer (December through February) average being 36
mm. Temperatures in summer average 31°C maximum and 17°C minimum, while over
winter, maximum and minimum temperatures average 18°C and 8°C respectively (BOM
2012). A sustained decrease in annual rainfall has been documented since the mid-
1960s with a 23 mm drop per decade (based on 1950-2005 records) (Timbal, Arblaster,
and Power 2006; Gallant, Hennessy, and Risbey 2007). Since the 1970s mean annual
temperature has increased by an average of 0.15°C per decade (Bates et al. 2008).
Climate predictions include continued drying of 15-160 mm and warming of 0.4-2.0°C
by 2030, relative to 1990 (Hughes 2003).
Study sites, Jandakot Airport (from which the topsoil was taken), Forrestdale
Lake and Anketell Rd (where topsoil from Jandakot Airport was received), were located
approximately 20 km south of Perth, Western Australia on the SCP (Figure 2). The SCP is
characterised by sandy soils of varying ages with north-south strips of similarly aged
soils, increasingly old and leached at increasing distances from the Indian Ocean (Powell
2009). Soils at the study sites are classified as Bassendean sands; Aeolian in origin and
pale grey to faint yellow in colour. These are the oldest soils on the SCP, originating in
the middle Pleistocene, around 800,000 years ago (McArthur 1991; Bolland 1998). Due
to their age, minerals and nutrients have been largely been leached, making these soils
quite infertile (Powell 2009).
The extant vegetation of the Jandakot Airport site was remnant Banksia
woodland, a unique vegetation community to the SCP. This vegetation type is dominated
by a tree layer comprising of Banksia attenuata, B. menziesii, B. ilicifolia, Eucalyptus
marginata, E. todtiana and Nuytsia floribunda, with a dense understory of shrubs, herbs,
sedges and rushes (JAH 2009). As with many of Perth’s remnant bushland areas, the site
at Jandakot airport has been isolated by urbanisation, and as such there has been little
influence of fire in the recent past and there is evidence of weed invasion, especially
concentrated at the edges (Fowler pers. obs.).
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Transfer sites, Forrestdale Lake and Anketell Rd, were selected by the
Department of Environment and Conservation (DEC) based on a variety of priorities
related to restoration and offset objectives (Table 1). These sites are now contained
within nature reserves; however they have had a rich history of disturbance since
European settlement. The study sites at these locations are areas of former agricultural
activity and have been cleared for several decades. Whilst the land in these areas in
recent times was predominantly used for grazing of sheep and other livestock, in the
earlier years of European settlement vegetable crops were the main activity, especially
within the area around Forrestdale Lake, and these areas were held in private
ownership until being assimilated into the reserve (DEC 2005). Historically, cleared
areas at both sites have become highly degraded and are now dominated by weeds
(CCWA et al. 2010). Adjacent areas at both Anketell and Forrestdale have had recent
restoration projects, both by topsoil transfer and other means, with mixed success
(Brundrett, pers. com.).
Jandakot Airport
Perth
Anketell Rd
Forrestdale Lake
Figure 2 – Site locations relative to Perth, Western Australia. The cross
indicating the location of Jandakot Airport from which soil was striped.
Triangles indicating the recipient sites of Forrestdale Lake (Nature
Reserve) and Anketell Rd. Adapted from the Nokia map service (Nokia
2012).
N
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Table 1 – Criteria used by DEC and their relative importance in recipient site selection. Adapted from
Brundrett (2012).
Criteria Importance
Carnaby’s Cockatoo feeding habitat high
Bush Forever Site high
Within 45 km of Jandakot Airport on Swan Coastal Plain high
Site with secure tenure high
Carnaby’s cockatoo breeding site proximity high
Carnaby’s cockatoo night roost proximity high
Site containing Caladenia huegelii high
Banksia woodland similar to Jandakot Airport (i.e. Bassendean sands) Very high
Proximity to Jandakot Airport Very high
Total area of remnant vegetation high
Declared rare or priority flora: WA State listings medium
Threatened ecological Community or Priority Ecological Community: WA State
listings
medium
Rare or priority fauna: WA State listings medium
2.2 FIELD SAMPLING AND DATA COLLECTION
Field work was conducted in two phases, first the sampling of soils prior to
transfer and second, the sampling of soils at the two recipient sites following transfer of
topsoil. Sampling prior to transfer occurred during the period 24-29 February 2012 and
post-transfer at Anketell Rd and Forrestdale Lake on 23 May 2012. Following field
collection, soil samples were stored in dry paper bags until 1st June when glasshouse
work was initiated. Assessment of the soil seed bank was conducted through mass
germination. This method was chosen due to its practicality over sieve removal of seeds
from soil (which can miss small seeds), and that it excludes seeds that are not viable
(Gross 1990; Baskin and Baskin 1998).
Sampling at Jandakot Airport consisted of four 200 m transects situated
throughout the area designated for clearing and topsoil transfer. Transects were made
up of six 10x10 m plots spaced at ~10 m increments for a total of 24 plots. Extant
vegetation was sampled at all 24 plots, half by DEC in December 2011 and the remaining
half as part of this study. Vegetation data collected by DEC was percentage cover per
species in 10% increments, whereas the subsequent vegetation data collected used the
Braun-Blanquet (1932) cover abundance method, with ranks assigned as shown in
Table 2. The two data sets were rationalised to be comparable for assessment of extant
vegetation and the soil seed bank.
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Table 2 – Ranking system for the allocation of cover rankings consistent with Braun-Blanquet
(1932).
Ranking Percentage cover 0.1 <1% 1 1-5% 2 5-25% 3 25-50% 4 50-75% 5 75-100%
Vegetation clearing and soil transfer at Jandakot Airport commenced in late
February and transfer was completed by mid-May. Although a large area of Banksia
woodland was cleared, a smaller proportion, approximately 17 ha, had topsoil removed
and transferred (Figure 3) (Brundrett 2012; DEC 2012). Soil stripping from Jandakot
Airport was specified as 70 mm (limits: 50 mm to 100 mm). A converted loader was
used for this process, with wing-like bucket attachments (Figure 4) to prevent
harvesting of soil at greater depths. Topsoil was then transferred to recipient sites,
Anketell Rd (10-12 ha) and Forrestdale Lake (5-6 ha). Where applicable, existing weedy
soil present at recipient sites was removed using a grader, to a depth of 30 mm (limits:
20 mm to 50 mm). Transferred topsoil was then spread over the top at two depths, 50
mm (limits: 40 mm to 60 mm) and 100 mm (limits: 80 mm to 120 mm) (DEC 2012). Two
spreading depths were used to enable further research to be conducted on this project.
Figure 3 - Position of transects and plots at Jandakot Airport. The area which soil was stripped
from is enclosed by the solid black lines. Plots are represented by the dots; with series of dots
forming transects which are labelled accordingly.
N
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Soil seed bank dynamics of transferred topsoil: evaluating restoration potentials
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Transfer of soil from Jandakot Airport was received at Lake Forestdale (Figure
5) and at Anketell Rd (Figure 6). An equal number of plots were set up (n=24) to match
the Jandakot site. These were allocated proportionally amongst the recipient sites based
on the extent of the area, with seven plots at Anketell East, four at Anketell West, five at
Forrestdale SW, five at Forrestdale NW and three at Forrestdale SE. These were
randomly positioned within the deep areas of transferred topsoil (~10 cm deep), to
ensure depth of sampling did not penetrate into the underlying, former soil surface.
Figure 4 - Main: Image of the loader used to harvest topsoil from Jandakot Airport by Urban
Resources. Insert: Side view of the wing-like bucket modifications used to prevent over harvesting of
topsoil.
Figure 5 – Site and plot locations at Forrestdale Lake. Dots representing plots, clustered in the deep
areas of transferred soil at the three smaller sites within the greater area of Forrestdale Lake
(Nature Reserve).
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Wing-like modifications
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Figure 6 – Site and plot locations and Anketell Road. Dots representing plots, clustered in the deep
areas of transferred soil at the three smaller sites within the greater Anketell Rd site.
Soil samples were required to give inference to the area as a whole. Soil
sampling tubes made from PVC pipe, 15.5 cm in diameter, 10 cm length were used
(Figure 7). Five subsamples per 10x10 m plot were taken and composited (Figure 8) for
each of two depths: 0-5 cm and 5-10 cm. This method was chosen as it provides a
consistent volume sample from which further calculations of density can be made and is
similar to the methods employed in other studies of soil seed banks (Bekker et al. 1997;
Fisher et al. 2009).
N
Figure 7 - Diagram of the soil sampling tube (not to
scale) used for sampling topsoil in this study.
Figure 8 – Sampling arangement within each plot
(not to scale), the circles representing the
locations of soil samples which were composited.
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2.2.1 GLASSHOUSE PREPARATION
Following final field sampling, soil samples were prepared in trays and placed in
the glasshouse for germination trials to assess seed bank composition. Trials were
initiated on 31 May – 01 June, 2012. To maximise germination rates, soil samples were
treated with heat and smoke together, as treatments are known to enhance germination
(Dixon, Roche, and Pate 1995; Keith 1997; Roche, Koch, and Dixon 1997; Keeley and
Fotheringham 1998; Tieu et al. 2001), and another set of soil samples prepared as
controls. The initial step was to prepare germination trays (35.5 cm x 29.5 cm x 5 cm);
192 trays were required for 96 soil samples (48 from pre-transfer site and 48 from post-
transfer sites). Germination trays were cleaned to remove any soil, seeds and pathogens
possibly present from past use. Trays were lined with Chux® cloth and filled with 1500
ml of vermiculite mixed with 500 ml of clean white sand, and the topsoil placed on top of
the sand-vermiculite mix.
Samples varied widely in their bulk densities due to the presence of high levels
of organic matter in some (especially proteoid roots). To make samples consistent,
topsoil samples were poured into a bucket and mixed. The weight of the total sample
was then taken before a quantity of this sample was put into two aluminium trays (29
cm x 19 cm x 5 cm) and weighed to be ~2100 g, with the aim to keep the quantity of soil
treated constant. This was not always possible due to some samples containing a high
proportion of proteoid roots, as these made large volume/low weight samples. All trays
were numbered and labelled as completed, as well assigned a score between 0 and 4 for
the amount of proteoid roots present in the tray, 0 being not present, 4 being 75-100%.
By recording mass used and total sample mass, a correction factor could be applied to
data later. Once trays were filled, half were treated with heat and smoke. Heat treatment
consisted of boiling water poured to fill the tray and left to cool, before being spread
evenly in a germination tray. Control trays were treated with an equal amount of cool
water.
Once all trays were prepared and located in the glasshouse, smoke treatment
was applied to samples that had previously been heat treated. This was done with
aqueous smoke solution REGEN 2000 SMOKEMASTER, a commercially available product
that has been found to replicate the effects of natural smoke associated with bushfires
(Thomas and Davies 2002; Wills and Read 2002). The solution was diluted 10 to 1 as
recommended by the suppliers, and 400 ml lots of the diluted solution were applied by
watering can to each germination tray that required treatment.
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To ensure possible contamination events of plant propagules entering the
glasshouse were identified, five clean seed-free sand trays were prepared in the same
manner as the other germination trays, but contained sterile sand instead of topsoil.
This was designed to indicate if experimental contamination had occurred from seed
entering the glasshouse through the air conditioning system or other means.
The glasshouse was air-conditioned to prevent excessive temperatures from
occurring, with settings designed not to exceed 24°C (range: 7-24°C). Watering was
maintained by automatic table reticulation, using misters set to run for 10 mins every
second day. Nevertheless, watering rates were found to be variable depending on table
position (range: 15-91 ml). Trays were monitored to evaluate if extra watering was
necessary, and every four weeks trays were re-randomised within the glasshouse to
mitigate any possible effects on germination among trays.
2.2.2 GERMINATION TRACKING
To quantify germination timing and identify species, emergence was checked
weekly and germinants marked with a series of colour-coded toothpicks. Each
germinant was marked with a toothpick consisting of a colour code (up to 4 bands of
colour) to identify germinants of the same species. Over time this identification was
changed as necessary, since germinants that appeared to be the same in early stages of
growth sometimes developed into several distinct species (Figure 9). Due to the very
high density of emerging seedlings, from time to time advanced individuals needed to be
pulled out to prevent too much competition for space in the trays; numbers and
identifications of plants pulled were recorded. Representative plants for each
identification code were potted up and grown on for identification purposes.
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2.2.3 DATA ANALYSIS
Normal parametric statistics were used to analyse overall patterns of density,
richness, and diversity, native and invasive species, growth habit and certain functional
traits. Data were analysed using multi-way ANOVA for density, richness and diversity on
a per tray basis to assess the potential effect of depth and treatment, plant functional
traits and other grouping factors, among and between sites. Linear regression was also
conducted to gain a measure of estimate, as well as to determine R-squared values. The
statistical analysis program R’ 2.14.2, published by The R Foundation for Statistical
Computing was used for these analysis (R 2012).
Density, richness and diversity are used in this study to investigate how topsoil
transfer influences the soil seed bank, and for overall comparisons between the various
treatments. Density was calculated (Equation 1) to provide a comparable measure of
germination across trays, while species richness, the average number of species in a
given sample, quantified biodiversity, and was important for ecological comparisons
(Gotelli and Colwell 2001). The Shannon-Wiener index of diversity (SWI) was used as
the measure of diversity (Equation 2). This index incorporates both richness and
evenness of the population (Sax 2002). All data was assessed on the groupings of site
(natural/transfer), depth (0-5 cm, 5-10 cm) and treatment (control, treated). All means
were graphed with 95% confidence intervals, to aid the interpretation of figures
(Cumming 2005, 2009). Unknown species were removed from graphical displays as they
represented less than 2% of the data on all occasions, most being less than 1%.
Figure 9 – Diagram of seeding marking procedure, bands indicating
colour code progression as identification became more developed.
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Sorensen’s similarity index (Equation 3) was used to determine the percentage
of species in common between the soil seed bank and the standing vegetation (Sorensen
1948). Some species had to be removed from this analysis due to being unidentified, to
prevent skewed results. Analysis was conducted with annual and serotinous species,
and with these species removed, for each treatment.
Multivariate community analysis methods were used to explore compositional
changes in the data. Ordination analysis of community composition was done using PC-
ORD version 6.08 (McCune and Mefford 2011). Nonmetric Multidimensional Scaling
(NMS) was used based on the Sorensen distance measure, which performs well in
demonstrating ecological gradients with complex data sets (Culman et al. 2008; Peck
2010). Stress values should ideally be under 20 for this type of ordination, however
values from 20 to 35 can still yield useful interpretations, as stress tends to increase
with sample size (McCune and Grace 2002).
Multi-response permutation procedures (MRPP) were used to assess the
evidence for differences between groups at the community level, evaluating differences
between two or more groups based on within-group similarities (McCune and Grace
2002; Peck 2010). MMRP has the advantages over other multivariate analysis
techniques in that it does not require distribution assumptions, which are rarely met in
ecological situations (Biondini, Bonham, and Redente 1985; Zimmerman, Goetz, and
Mielke 1985; McCune and Grace 2002). The Euclidean (Pythagorean) distance measure
was used for the MRPP due to its better representation of outliers in such an analysis
(McCune and Grace 2002). Rare species were removed from the ordination dataset if
only present once, resulting in 25 species being removed. Outlier analysis was then
( )
∑
Equation 1 – density
Equation 2 – Shannon-wiener index of diversity
Equation 3 – Sorensen’s index of similarity
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conducted; tray 96 was removed from the dataset on this basis. A random starting
configuration was used, and a thorough NMS was conducted with 250 runs. NMS
ordination was also run with native perennials only, however a useful ordination was
not found using PC-ORD.
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Soil seed bank dynamics of transferred topsoil: evaluating restoration potentials
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CHAPTER 3 – RESULTS
The results from this study from sampling conducted prior to topsoil removal
and post-transfer, subsequently examined in the glasshouse are presented and
statistically analysed in three main themes: seed bank dynamics, similarity, and
community analysis.
3.1 SEED BANK DYNAMICS
Seed bank dynamics were examined during germination trials lasting 13 weeks.
Emergence of seedlings peaking around week 8, with a total of 11,551 germinants
recorded over the entire period, belonging to 127 species (Figure 10).
Figure 10 – Proportion of total germinants the study over time (weeks).
Mean density of germinants found in this study was 1935 germinants m-2 this
ranged between 1692-4239 germinants m-2 in natural soils and 795-1016 germinants m-
2 in transferred soils. In total 79% of all germination occurred in the natural soils (0-5
cm: 73%, 5-10 cm: 27%). Transfer (post-transfer) soils on average contributed to 21%
of overall germination (0-5 cm: 54%, 5-10 cm: 46%) (Figure 11).
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Soil seed bank dynamics of transferred topsoil: evaluating restoration potentials
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There is a significant depth effect between 0-5 cm and 5-10 cm (F1, 185 = 47.3, p
<0.001), with an average difference of 2347.9 ± 348.7 germinants m-2. However this
depth effect is not the same between sites, indicated by the significant interaction
between depth and site (F1, 185 = 33.4, p <0.001). The overlap of confidence intervals in
transferred soil suggests that there is no depth effect in these soils. These transfer sites
had significantly lower densities than the natural sites (F1, 185 = 104.7, p <0.001), with an
average difference of 2472 ± 348.70 germinants m-2. Treatment had a significant
influence (F1, 185 = 8.5, p =0.003), increasing germination by an average 1537.8 ± 348
germinants m-2, but again this was only apparent in the natural soils, with a significant
interaction between site and treatment (F1, 185 =13.9, p <0.001), the transfer soils
showing no significant influence of treatment.
A total of 127 species were recorded in the study, with species richness patterns
found to be similar to those of density (Figure 12). A significant depth effect is present
(F1, 185 = 80.9, p <0.001), with on average 7.13 ± 0.90 more species being located in the 0-
5cm region. The depth response is different between the natural and transfer soils, as
indicated by the significant interaction between depth and site (F1, 185 = 26.2, p <0.001).
A significant difference between sites is also apparent (F1, 185 = 80.9, p <0.001) between
natural and transferred soils. Transferred soils contained an average of 7.04 ± 0.90 less
Figure 11 – Mean germinants m-2 by treatment across depth and site.
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species than the natural soils. Treatment has a significant influence on richness (F1, 185 =
7.4, p =0.007). Treatment effect between sites is not the same, with a strong interaction
influence (F1, 185 = 13.2, p <0.001), no significant response of treatment in the transfer
soils.
Figure 12 – Mean species richness by treatment across depth and site.
The mean Shannon-Wiener diversity (SWI) was 2.01, with natural 0-5 cm being
highest at 2.34. A somewhat different pattern to the density and richness plots can be
observed (Figure 13). There is a significant depth effect among both sites (F1, 185 = 34.8, p
<0.001), and a significant difference between sites (F1, 185 = 28.8, p <0.001). There are no
significant interactions of treatments.
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Figure 13 – Diversity using the Shannon-Wiener index, by treatment across depth and site.
Overall, grassy species (including grasses and grass-like species) contributed
812.58 germinants m-2 or 41.98%. Herbs accounted for 676.84 germinants m-2 or
34.97%, both the grassy and herbaceous species represented the majority of germinants
found within the seed bank (76.95%) (Figure 14). The remainder was filled by the
shrubs (166.53 germinants m-2, 8.60%), succulents (274.85 germinants m-2, 14.2%).
Grassy species were significantly influenced by depth (F1, 185 = 20.6, p <0.001),
representing a reduction between 0-5 cm and 5-10 cm of an average of 699.57 ± 166.58.
A significant site effect is also supported (F1, 185 = 106.2, p <0.001) and although
treatment is not significant for grassy species overall, there is a significant interaction
here, suggesting a shift in the pattern generated by treatment between sites (F1, 185 =
14.9, p <0.001).
The density of herbaceous species follows a similar trend to that of the grassy
species, having a depth effect (F1, 185 = 45.1, p <0.001), a site effect (F1, 185 = 73.0, p
<0.001), and significant treatment effect (F1, 185 = 3.9, p =0.05). Significant interactions
are seen between depth and site (F1, 185 = 38.1, p <0.001), also between site and
treatment (F1, 185 =4.4, p =0.04).
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The density attributed to shrub species, significant depth (F1, 185 =7.2, p =0.008),
site (F1, 185 =129.8, p <0.001), treatment (F1, 185 =20.3, p <0.001), interaction between
depth and treatment (F1, 185 = 5.0, p = 0.03) and interaction between site and treatment
(F1, 185 =8.4, p =0.004).
Succulent species has significant depth effect (F1, 185 = 5.6, p = 0.02) this differing
between sites (F1, 185 = 10.1, p = 0.002), significant site effect (F1, 185 = 5.2, p = 0.02), with
an increased representation in the transferred soils.
Figure 14 – Mean germinants m-2 by treatment, across depth and site, comparing growth forms.
Across all treatments and depths, invasive species represent on average 8%,
native annuals 68% and native perennials 17% (Figure 15).
Significant depth effect can be seen for invasive species is observed (F1, 185 = 26.8,
p <0.001), with an estimated reduction of 421.64 ± 59.75 germinants m-2. There is a
significant difference between sites (F1, 185 = 23.6, p <0.001), 412.70 ± 59.75. Treatment
has a negative effect on invasive species (F1, 185 = 5.6, p = 0.02), a difference of 187.02
germinants m-2. A significant interaction is present between depth and site (F1, 185 = 30.9,
p <0.001), indicating the depth effect was not the same among.
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Native annual species have a significant depth factor (F1, 185 = 33.9, p <0.001),
1592.80 ± 283.2 germinants m-2, significant site effect, (F1, 185 = 62.9, p <0.001), resulting
in a difference of 1506.50 ± 283.20 germinants m-2, and significant effect of treatment
(F1, 185 = 6.4, p = 0.01) resulting in an increase of 1149.40 ± 283.20. Significant
interactions can also be seen between depth and site (F1, 185 = 23.5, p <0.001), and
between site and treatment (F1, 185 = 12.7, p <0.001).
Native perennial species, have a significant depth effect (F1, 185 = 14.5, p <0.001),
184.34 ± 59.98 germinants m-2. Significant site effect is also present (F1, 185 = 175.2, p
<0.001) a difference of 417.61 ±59.98 germinant m-2. Treatment effect is significant (F1,
185 = 14.6, p <0.001), resulting in an increase of 304.52 germinants m-2. Significant
interactions of depth and site (F1, 185 = 7.0, p = 0.009) and site and treatment (F1, 185 =14.7,
p <0.001).
Figure 15 – Mean germinants m-2 of invasive species and native species split into longevity
categories, across treatment and depth (unknown species removed).
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The top 5 species contributed 47% to 65% of the overall germination in each
grouping (Table 3). All of the species represented in the high dominance categories are
native species. Native annuals are most dominant in the soil seed bank, with Crassula
colorata, Isolepis marginata and Centrolepis glabra occurring in the top 5 abundant
species across all groupings. Crassula colorata became most dominant in the transferred
soils.
Table 3 - Top 5 species by abundance for each treatment on natural and transferred soils. Blanks
indicate that the species was not in the top 5 most abundant for that treatment.
Germinants (Percentage of grouping) Species Natural
(control) Natural
(treated) Transfer (control)
Transfer (treated)
Centrolepis alepyroides - - 57 (4%) -
Centrolepis glabra 249 (7%) 566 (10%) 116 (9%) 67 (6%) Crassula colorata 244 (7%) 329 (6%) 466 (36%) 336 (31%) Gnephosis angianthoides - - 64 (5%) -
Isolepis marginata 617 (17%) 1257 (23%) 145 (11%) 136 (13%) Isotoma hypocrateriformis - - - 40 (4%)
Leucopogon conostephioides 262 (7%) - - - Poranthera microphylla - 346 (6%) - -
Trachymene pilosa 341 (9%) - - - Unknown_24 - 345 (6%) - 55 (5%)
Totals 1713 (47%) 2843 (51%) 848 (65%) 634 (59%)
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Native perennial (discussed previously), is made up of woody and non-woody species
(Figure 16). They differ in that woody species are effected by treatment (F1,185 = 20.1, p
<0.001), increasing density by 201.09 ± 36.24 germinants m-2, where as this is not
significant in non-woody species. Woody species also have a significant interaction of
depth and treatment (F1,185 = 4.9, p = 0.03). Non-woody have a significant interaction of
depth and site (F1,185 = 5.7, p = 0.02), where woody species do not.
Figure 16 – Density of native perennial species and their proportion of woody and non-woody.
Overall seeders contributed to 87% of the composition, a further 11% were
resprouting species. Seeder and resprouter species, despite being different in
abundance, both followed a similar trend to each other, both having significant depth
(F1, 185 = 44.6, p < 0.001; F1, 185 =9.5, p = 0.002), site (F1, 185 =87.2, p <0.001; F1, 185 =89.1, p
<0.001), and treatment (F1, 185 = 8.1, p 0.005; F1, 185 =7.0, p = 0.009) effect. Interactions
are seen between depth and site (F1, 185 = 32.2, p <0.001; F1, 185 = 4.1, p = 0.04), as well as
site and treatment (F1, 185 = 12.3, p <0.001; F1, 185 = 15.5, p <0.001), indicating the depth
and treatment effects are not the same between sites.
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Figure 17 – Density of germinants m-2 of seeders and resprouters across treatments, depths and
sites.
Overall the highest densities of germinants are associated with the mid-range of
proteoid root score >0 to 75%, the highest category of root matter (75% to 100%)
resulted in reduced germination.
Figure 18 – Mean density germinants m-2 of categories of Proteoid roots (0=0, 1=0-25%, 2=25-50%,
3=50-75%, 4=75-100%).
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3.2 SIMILARITY
Similarity between the soil seed bank and the extant vegetation, without
excluding species such as annuals and serotinous species, is 19% ± 2.8. With serotinous
species excluded from the standing vegetation and annuals removed from the soil seed
bank results from control (not treated soil seed bank), similarity then reduced to 15% ±
2.5. Treated soil seed banks result in the highest similarity of 19% ± 3.3.
Table 4 – Average number of species found in the soil seed bank (SSB) and above ground vegetation
(AGV), and the average similarity between the SSB and AGV, using Sorenson’s similarity index.
Average ± 95CI SSB AGV Sorenson’s similarity (%)
SSB and AGV (full)† 27 ± 2.2 33 ± 1.8 19 ± 2.8 SSB and AGV (control)* 5 ± 0.7 26 ± 1.4 15 ± 2.5 SSB and AGV (treated)* 9 ± 0.9 26 ± 1.4 19 ± 3.3
† Only unidentified species were removed.
* All serotinous species and annuals were removed from the standing vegetation. All annuals and unidentified species
were removed from the soil seed bank data. These would not have been consistently present between sampling.
3.3 COMMUNITY ANALYSIS
The NMS ordination of species abundance in all trays, using the Sorenson
distance measure, yielded a 2-dimentional solution with a final stress of 20.52, and
instability of 0.000 over 58 iterations (Figure 19). Axis 1 (capturing 44% of the
variability) is associated with a site based gradient, axis 2 (capturing 27% of the
variability) a depth gradient (cumulative r2 = 0.71). MRPP analysis was conducted on
several combinations of groups; distinct variations in community structure could be
seen between depth and site (A=0.14, p<0.001) and between natural and transferred
soils (A=0.10, p<0.001), however treatment showed no significant difference (A=0.01,
p<0.002).
The panel of joint plot comparisons, and associated correlation tables (Figure 20,
A, B and C) visually show the relationship of variables with the ordination axes. Only
vectors with an r2 > 0.20 are displayed. All growth forms are associated with depth
(Figure 20, A). Succulents are correlated with site, however they are the only growth
form negatively correlated with axis 1. All growth forms are correlated negatively with
axis 2, suggesting 0-5 cm natural soils are more important.
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Diversity, richness and proteoid score (Figure 20, B) show density and richness
correlated strongly with site, the negative correlation with axis 2 suggesting these
factors are also correlated with 0-5 cm natural soils. Proteoid score has a strong
correlation with natural sites as a whole.
Species, (Figure 20, C) show the most highly correlated species. Crassula colorata is the
only species negatively correlated with axis 1 (site), having a greater correlation with
depth. All other species here are correlated with the natural site.
Figure 19 – Ordination of all trays using NMS. Axis 1 correlated with site, from transfer to natural.
Axis 2 correlated with depth, 5-10cm to 0-5cm.
Page 36
Axis 1 (r) Axis 2 (r) Grassy .727 -.353 Herb .528 -.404 Shrub .654 -.043 Succulent -.096 -.649 Woody . .654 -.043 Native .648 -.474 Invasive .335 -.438 Annual .566 -.544 Perennial .727 -.038
Axis 1 (r) Axis 2 (r) Proteoid score
.625 .021
Richness .673 -.334 Density .624 -.503
Axis 1(r) Axis 2(r) Austrostipa compressa (austcomp)
.451 -.133
Centrolepis glabra (centglab)
.485 -.102
Crassula colorata (crascolo)
-.100 -.641
Isolepis marginata (isolmarg)
.577 -.292
Laxmannia sessiliflora (laxmSP)
.464 -.039
Leucopogon conostephioides (leuccono)
.452 .017
Figure 20 – Panel of three joint plot analyses, with correlations. A – Growth form and invasive status, B – Richness and diversity, C – species. Only those vectors with r2 values > 0.20
are displayed.
A. Joint plot analysis of growth form and invasive status. B. Joint plot analysis of richness and diversity. C. Joint plot analysis of species.
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CHAPTER 4 - DISCUSSION
4.1 INFLUENCE OF DEPTH OF TOPSOIL ON RESTORATION OUTCOMES
4.1.1 THE SOIL SEED GRADIENT
Consistent with previous work (Bellairs and Bell 1993; Read et al. 2000; Rokich
et al. 2000; Brown, Enright, and Miller 2003; Pickup, McDougall, and Whelan 2003;
Fenner and Thompson 2005; Merritt and Rokich 2006; Fisher et al. 2009), natural soils
had a strong depth gradient with most (73%) seeds in the top 5 cm. In transferred soils
there was no evidence of this depth gradient, although few studies have looked at this
aspect. Koch et al. (1996) found evidence of a mixed profile after the topsoil transfer
process had been conducted, finding only 15% of the seed within the top 5 cm (diluted
from 20 cm) of transferred soil, compared the results of this study which found 54%
(diluted from 7 cm, range: 5-10 cm) of the seed in this depth zone after transfer. A study
into soil seed banks affected by intense disturbance by Luzuriaga et al. (2005)
demonstrated a similar effect from the disturbance of ploughing.
It would be expected that transferred soils, after a mixing effect during the
transfer process, would be an average between the 0-5 cm and 5-10 cm depths of the
undisturbed soils. However, transferred soils produced less germinants than even the
undisturbed 5-10 cm from Jandakot Airport. Alcoa found in its mining operations within
the Jarrah forest of Western Australia that compaction had caused a 5% reduction in the
profile by up to 75 cm in depth (Croton and Watson 1987). Compaction occurring during
the clearing and to a lesser extent during the soil stripping process may have resulted in
a greater proportion of topsoil being removed from the soil source site (Figure 21). Thus
this would have a dilution effect reducing germination in the transferred samples.
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Figure 21 – Graphical representation of the potential influence of compaction in the soil stripping
process. Effect of over harvesting is for illustrative purposes only.
Although this study anticipated that the physical abrasion of transfer could be
beneficial by being a physical germination trigger, this was not the case, as germination
was less in transferred soils. The transfer process and compaction may have caused
damage to seeds within the soil seed bank, contributing to reduced germination
(Chambers and MacMahon 1994; Koch et al. 1996). Compaction is generally considered
a hindrance to in situ emergence of seedlings (Thill, Schirman, and Appleby 1979;
Kozlowski 1999; Botta et al. 2006), but no previous work has examined compaction
specifically for physical seed damage. In one of the few studies of the transfer process,
Koch et al. (1996) observed decreases in the germinable seed throughout the process,
with 31% of the original density found after respread of soil. Physical abrasion from
topsoil handling may destroy seed, especially smaller seeded species (Koch et al. 1996).
This trend is mirrored in this study, as it was observed that transferred soils were 26%
of the density of the pre-transfer soils.
4.1.2 LOSS OF ORGANIC MATTER (PROTEOID ROOTS)
The results show evidence that a dilution effect also occurs with the proteoid
organic matter within the soil. Proteoid roots are an adaption of the flora of south
Western Australia to low nutrient environments (Watt and Evans 1999; Neumann and
Martinoia 2002). Due to the rapid turnover of active roots, they add much organic
material to an otherwise impoverished soil structure, and therefore increase the
nutrient and water holding capacity of the soil (Neumann and Martinoia 2002). In this
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Soil seed bank dynamics of transferred topsoil: evaluating restoration potentials
33
study, the highest proteoid root scores are correlated with natural soils, and were highly
visible on site at Jandakot Airport (Figure 22). Therefore, as organic matter was less
prevalent in the transferred soils, this may have had implications on the success of
certain species that are adapted to the conditions provided by proteoid roots. DeFalco et
al. (2009) found a consistent positive relationship between cover of litter and the viable
soil density, proposing that litter is an indicator of degradation in arid lands. This may
have played some role in the high densities observed with root scores of >0 to 75%.
Organic material located in the top few centimetres of soil results in seedlings that are
more likely to establish successfully (Canham and Marks 1985; Baskin and Baskin
1998). Homogenization of the soil profile due to transfer can therefore create a loss of
stratification, seed dilution and loss of organic material that helps provide soil structure
needed for successful establishment.
Figure 22 – Photo of proteoid roots on site at Jandakot Airport.
4.1.3 IMPLICATIONS FOR THE TRANSFER PROCESS
From these results it can be seen that the mixing process that occurs when
transferring topsoil results in around 50% of the germinants lying beyond a germinable
depth. To maximise potential for restoration, soil stripping ideally needs to be a
maximum of 5 cm to retain high density, richness and structure in the transferred soil.
In order to take advantage of the seed store, its attributes, and the weed suppression
qualities of transferred topsoil, double stripping is a possible alternative to the single
stripping process conducted. Alcoa currently practices this, removing a shallow top
layer separately from underlying material, and subsequently returning soil in the same
order in which it was removed in, thus providing concentration of seed, suppression of
weeds, and maximisation of structural and biological attributes (Koch 2007a).
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4.2 THE EFFECT OF TOPSOIL TRANSFER ON GERMINANT COMPOSITION
All growth forms were reduced in abundance in the transfer process. Community
analysis shows that there is a significant difference between natural and transferred
soils. The highest densities, richness, and most plant functional types were correlated
with 0-5 cm in natural soils. A greater proportion of succulents can be seen in
transferred soils. The abundance of these is still equal or less than those of natural soils,
therefore the seeds of the succulents, predominately Crassula, were likely less negatively
affected by the process of transfer. Interestingly shrubs and woody species are of a
greater proportion in 5-10 cm natural samples than the 0-5 cm natural samples, whilst
there is a reduced proportion of grassy and herbaceous species. Several factors could
lead to such a difference between natural and transferred soils. Koch et al. (1996)
flagged damage to seed during the process as being influential of low establishment.
Therefore, those species with more durable seeds could be less diminished than those
smaller seeded species. Timing of topsoil transfer has previously been found to effect
outcomes for restoration and germination (Ward, Koch, and Ainsworth 1996; Rokich et
al. 2000; Merritt and Rokich 2006). The time which topsoil transfer occurred (late
autumn) may have had some influence on the soil seed bank viability. Transfer that
occurs earlier in a year offers improved seedling recruitment, due to the greater time
available for establishment while appropriate conditions are present (Merritt and
Rokich 2006). Other studies have produced similar recommendations, such as Rokich et
al. (2000) who demonstrated autumn transfer produced better results than winter and
spring.
4.3 GERMINATION SIMULATION WITH COMMON GERMINATION CUES
This study has found that smoke and heat treatment (in combination) offered an
enhanced density and richness in natural soils and no impact on diversity. Previous
literature has found smoke and heat in combination to be important in enhancing
germination of the soil seed bank (Dixon, Roche, and Pate 1995; Enright et al. 1997;
Morris 2000; Read et al. 2000; Merritt et al. 2007). More recently there has been
increasing literature on smoke and heat in combination being the best method in which
to induce germination of seed in a broader range of species (Read et al. 2000; Thomas,
Morris, and Auld 2003; Merritt and Rokich 2006). Although abundance did increase,
composition seems to have not been significantly altered. Overall only native species
were affected positively by treatment, invasive species were found to decline. Not all
species respond to heat and/or smoke treatment (Thomas, Morris, and Auld 2003;
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Soil seed bank dynamics of transferred topsoil: evaluating restoration potentials
35
Clarke and French 2005). Studies have also previously shown that invasive species are
more vulnerable to heat and smoke exposure (Smith, Bell, and Loneragan 1999; Read et
al. 2000), and therefore may decline in abundance with such a treatment.
Heat and smoke treatment of transferred soil samples did not significantly alter
the soil seed bank composition, although woody species showed a response to
treatment in transferred soils. In this study, soil of the transfer sites were damp due to
recent rains, and this may have negated the effect of the treatment. However, being
damp alone is unlikely to be the cause as all treated samples were wet due to the
application of boiling water for heat treatments . Alternatively seasonality is more likely
to have played an influence. Several studies, such as that by Roche, Dixon and Pate
(1998) and De Lange and Boucher (1993), found that the season of smoke application
had an effect on germination response, summer having a greater response than late
autumn or winter. As a result of damp soil, the sampled transfer topsoil may have
already started germinating. However, due to the vulnerability of seed being damaged,
the movement of transfer/sampling could consequently reduce germination. Losses of
presence and abundance of species have been observed after ripping in autumn and
winter, compared with summer (Ward, Koch, and Ainsworth 1996). This is evidence
that disturbance after rains damages the viability or physically damages the early
emerging seed, and therefore effects the perceived results, although it is likely that this
would only affect the early responders (weeds and annuals) (Fisher et al. 2009).
4.4 SOIL SEED BANK AND ITS RELATIONSHIP TO THE STANDING VEGETATION
4.4.1 SEED BANK COMPOSITION
The soil seed bank is not representative of standing vegetation, even though
invasive species had a surprisingly little impact on the soil seed bank (accounting for
only 7% of overall germination). The species present in high abundance across all
treatments, namely Crassula colorata, Isolepis marginata, and Centrolepis glabra, were all
native annuals, with this group representing 68% of the soil seed bank composition.
Native perennials are an important group and are the focus of restoration efforts.
Without these species restoration is unlikely to be successful; however this group only
represented a fraction of the composition (17%).
There is also little similarity to the standing vegetation on a plot by plot basis.
This study found the seed bank – extant vegetation similarity ranged between 15% and
19% (excluding serotinous and annual species). This is less than the value that
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Soil seed bank dynamics of transferred topsoil: evaluating restoration potentials
36
Hopfensperger (2007) reported in a review of similarity, finding 31% similarity for
forest ecosystems over 31 separate studies. However, these forest ecosystems were
found to be the least similar, being most similar in grasslands (Hopfensperger 2007).
The results of Hopfensperger (2007) suggests the idea that grasslands invoke
high similarity due to grasses having a similar (prolific) seeding habit. This is further
supported by Odgers’ (1994) study in Eucalypt forests where grass species have a
similarity of 82-93%, and De Villiers (2001) who reported a similarity of 75% of annuals
in the South African Karoo. With a mixed community such as a woodland or forest
system, the prolific seeders, such as the grasses and herbs, will be disproportionate in
number compared to the other functional types, as they have a higher degree of
similarity within the soil seed bank. In Mediterranean fire prone environments,
similarity is likely to be lower; Enright et al. (2007) reported values of 26-43% in an
area with a high degree of serotiny. Furthermore, this region has a high abundance of
resprouter species which do not produce high quantities of seed. Although it is the
standing vegetation that drives the assemblage of the soil seed bank, due to
disproportionate seeding and dormancy mechanisms amongst species, the soil seed
bank alone is not capable of restoring many of the species required to achieve
restoration goals.
4.4.2 SYSTEM RE-ASSEMBLAGE
Results suggest that the system after topsoil transfer is in the early stages of re-
assemblage. Overall 77% of the soil seed bank studied was comprised of grassy and
herbaceous species, and although there is a high proportion of native species (91%),
68% of these are annual species. This is suggestive of early re-assemblage through
secondary succession. It is not well documented if the early composition after topsoil
transfer adjusts over time to become more similar to that of the original vegetation. A
natural part of recovery from disturbance is the rapid recovery from the pioneer
species, as these species are generally short-lived annual species such as grasses and
herbs (predominately seeders) (Enright and Cameron 1988; Hobbs and Atkins 1990).
The low numbers of woody species recruitment (8.6% shrubs, 0% trees) found in this
study was likely due to the soil seed bank not being the only source of recruitment (the
seed bank alone excludes resprouter and serotinous species). It is important to consider
that some species may not germinate in the early stages, or require specific conditions
to initiate germination that may have not been met (e.g. repeated drying and
wetting)(Lush, Kaye, and Groves 1984; Hobbs and Atkins 1990; Pickup, McDougall, and
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Soil seed bank dynamics of transferred topsoil: evaluating restoration potentials
37
Whelan 2003; Fenner and Thompson 2005). But, as governed by the concept of
complete initial floristics (Egler 1954), the climax community of woodland is unlikely to
be achieved with topsoil transfer alone.
4.4.3 IMPLICATIONS OF THE SIMILARITY OF THE SOIL SEED BANK TO THE
STANDING VEGETATION.
The soil seed bank is not representative of the standing vegetation, even with
removal of annual and serotinous species. This is likely due to many of this category
being resprouter species and therefore not producing much seed in relation to seeder
species (87% seeders, 11% resprouters). Similarity is higher with treatment of smoke
and heat in combination. Although disproportionate (seeders vs. resprouters), density of
woody species overall is reasonable (47-166 germinants m-2), and structural
regeneration of shrubs is possible over time through succession.
The study timeframe of thirteen weeks may not have been long enough to fully
establish the longer term composition of the soil seed bank. A longer timeframe to
observe the germination and compositional profile for Banksia woodland species after
topsoil transfer may be useful to examine the richness and compositional trends further.
Furthermore, factors such as repeated wetting and drying were not demonstrated in
this experiment, it has been recognised to aid seeding emergence in some species (Lush,
Kaye, and Groves 1984; Pickup, McDougall, and Whelan 2003; Fenner and Thompson
2005).
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CHAPTER 5 – CONCLUSIONS AND RECOMMENDATIONS
5.1 CONCLUSIONS
Topsoil transfer is a useful tool for restoring degraded lands, especially where
other restoration options are not practical due to weed infestations or degraded soil
physical or chemical properties. This practice also aids to restore portions of the
vegetation community usually neglected by other forms of restoration due to
germination difficulties or technical restraints with these species. Furthermore,
restoring these species and a soil seed bank will aid future disturbance resilience of the
regenerated landscape. However, in the Banksia woodland of the SCP, topsoil transfer
alone may not adequately re-establish the structure and species composition required
for full recovery as many resprouter and serotinous species are often not
representative. Further ecological interventions through planting or direct seeding are
required for this to become a functioning Banksia woodland system.
The results of this project are highly useful for the optimization of the topsoil
transfer process. There is a dilution effect associated with the process of topsoil transfer,
which resulted in a loss of germinant density, richness and changes in the composition
of the soil seed bank. Timing is important in how effective treatment will be; treating
before rainfall while soil is still dry, being the key to successful results across all native
species groups. Treatment with germination cues (heat and smoke in combination)
resulted in an increase in density and species richness, overall improving the similarity
to the standing vegetation, but not influencing the relative proportions of growth forms.
Although there were some limitations to this study, mainly its length, these
results have several implications for topsoil transfer. The main findings suggest that the
transfer process needs rethinking due to the dramatic decrease in the germinable seed
bank post-transfer. The following section provides recommendations for future studies
and management of topsoil transfer.
5.2 RECOMMENDATIONS FOR MANAGEMENT OF TOPSOIL TRANSFER ON THE SWAN
COASTAL PLAIN
From this study, it is suggested that the soil seed bank does not highly resemble
the standing vegetation. Therefore, topsoil transfer should be conducted alongside other
means of restoration, such as planting or direct seeding, to make the post-restoration
community more resemblant of the original remnant bushland. There is supportive
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Soil seed bank dynamics of transferred topsoil: evaluating restoration potentials
39
evidence to suggest that topsoil transfer should be conducted in the summer months
while seeds are at their maximum dormancy. Once it becomes cooler and wetter, there
is a greater possibility of loss of seeds due to damage in the transfer process. Ideally,
treatment with smoke and heat should be conducted; a possible method could be the
application and subsequent burning of woody debris applied to the transfer areas,
therefore increasing the potential of serotinous species in restoration by releasing them
from the canopy.
Concentration of seed density is important to maximise the potential for
restoration using topsoil transfer. Stripping at a shallower depth will help increase seed
density by minimising the dilution effect seen with greater depth, enabling adjustment
for a potential compaction effect Alternatively, a form of double stripping could be
conducted to help retain other benefits associated with the soil, such as suppression of
weeds from underlying degraded soils, beneficial soil associations and chemical
properties that are also being transferred.
5.3 RECOMMENDATIONS FOR FUTURE RESEARCH
This research has raised questions of the topsoil transfer process, as well as
suggested ways that this process could be more successful. Continued monitoring of
past and present transfer projects is important for developing a full picture of topsoil
transfer and how these re-assembling communities change over time. Several areas can
be researched further to gain greater knowledge of the processes and the interactions
present to further develop solutions.
Soil stripping may have been inaccurate due to compaction; further research is
required on the influence of compaction and how much of an influence this plays. This
needs to be quantified in terms of measurable depth of compaction, so procedures can
be altered accordingly. Additionally the influence of compaction and other soil
disturbances involved need to be studied in regards to seed mortality in these
environments.
A small-scale simulated topsoil transfer (under controlled conditions) may be of
benefit to gain a detailed understanding of topsoil transfer, providing valuable insights
into the process by minimising potential variables. The simulation of topsoil transfer
could be achieved by gathering set-depth samples from remnant bushland and mixing
them together to simulate transfer, taking subsequent samples from this mixed soil, thus
removing potential contamination and compaction effects.
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REFERENCES
Ackzell, L. 1993. "A comparison of planting, sowing and natural regeneration for
Pinus sylvestris (L.) in boreal Sweden." Forest Ecology and Management no.
61 (3-4):229-245.
Baskin, C. C., and J. M. Baskin. 1998. Seeds : ecology, biogeography, and evolution
of dormancy and germination. San Diego, Calif.: Academic Press.
Bates, B. C., P. Hope, B. Ryan, I. Smith, and S. Charles. 2008. "Key findings from the
indian ocean climate initiative and their impact on policy development in
Australia." Climate Change no. 89 (3):339-354.
Bekker, R. M., G. L. Verweij, R. E. N. Smith, R. Reine, J. P. Bakker, and S.
Schneider. 1997. "Soil seed banks in European Grasslands: Does land use
affect regeneration perspectives?" Journal of Applied Ecology no. 34
(5):1293-1310.
Bell, D. T. 1999. "The Process of Germination in Australian Species." Australian
Journal of Botany no. 47 (4):475 - 517.
Bell, D. T., J. A. Plummer, and S. K. Taylor. 1993. "Seed Germination Ecology in
Southwestern Western Australia." The Botanical Review no. 59 (1):24-73.
Bellairs, S. M., and D. T. Bell. 1993. "Seed stores for restoration of species-rich
shrubland vegetation following mining in Western Australia." Restoration
Ecology no. 1 (4):1061-2971.
Biondini, M. E., C. D. Bonham, and E. F. Redente. 1985. "Secondary succesional
patterns ina Sagebrush (Artemisia tridentata) community as they relate to
disturbance and soil biological activity." Vegetatio no. 60 (1):25-36.
Blank, Robert R., and James A. Young. 1998. "Heated substrate and smoke: Influence
on seed emergence and plant growth." Journal of Range Management no. 51
(5).
Bolland, M. 1998. Soils of the Swan Coastal Plain. Bunbury: Dept. of Agriculture,
Western Australia.
BOM, (Bureau of Meterology). 2012. Climate of Perth Airport. Australian
Government 2012 [cited 1st October 2012]. Available from
http://www.bom.gov.au/wa/perth_airport/climate.shtml.
Botta, G. F., D. Jorajuria, H. Rosatto, and C. Ferrero. 2006. "Light tractor traffic
frequency on soil compaction in the Rolling Pampa region of Argentina." Soil
& Tillage Research no. 86 (1):9-14.
Braun-Blanquet, J. 1932. Plant Sociology: The study of plant communities. Translated
by G.D. Fuller and H.S. Conard. Edited by G.D. Fuller and H.S Conard. New
York: McGraw-Hill.
Page 47
Soil seed bank dynamics of transferred topsoil: evaluating restoration potentials
41
Brown, J, N. J. Enright, and B. P. Miller. 2003. "Seed production and germination in
two rare and three common co-occurring Acacia species from south-east
Australia." Austral Ecology no. 28 (3):271-280.
Brundrett, M. C. 2012. Jandakot Airport Banksia Woodland Offets Project. Paper read
at Banksia Woodland habitat restoration: Jandakot Airport offset information
session, 15 May 2012, at Banjup Community Hall.
Canham, C. D., and P. L. Marks. 1985. "The response of woody plants to disturbance:
patterns of establishment and growth." In The Ecology of natural disturbance
and patch dynamics, edited by S. T. A. Pickett and P. S. White. London:
Academic Press.
CBD, (Convention on Biological Diversity). 2012. COP 10 decision X/2: Strategic
plan for biodiversity 2011-2020 2010 [cited 19th October 2012].
CCWA, (Conservation Commission of Western Australia), Department of
Environment and Conservation, City of Cockburn, City of Armadale, and
Town of Kwinana. 2010. Jandakot Regional Park: Management Plan 2010.
Perth.
Chambers, J. C., and J. A. MacMahon. 1994. "A day in the life of a seed: Movements
and fates of seeds and their implications for natural and managed systems."
Annual review of ecology and systematics no. 25 (1):263-292.
Clarke, S., and K. French. 2005. "Germination response to heat and smoke of 22
Poaceae species from grassy woodlands." Australian Journal of Botany no. 53
(5):445-454.
Clewell, A. F., and J. Aronson. 2007. Ecological restoration : principles, values, and
structure of an emerging profession. Washington: Island Press.
Croton, J. T., and G. D. Watson. 1987. Mining related compaction: A case study on
the darling range, Western Australia. ALCOA of Australia Limited.
Culman, S. W., H. G. Gauch, C. B. Blackwood, and J. E. Thies. 2008. "Analysis of T-
RFLP data using analysis of varience and ordnation methods: A comparative
study." Journal of Microbiological Methods no. 75 (1):55-63.
Cumming, G. 2005. "Inference by eye: confidence intervals and how to read pictures
of data." The American psycologist no. 60 (2):170-180.
———. 2009. "Inference by eye: reading the overlap of indipendent confidence
intervals." Statistics in medicine no. 28 (2):205-220.
Dainou, K., A. Bauduin, N. Bourland, J. Gillet, F. Feteke, and J. Doucet. 2011. "Soil
seed bank characteristics in Cameroonian rainforests and implications for
post-logging forest recovery." Ecological Engineering no. 37 (10):1499-1576.
De lange, J. H., and C. Boucher. 1990. "Autecological studies on Audonia capitata
(Bruniaceae). 1. Plant-derived smoke as a seed germination cue." South
African Journal of Botany no. 56:188-202.
Page 48
Soil seed bank dynamics of transferred topsoil: evaluating restoration potentials
42
———. 1993. "Autecological studies on a Audouinii capitata (Bruniaceae) .4. seed
production, seed banks and seedling recruitment." South African Journal of
Botany no. 59 (2):145-155.
De Villiers, A. J., M. W. Van Rooyen, and G. K. Theron. 2001. "Seedbank
phytosociology of the strand veld succulent Karoo, South Africa: A pre-
mining benchmark survey for rehabilitation." Land Degradation &
Development no. 12 (2):119-130.
DEC, (Department of Environment and Conservation). 2005. Forrestdale Lake Nature
Reserve: Management Plan 2005. Perth: Deparment of Environment and
Conservation.
———. 2012. Topsoil stripping, transport and re-spreading for rehabilitation. Perth:
Department of Environment and Conservation.
DeFalco, L. A., T. C. Esque, J. M. Kane, and M. B. Nicklas. 2009. "Seed banks in a
degraded desert shrubland: Influence of soil surface condition and harvester
ant activity on seed abundance." Journal of Arid Environments no. 73
(10):885-893.
Dixon, K. W., S. Roche, and J. S. Pate. 1995. "The Promotive Effect of Smoke
Derived from Burnt Native Vegetation on Seed Germination." Oecologia no.
101 (2):185-192.
Egler, F. E. 1954. "Vegetation science concepts I. Initial floristic composition, a
factor in old-field vegetation development." vegetatio no. 4 (6):412-417.
Engel, V. L., and J. A. Parrotta. 2001. "An evaluation of direct seeding for
reforestation of degraded lands in central Sao Paulo state, Brazil." Forest
Ecology and Management no. 152 (1):169-181.
Enright, N. J., and E. K. Cameron. 1988. "The soil seed bank of a kauri (Agathis
australis) forest remnant near Aukland, New Zealand." New Zealand Journal
of Botany no. 26 (2):223-236.
Enright, N. J., D. Goldblum, P. Ata, and D. H. Ashton. 1997. "The independent
effects of heat, smoke and ash on emergence of seedlings from the soil seed
bank of healthy Eucalyptus woodland in Grampians (Gariwerd) National Park,
western Victoria." Australian Journal of Ecology no. 22 (1):81-88.
Enright, N. J., and A. Kintrup. 2001. "Effects of smoke, heat and charred wood on the
germination of dormant soil-stored seeds from Eucalyptus baxteri heathy-
woodland in Victoria, SE Australia." Austral Ecology no. 26 (2):132-141.
Enright, N. J., E. Mosner, B. P. Miller, N. Johnson, and B. B. Lamont. 2007. "Soil Vs.
canopy seed storage and plant species coexistence in species-rich Australian
shrublands." Ecology no. 88 (9):2292-2304.
Fenner, M., and K. Thompson. 2005. The ecology of seeds. Cambridge: Cambridge
University Press.
Page 49
Soil seed bank dynamics of transferred topsoil: evaluating restoration potentials
43
Fisher, J. L., W. A. Loneragan, K. W. Dixon, and E. J. Veneklaas. 2009. "Soil seed
bank compositional change constrains biodiversity in an invaded species-rich
woodland." Biological Conservation no. 142 (2):256-269.
Folke, C., S. Carpenter, B. Walker, M. Scheffer, T. Elmqvist, L. Gunderson, and C. S.
Holling. 2004. "Regime shifts, resilience, and biodiversity in ecosystem
management." Annual Review of Ecology, Evolution, and Systematics no. 35
(1):557-581.
Fry, A. D. 2011. Restoration Techniques in Banksia Woodlands. Honours, School of
Environmental Science, Murdoch University, Perth.
Gallant, A. J. E., K. J. Hennessy, and J. Risbey. 2007. "Trends in rainfall indices for
six Austraian regions: 1910-2005." Australian Meteorological Magazine no.
56 (4):223-239.
Gardner, J. H., and D. T. Bell. 2007. "Bauxite mining restoration by Alcoa World
Alumina Auatralia in Western Australia: Social, Political, Historical, and
Environmental Contexts." Restoration Ecology no. 15 (4):S3-S10.
Gotelli, N. J., and R. K. Colwell. 2001. "Quantifying biodiversity: procedures and
pitfalls in the measurement and comparison of species richness." Ecology
letters no. 4 (4):379-391.
Grimm, N. B., S. H. Faeth, N. E. Golubiewski, C. L. Redman, J. Wu, X. Dai, and J.
M. Briggs. 2008. "Global Change and the Ecology of Cities." Science no. 319
(5864):756 - 760.
Gross, K. 1990. "A comparison of methods for estimation seed numbers in soil."
Journal of Ecology no. 78 (4):1079.
Harper, J. L. 1977. Population Biology of Plants. London: Academic Press.
Hobbs, R. J. 2007. "Setting effective and realistic restoration goals: key directions for
research." Restoration Ecology no. 15 (2):354-357.
Hobbs, R. J., and L. Atkins. 1990. "Fire-related dynamics of a banksia woodland in
south-western Western Australia." Austrailan Journal of Botany no. 38 (1):97-
110.
Hobbs, R. J., L. M. Hallett, P. R. Ehrlich, and H. A. Mooney. 2011. "Intervention
Ecology: Applying Ecological Science in the Twenty-first Centuary."
BioScience no. 61 (6):442-450.
Holmes, P. M., and R. M. Cowling. 1997. "Diversity, composition and guild structure
relationships between soil-stored seed banks and mature vegetation in alian
plant-invaded south african fynbos shrublands." Plant Ecology no. 133
(1):107-122.
Hopfensperger, K. N. 2007. "A review of similarity between seedbank and standing
vegetation across ecosystems." Oikos no. 116 (9):1438-1448.
Page 50
Soil seed bank dynamics of transferred topsoil: evaluating restoration potentials
44
Howard, G. S., and M. J. Samuel. 1979. "The Value of fresh-stripped topsoil as a
source of useful plants for surface mine revegetation." Journal of Range
Management no. 32 (1):76-77.
Hughes, L. 2003. "Climate change in Australia: Trends, projections and impacts."
Austral Ecology no. 28 (4):423-443.
JAH, (Jandakot Airport Holdings). 2009. Jandakot Airport Environmental Strategy
2009. Jandakot: Jandakot Airport Holdings.
Jasper, D. A. 2007. "Beneficial soil microorganisms of the Jarrah Forest and their
recovery in Bauxite mine restoration in Southwestern Australia." Restoration
Ecology no. 15 (4):S74 - S84.
Keeley, J. E., and C. J. Fotheringham. 1998. "Smoke-Induced Seed Germination in
California Chaparral." Ecology no. 79 (7):2320-2336.
Keeley, J. E., and S. C. Keeley. 1987. "Role of fire in the germination of chaparral
herbs and suffrutescents." Madrono no. 34 (3):240-249.
Keith, D. A. 1997. "Combined effects of heat shock, smoke and darkness on
germination of Epacris stuartii Stapf., an endangered fire-prone Australian
shrub." Oecologia no. 112 (3):340-344.
———. 2012. "Funtional traits: their roles in understanding and predicting biotic
responses to fire regimes from individuals to landscapes." In Flammable
Australia: Fire Regimes, Biodiversity and Ecosystems in a Changing World,
edited by Ross A Bradstock, A. Malcolm Gill and Richard J. Williams.
Collingwood: CSIRO Publishing.
Knight, A. J. P., P. E. Beale, and G. S. Dalton. 1998. "Direct seeding of native trees
and shrubs in low rainfall areas and non-wetting sands in South Australia."
Agroforestry Systems no. 39 (3):225-239.
Koch, J. M. 2007a. "Alcoa's Mining and Restoration Process in South western
Australia." Restoration Ecology no. 15 (4):S11-S16.
———. 2007b. "Restoring a Jarrah forest understory vegetation after Bauxite mining
in Western Australia." Restoration Ecology no. 15 (4):S26-S39.
Koch, J. M., A. M. Ruschmann, and T. K. Morald. 2009. "Effect of time since burn on
soil seedbanks in the jarrah forest of Western Australia." Australian Journal of
Botany no. 57 (8):647-660.
Koch, J. M., S. C. Ward, C. D. Grant, and G. L. Ainsworth. 1996. "Effects of Bauxite
mine restoration operations on topsoil seed reserves in the Jarrah forest of
Western Australia." Restoration Ecology no. 4 (4):368-376.
Kozlowski, T. T. 1999. "Soil compaction and growth of woody plants." Scandinavian
Journal of Forest Research no. 14 (6):596-619.
Page 51
Soil seed bank dynamics of transferred topsoil: evaluating restoration potentials
45
Lamont, B. B., D. C. Le Maitre, R. M. Cowling, and N. J. Enright. 1991. "Canopy
seed storage in woody plants." The Botanical Review no. 57 (4):277-317.
Lindon, H. L., and E. Menges. 2008. "Scientific Note: Effects of Smoke on seed
Germination of Twenty Species of Fire-Prone abitats in Florida." Castanea no.
73 (2):106-110.
Loreau, M., S. Naeem, P. Inchausti, J. Bengtsson, J. P. Grime, A. Hector, D. U.
Hooper, M. A. Huston, D. Raffaelli, B. Schmid, D. Tilman, and D. A. Wardle.
2001. "Biodiversity and ecosystem functioning: Current knowledge and future
challenges." Science no. 294 (5543):804-808.
Lush, W. M., P. E. Kaye, and R. H. Groves. 1984. "Germination of Clematis
microphylla seeds following weathering and other treatments." Australian
Journal of Botany no. 32 (2):121-129.
Luzuriaga, A. L., A. Escudero, J. M. Olano, and J. Loidi. 2005. "Regenerative role of
seed banks following an intense soil disturbance." Acta Oecologica no. 27
(1):57-66.
Martins, A. M., and V. L. Engel. 2007. "Soil seed banks in tropical forest fragments
with different disturbance histories in southeastern Brazil." Ecological
Engineering no. 31 (3):165-174.
McArthur, W. M. 1991. Reference soils of south-western Australia. Perth: Dept. of
Agriculture, Western Australia.
McCarthy, D. P., P. F. Donald, J. P. W. Scharlemann, G. M. Buchanan, A. Balmford,
J. M. H. Green, L. A. Bennun, N. D. Burgess, L. D.C. Fishpool, S. T. Garnett,
D. L. Leonard, R. F. Maloney, P. Morling, H. M. Schaefer, A. Symes, D. A.
Wiedenfeld, and S. H. M. Butchart. 2012. "Financial Costs of Meeting Global
Biodiversity Conservation Targets: Current Spending and Unmet Needs."
Science no. 338 (6109):946-949.
McCune, B., and J. B. Grace. 2002. Analysis of ecological communities. Oregon:
MjM Software Design.
PC-ORD 6.08. MjM Software, Oregon.
Merritt, D. J., and D. Rokich. 2006. "Seed biology and ecology." In Australian Seeds:
A Guide to their Collection, Identification and Biology, edited by L.
Sweedman and D. J. Merritt. Collingwood: CSIRO Publishing.
Merritt, D. J., S. R. Turner, S. Clarke, and K. W. Dixon. 2007. "Seed dormancy and
germination stimulation syndromes for Australian species." Australian
Journal of Botany no. 55 (3):336-344.
Morris, E. C. 2000. "Germination response of seven east Australian Grevillea species
(Proteaceae) to smoke, heat exposure and scarification." Austrailan Journal of
Botany no. 48 (2):179-189.
Page 52
Soil seed bank dynamics of transferred topsoil: evaluating restoration potentials
46
Myers, N., R. A. Mittermeier, C. G. Mittermeier, G. A. B. da Fonseca, and J. Kent.
2000. "Biodiversity hotspots for conservation priorities." Nature no. 403
(6772):853-858.
Neumann, G., and E. Martinoia. 2002. "Cluster roots: and underground adaptation for
survival in extream environments." Trends in Plant Science no. 7 (4):1360-
1385.
Nokia. 2012. Nokia Maps: City and Country Maps - Driving Directions - Satellite
Views - Routes. Nokia 2012 [cited 11th October 2012]. Available from
http://maps.nokia.com/.
Odgers, B. M. 1994. "Seed banks and vegetation of three contrastion sites in an urban
eucalypt forest reserve." Australian Journal of Botany no. 42 (4):371-382.
Paczkowska, G, and A. R. Chapman. 2000. The Western Australian Flora: A
descriptive catalogue. Nedlands: Wildflower Society of Western Australia.
Palmer, M. A., and S. Filoso. 2009. "Restoration of ecosystem services for
environmental markets." Science no. 325 (5940):575-576.
Peck, J. E. 2010. Multivariate analysis for community ecologists: Step-by-step using
PC-ORD. Oregon: MjM Software Design.
Pickup, M., K. L. McDougall, and R. J. Whelan. 2003. "Fire and flood: Soil-stored
seed bank and germination ecology in the endangered Carrrington Falls
Grevillea (Grevillea rivularis, Proteacea)." Austral Ecology no. 28 (2):128-
136.
Pierce, S. M., K. Esler, and R. M. Cowling. 1995. "Smoke-induced germination of
succulents (Mesembryanthemaceae) from fire-prone and fire-free habitats in
South Africa." Oecologia no. 102 (4):520-522.
Powell, R. 2009. Leaf and branch: Trees and tall shrubs of Perth. Kensington:
Department of Environment and Conservation.
R: A Language and Environment for Statistical Computing 2.14.2. R Foundation for
Ststistical Computing, Vienna.
Ralph, M. 2006. Seed collection of Australian Native Plants: for revegetation, tree
planting and direct seeding. South Lyonville: Bushland Horticulture.
Ramalho, C. E., and R. J. Hobbs. 2012. "Time for a change: dynamic urban ecology."
Trends in Ecology and Evolution no. 27 (3):179-188.
Read, T. R., S. M. Bellairs, D. R. Mulligan, and D. Lamb. 2000. "Smoke and heat
effects on soil seed bank germination for the re-establishment of native forest
community in New South Wales." Austral Ecology no. 25 (1):48-57.
Roche, S., K. W. Dixon, and J. S. Pate. 1998. "For everything a season: Smoke-
induced seed germination and seedling recruitment in a Western Australian
Banksia woodland." Australian Journal of Ecology no. 23 (2):111-120.
Page 53
Soil seed bank dynamics of transferred topsoil: evaluating restoration potentials
47
Roche, S., J. M. Koch, and K. W. Dixon. 1997. "Smoke enhanced seed germination
for mine rehabilitation in the southwest of Western Australia." Restoration
Ecology no. 5 (3):191-203.
Rokich, D. P., and K. W. Dixon. 2007. "Recent advances in restoration ecology, with
a focus on the Banksia woodland and the smoke germination tool." Australian
Journal of Botany no. 55 (3):375-389.
Rokich, D. P., K. W. Dixon, K. Sivasithamparam, and K. A. Meney. 2000. "Topsoil
handling and storage effects on woodland restoration in Western Australia."
Restoration Ecology no. 8 (2):196-208.
Sax, D. F. 2002. "Equal diversity in disparate species assemblages: a comparison of
native and exotic woodlands in California." Global Ecology & Biogeography
no. 11 (1):49-57.
SER, (Society for Ecological Restoration International Science & Policy Working
Group). 2004. "The SER International Primer on Ecological Restoration." In.
Tucson: Society for Ecological Restoration International.
SEWPC, (Department of Sustainability Environment Water Population and
Communities). 2012. Australian National Resourses Atlas 2009 [cited 20th
September 2012]. Available from
http://www.anra.gov.au/topics/vegetation/assessment/wa/ibra-swa-threatened-
ecosystems.html.
Skrindo, A. B., and P. A. Pedersen. 2004. "Natural revegetation of indigenous
roadside vegetation by propagules from topsoil." Urban Forestry & Urban
Greening no. 3 (1):29-37.
Smith, M. A., D. T. Bell, and W. A. Loneragan. 1999. "Comparative seed germination
ecology of Austrostipa compressa and Ehrharta calycina (Poaceae) in
Western Australian Banksia woodland." Australian Journal of Ecology no. 24
(1):35-42.
Sorensen, T. A. 1948. "A method of establishing groups of equal amplitude in plant
sociology based on similarity of species content, and its application to analysis
of the vegetation on Danish commons." Biologiske Skrifter no. 5:1-34.
Sweedman, L., and G. Brand. 2006. "Seed collection in the field." In Australian
seeds: A guide to their collection, identification and biology, edited by L.
Sweedman and D. J. Merritt. Collingwood: CSIRO Publishing.
Tacey, W. H., D. P. Olsen, and G. H. M Watson. 1977. Rehabilitation of mine wastes
in a temperate environment. In Environmental Research Bulletin Number 2:
ALCOA.
Thill, D. C., R. D. Schirman, and A. P. Appleby. 1979. "Influence of soil moisture,
temperature, and compaction on germination and emergence of Downy Brome
(Bromus tectorum)." Weed Science no. 27 (6):625-630.
Page 54
Soil seed bank dynamics of transferred topsoil: evaluating restoration potentials
48
Thomas, P. B., E. C. Morris, and T. D. Auld. 2003. "Interactive effects of heat shock
and smoke on germination of nine species forming soil seed banks within the
Sydney region." Austral Ecology no. 28 (6):674-683.
Thomas, T. H., and I. Davies. 2002. "Responses of dormant heather (Calluna
vulgaris) seeds to light, tempwerature, chemical and advancement treatments."
Plant Growth Regulation no. 37 (1):23-29.
Tieu, A., K. W. Dixon, K. A. Meney, and K. Sivasithamparam. 2001. "The interaction
of heat and smoke in the release of seed dormancy in seven species from
southwestern Western Australia." Annals of Botany no. 88 (2):259-265.
Timbal, B., J. M. Arblaster, and S. Power. 2006. "Attribution of the late-twentieth-
century rainfall decline in Southwest Australia." Journal of Climate no. 19
(10):2046-2060.
Tozer, M., C. C. Simpson, B. D. E. Mackenzie, and M. Blanche. 2012. "Topsoil
translocation: an effective method for increasing plant species diversity in
restored sites." Australasian Plant Conservation no. 20 (3):2.
Valbuena, L., and L. Trabaud. 2001. "Contribution of the soil seed bank to post-fire
recovery of a heathland." Plant Ecology no. 152 (2):175-183.
Valentine, L., B. Wilson, W. Stock, T. Fleming, G. Hardy, and R. Hobbs. 2011.
Bulletin No.19 - Managing habitat for endangered species: Carnaby's black-
cockatoo, food resources and time since last fire. In Research Findings 2011.
Perth: Centre of Excellence for Climate Change, Woodland & Forest Health.
Viani, R. A. G., and R. R. Rodrigues. 2009. "Potential of the seedling community of a
forest fragment for tropical forest restoration." Scientia Agricola no. 66
(6):772-779.
Vlahos, S., and D. T. Bell. 1986. "Soil seed-bank components of the northern jarrah
forest of Western Australia." Australian Journal of Ecology no. 11 (2):17 -
179.
Ward, S. C., J. M. Koch, and G. L. Ainsworth. 1996. "The effect of timing of
rehabilitation procedures on the establishment of a Jarrah forest after Bauxite
mining." Restoration Ecology no. 4 (1):19-24.
Watt, M., and J. R. Evans. 1999. "Proteoid Roots. Physiology and Development."
Plant Physiology no. 121 (2):317-323.
Wills, T. J., and J. Read. 2002. "Effects of heat and smoke on germination of soil-
stored seed in a south-eastern Australian sand heathland." Australian Journal
of Botany no. 50 (2):197-206.
Wills, T.J., and J Read. 2007. "Soil Seed Bank Dynamics in Post-Fire Heathland
Succession in South-Eastern Australia." Plant Ecology no. 190 (1):1-12.
Page 55
Soil seed bank dynamics of transferred topsoil: evaluating restoration potentials
49
Zimmerman, G. M., H. Goetz, and P. W. Mielke. 1985. "Use of an improved
ststistical method for group comparisons to study effects of prairie fire."
Ecology no. 66 (2):606-611.
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APPENDICES
APPENDIX A – STATISTICAL SUMMARIES OF ALL NORMAL PARAMETRIC ANALYSIS
Table A1 – Statistical summaries of all normal parametric analysis. “NS” denotes non-significant values.
Density Richness Diversity Invasive Density
Native Density
Grassy Species
Herb Species
Shrub Species
Succulent Species
Native Annual
Native Perennial
Woody Non-woody Seeder Resprouter
Depth P-Value <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 0.008 0.02 <0.001 <0.001 0.009 0.002 <0.001 0.002
F-Value 47.3 80.9 34.8 26.8 43.6 20.6 45.1 7.1 5.6 33.9 14.5 7.0 10.3 44.6 9.5
Estimate (SE)
-2347.90 (348.70)
-7.13 (0.90) -0.42 (0.09) -421.64 (59.75)
-1933.70 (315.30)
-699.57 (166.58)
-1331.5 (195.1)
-43.83 (36.24)
-280.14 (98.62)
-1592.8 (283.2)
-184.34 (59.98)
-44.26 (36.24)
-140.08 (41.20)
-2091.20 (321.40)
-147.39 (48.38)
Site P-Value <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 0.02 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001
F-Value 104.7 144.8 28.8 23.6 109.4 106.2 73.0 129.8 5.2 62.9 175.2 130.3 85.2 87.2 89.1
Estimate (SE)
-2472.00 (348.70)
-7.04 (0.90) -0.35 (0.09) -412.70 (59.75)
-2076.60 (315.30)
-874.88 (166.58)
-1421.6 (195.1)
-212.40 (36.24)
33.09 (98.62)
-1506.5 (283.2)
-417.61 (59.98)
-212.82 36.24
-204.79 (41.20)
-2135.30 (321.40)
-210.37 (48.38)
Treatment P-Value 0.003 0.007
NS
0.02 <0.001 0.008 <0.001 <0.001
NS
0.01 <0.001 <0.001
NS
0.005 0.009
F-Value 8.5 7.4 5.6 13.6 7.1 3.9 20.3 6.4 14.6 20.1 8.1 7.0
Estimate (SE)
1537.80 (348.70)
3.54 (0.90) -187.02 (59.75)
1720.00 (315.30)
619.25 (166.58)
578.0 (195.1)
201.52 (36.24)
1149.4 (283.2)
304.52 (59.98)
201.09 (36.24)
1379.30 (321.40)
179.38 (48.38)
Depth:site P-Value <0.001 <0.001
NS
<0.001 <0.001 0.009 <0.001
NS
0.002 <0.001 0.009
NS
0.02 <0.001 0.04
F-Value 33.4 26.2 30.9 28.8 7.0 38.1 10.1 23.5 7.0 5.7 32.2 4.1
Estimate (SE)
2326.40 (402.60)
5.33 (1.04) 383.30 (68.99)
1953.20 (364.10)
509.33 (192.35)
1390.0 (225.2)
361.53 (113.87)
1585.9 (327.0)
183.78 (69.26)
113.75 (47.57)
2106.0 371.20
113.32 55.86
Depth:Treatment P-Value
NS NS NS NS NS NS NS
0.03
NS NS NS
0.03
NS NS NS F-Value 5.0 4.9
Estimate (SE)
-93.43 (41.85)
-92.59 (41.85)
Site:Treatment P-Value <0.001 <0.001
NS NS
<0.001 <0.001 0.04 0.004
NS
<0.001 <0.001 0.004 0.003 <0.001 <0.001
F-Value 13.9 13.2 19.5 14.9 4.4 8.4 12.7 14.7 8.5 9.1 12.3 15.5
Estimate (SE)
-1502.50 (402.60)
-3.79 (1.04) -1608.70 (364.10)
-742.11 (192.35)
-471.3 (225.2)
-121.13 (41.85)
-1165.6 (327.0)
-265.26 (69.26)
-121.97 (41.85)
-143.29 (47.57)
-1301.80 (371.20)
-219.82 (55.86)
Adjusted R-Squared 0.51 0.58 0.25 0.31 0.52 0.44 0.45 0.47 0.08 0.41 0.54 0.47 0.36 0.48 0.38
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APPENDIX B – SPECIES LISTS
Table B1 - List of species recorded in plant surveys conducted at Jandakot Airport, with invasive
status.
Genus species Status
Acacia pulchella native
Acacia saligna native
Acacia willdenowiana native
Adenanthos cygnorum native
Allocasuarina humilis native
Amphipogon turbinatus native
Arnocrinum preissii native
Austrostipa compressa native
Banksia attenuata native
Banksia ilicifolia native
Banksia menziesii native
Baumea vaginata native
Beaufortia elegans native
Bossiaea eriocarpa native
Briza maxima invasive
Burchardia congesta native
Caladenia flava native
Caladenia sp. native
Calectasia narragara native
Calytrix flavescens native
Calytrix fraseri native
Carpobrotus edulis invasive
Cassytha sp. native
Chamaescilla corymbosa native
Chordifex sinuosus native
Conostephium pendulum native
Conostephium preissii native
Conostylis aculeata native
Conostylis juncea native
Conostylis setigera native
Croninia kingiana native
Dampiera linearis native
Dasypogon bromeliifolius native
Daviesia triflora native
Desmocladus fasciculatus native
Desmocladus flexuosus native
Ehrharta calycina invasive
Eremaea asterocarpa native
Eremaea pauciflora native
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Eucalyptus marginata native
Eucalyptus todtiana native
Gastrolobium capitatum native
Gladiolus caryophyllaceus invasive
Gompholobium tomentosum native
Haemodorum spicatum native
Hardenbergia comptoniana native
Hemiandra pungens native
Hensmania turbinata native
Hibbertia huegelii native
Hibbertia hypericoides native
Hibbertia subvaginata native
Hypocalymma robustum native
Hypochaeris glabra invasive
Hypolaena exsulca native
Jacksonia furcellata native
Lasiopetalum drummondii native
Laxmannia squarrosa native
Lechenaultia floribunda native
Lepidosperma drummondii native
Lepidosperma squamatum native
Lepidosperma tenue native
Leucopogon conostephioides native
Leucopogon insularis native
Leucopogon sp. native
Levenhookia stipitata native
Lomandra caespitosa native
Lomandra hermaphrodita native
Lomandra micrantha native
Lomandra preissii native
Lomandra sp. native
Lomandra suaveolens native
Lyginia barbata native
Lysimachia arvensis invasive
Melaleuca ryeae native
Melaleuca systena native
Melaleuca thymoides native
Nuytsia floribunda native
Patersonia occidentalis native
Persoonia saccata native
Petrophile linearis native
Philotheca spicata native
Phlebocarya ciliata native
Phlebocarya filifolia native
Pimelea sulphurea native
Podolepis gracilis native
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Rhytidosperma occidentale native
Scaevola repens native
Schoenus curvifolius native
Schoenus efoliatus native
Scholtzia involucrata native
Solanum nigrum invasive
Sonchus oleraceus invasive
Stirlingia latifolia native
Stylidium piliferum native
Stylidium repens native
Stylidium sp. native
Tetraria octandra native
Thysanotus thyrsoideus native
Thysanotus triandrus native
Trachymene pilosa native
Ursinia anthemoides invasive
Wahlenbergia preissii native
Xanthorrhoea preissii native
Xanthosia candida native
Table B2 – List of species germinated in glasshouse experiment, with invasive status, and number of
germinants observed across treatments.
Natural Transfer
Genus species Status control treated control treated
Acacia pulchella native 0 4 0 1
Aira caryophyllea invasive 31 11 6 1
Aira cupaniana invasive 1 1 3 0
Anigozanthos humilis native 5 26 2 5
Anigozanthos manglesii native 0 20 0 0
Arctotheca calendula invasive 1 0 5 11
Austrostipa compressa native 126 91 7 3
Bossiaea eriocarpa native 3 8 1 3
Briza maxima invasive 89 33 2 1
Briza minor invasive 1 0 0 0
Bromus diandrus invasive 2 1 14 20
Calandrinia granulifera native 3 0 5 1
Calandrinia corrigioloides native 13 31 0 2
Cardamine hirsuta invasive 0 0 2 0
Carpobrotus edulis invasive 1 7 10 16
Cassytha sp. native 0 2 0 0
Centrolepis alepyroides native 152 202 57 31
Centrolepis aristata native 0 0 5 2
Centrolepis glabra native 249 566 116 67
Chamaescilla corymbosa native 116 38 17 2
Conostephium pendulum native 0 2 0 0
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Conostylis aculeata native 0 40 0 1
Conostylis juncea native 4 20 0 0
Conostylis setigera native 0 3 0 0
Conyza bonariensis invasive 34 10 12 2
Crassula colorata native 244 329 466 336
Cynodon dactylon invasive 0 0 0 1
Dasypogon bromeliifolius native 1 1 0 0
Daviesia pedunculata native 1 0 0 0
Daviesia triflora native 0 1 0 0
Desmocladus flexuosus native 6 6 2 0
Drosera erythrorhiza native 0 1 0 0
Drosera menziesii native 0 3 0 0
Drosera platypoda native 2 1 1 0
Drosera platypoda native 3 5 1 0
Ehrharta calycina invasive 0 1 0 5
Euphorbia peplus invasive 1 0 0 1
Gamochaeta coarctata invasive 1 0 1 1
Gladiolus caryophyllaceus invasive 48 13 12 0
Gnaphalium indutum native 0 0 0 1
Gnephosis angianthoides native 2 0 64 26
Gompholobium tomentosum native 5 62 6 20
Hensmania turbinata native 1 0 0 0
Hibbertia hypericoides native 1 0 4 0
Hibbertia sp. native 0 1 0 0
Hibbertia sp. native 2 1 0 0
Hibbertia subvaginata native 8 7 3 1
Homalosciadium homalocarpum native 21 26 1 4
Hypocalymma angustifolium native 1 1 0 0
Hypochaeris glabra invasive 66 60 13 9
Isolepis marginata native 617 1257 145 136
Isotoma hypocrateriformis native 1 37 1 40
Jacksonia furcellata native 1 3 0 0
Juncus sp. unknown 1 8 13 17
Laxmannia ramosa native 1 5 1 0
Laxmannia sessiliflora native 164 152 57 29
Lechenaultia floribunda native 8 169 3 12
Lepidosperma drummondii native 1 0 0 0
Leucopogon conostephioides native 262 173 19 28
Leucopogon sp. native 14 4 1 3
Levenhookia pusilla native 15 3 0 3
Levenhookia stipitata native 68 85 6 4
Lolium sp. invasive 42 14 2 3
Lomandra caespitosa native 1 2 0 0
Lomandra hermaphrodita native 0 3 0 0
Lomandra preissii native 0 0 0 1
Lomandra sp. native 1 0 0 0
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Lotus sp. invasive 0 0 1 1
Lyginia barbata native 3 1 0 0
Lysimachia arvensis invasive 1 0 0 0
Medicago sp. invasive 0 0 1 0
Microtis sp. native 5 1 1 0
Patersonia occidentalis native 1 3 2 0
Phlebocarya ciliata native 2 2 0 0
Phlebocarya filifolia native 0 1 0 1
Podolepis lessonii native 23 74 0 0
Podotheca chrysantha native 0 0 1 0
Podotheca gnaphalioides native 9 14 6 4
Poranthera microphylla native 21 46 3 4
Poranthera microphylla native 75 346 35 21
Rhodanthe corymbosa native 60 47 2 1
Rhodanthe laevis native 6 3 0 0
Romulea rosea invasive 0 2 11 1
Sagina apetala invasive 0 0 1 0
Sagina apetala invasive 0 0 2 0
Schoenus curvifolius native 1 1 0 0
Solanum americanum invasive 1 0 0 0
Solanum nigrum invasive 3 2 3 1
Sonchus oleraceus invasive 1 1 5 0
Spergula arvensis invasive 0 0 1 0
Stylidium brunonianum native 3 141 1 4
Stylidium emarginatum native 132 204 15 26
Thysanotus manglesianus native 4 1 2 0
Thysanotus sp. native 3 2 0 1
Thysanotus triandrus native 1 1 1 0
Trachymene pilosa native 341 179 21 32
Trifolium campestre invasive 4 5 2 0
Unknown_01 invasive 8 5 1 1
Unknown_02 native 0 1 1 0
Unknown_03 native 1 4 1 4
Unknown_04 native 0 1 0 0
Unknown_05 native 127 93 2 0
Unknown_06 unknown 0 0 0 1
Unknown_07 native 4 4 0 0
Unknown_08 native 1 0 0 0
Unknown_09 native 0 0 1 0
Unknown_10 native 4 10 22 19
Unknown_11 native 1 14 1 5
Unknown_12 unknown 2 0 2 1
Unknown_13 unknown 1 2 0 0
Unknown_14 native 0 0 0 2
Unknown_15 native 0 0 1 0
Unknown_16 native 0 19 0 0
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Unknown_17 unknown 0 0 2 1
Unknown_18 native 2 3 1 1
Unknown_19 native 0 0 0 1
Unknown_20 native 7 73 1 10
Unknown_21 native 0 2 20 3
Unknown_22 native 1 3 0 0
Unknown_23 native 0 1 0 0
Unknown_24 native 4 345 5 55
Unknown_25 unknown 6 0 9 4
Ursinia anthemoides invasive 86 56 0 8
Vulpia sp. invasive 65 25 7 2
Wahlenbergia capensis invasive 13 32 9 2
Wahlenbergia preissii native 147 222 7 15
Xanthosia candida native 2 5 1 1
Totals 3624 5547 1297 1083