Terrestrial ecosystem threat status assessment 2018 - comparison with 2011 assessment for provincial agencies August 2019 Author: Andrew Skowno Contributors: Maphale Matlala, Jasper Slingsby, Donovan Kirkwood, Domitilla Raimondo, Lize von Staden, Stephen Holness, Mervyn Lotter, Genevieve Pence, Fahiema Daniels, Amanda Driver, Philip Desmet, Anisha Dayaram Cite as: Skowno AL, Matlala M, Slingsby J, Kirkwood D, Raimondo DC, von Staden L, Holness SD, Lotter M, Pence G, Daniels F, Driver A, Desmet PG, Dayaram A (2019). Terrestrial ecosystem threat status assessment 2018 - comparison with 2011 assessment for provincial agencies. National Biodiversity Assessment 2018 Technical Report. South African National Biodiversity Institute, Pretoria. KEY POINTS Ecosystem threat status is a head line indicator in the National Biodiversity Assessment. In the NBA 2011 the ecosystem threat status indicator for terrestrial ecosystems was linked to the National List of Threatened Terrestrial Ecosystems which appeared in the government gazette in 2011. Since 2011 there have been significant changes to both the national vegetation map (which includes a wide range of refinements) and the land cover data (which now includes land cover change between 1990 and 2014). In addition to the new input data there is a new international ecosystem threats assessment framework developed by the IUCN, known as the Red List of Ecosystems (RLE). Designed to complement the existing Red List of Species framework, the IUCN RLE is gaining traction and there are numerous high impact scientific publications focusing on its concepts and implementation. South Africa was an early adopter of the IUCN species red listing methodology and is now a global leader in threatened species work. For the NBA 2018 we have chosen to adopt IUCN RLE methodology. Although the IUCN RLE and the South African system are very similar in concept and application, there are subtle differences that, when combined with the differences in the input vegetation and land cover data, result in substantial differences between the 2018 list of threatened ecosystems and the 2011 list. In the report below we detail the preliminary results of a 2018 ecosystem threat status assessment using the IUCN RLE method. We first assessed all 458 terrestrial ecosystem types using national datasets (this is referred to as the referred as the “core” assessment) and then followed up with “supplementary” assessments for specific ecosystem types. Supplimentary assessments are the principal avenue for experts to contribute to the national ecosystem assessment process. If the threat status of an ecosystem is judged to be too low or too high, and there is evidence to support this, then a supplementary assessment can be undertaken - using criteria and thresholds contained in the IUCN RLE framework. In parallel to the ecosystem threat assessment, we also have the opportunity to identify a new category of ecosystems for national listing. These “ecosystems of special concern” do not trigger any specific threat status criteria in the IUCN of South African system, but are potentially of special conservation concern due to endemism, sensitivity to change, value as ecological infrastructure, ecosystem service delivery or exceptional cultural value. This has been successfully implemented by SANBIs threatened species unit; who have identified “range restricted rare species” as an additional category for national reporting (but which are excluded from IUCN listing processes). This category could also cater for the various special ecosystem listed previously in South Africa using Criteria F of the 2011 system. The process and plan for updating the national listing of threatened ecosystems / gazette has not yet been finalized. As a first step in this process we have produced a provincial level comparison on the NEMBA 2011 list of threatened ecosystems and the preliminary 2018 Red List of Ecosystems. This will lay the foundation for discussion on the update of regulations linked to the new list of threatened terrestrial ecosystems. Ideally the national list of ecosystems would be biennially updated by SANBI based on the latest assessments and information (as per species), rather than a static list that is gazette for 5-10 years as is currently the situation. SANBIs policy experts will have to investigate the possibility for this.
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Terrestrial ecosystem threat status assessment 2018 - comparison with 2011 assessment for provincial agencies
August 2019
Author: Andrew Skowno
Contributors: Maphale Matlala, Jasper Slingsby, Donovan Kirkwood, Domitilla Raimondo, Lize von Staden, Stephen
Cite as: Skowno AL, Matlala M, Slingsby J, Kirkwood D, Raimondo DC, von Staden L, Holness SD, Lotter M, Pence G, Daniels F, Driver A, Desmet PG, Dayaram A (2019). Terrestrial ecosystem threat status assessment 2018 - comparison with 2011 assessment for provincial agencies. National Biodiversity Assessment 2018 Technical Report. South African National Biodiversity Institute, Pretoria.
KEY POINTS Ecosystem threat status is a head line indicator in the National Biodiversity Assessment.
In the NBA 2011 the ecosystem threat status indicator for terrestrial ecosystems was linked to the National List of
Threatened Terrestrial Ecosystems which appeared in the government gazette in 2011.
Since 2011 there have been significant changes to both the national vegetation map (which includes a wide range
of refinements) and the land cover data (which now includes land cover change between 1990 and 2014).
In addition to the new input data there is a new international ecosystem threats assessment framework developed
by the IUCN, known as the Red List of Ecosystems (RLE). Designed to complement the existing Red List of Species
framework, the IUCN RLE is gaining traction and there are numerous high impact scientific publications focusing on
its concepts and implementation.
South Africa was an early adopter of the IUCN species red listing methodology and is now a global leader in
threatened species work. For the NBA 2018 we have chosen to adopt IUCN RLE methodology.
Although the IUCN RLE and the South African system are very similar in concept and application, there are subtle
differences that, when combined with the differences in the input vegetation and land cover data, result in
substantial differences between the 2018 list of threatened ecosystems and the 2011 list.
In the report below we detail the preliminary results of a 2018 ecosystem threat status assessment using the IUCN
RLE method. We first assessed all 458 terrestrial ecosystem types using national datasets (this is referred to as the
referred as the “core” assessment) and then followed up with “supplementary” assessments for specific ecosystem
types.
Supplimentary assessments are the principal avenue for experts to contribute to the national ecosystem
assessment process. If the threat status of an ecosystem is judged to be too low or too high, and there is evidence
to support this, then a supplementary assessment can be undertaken - using criteria and thresholds contained in
the IUCN RLE framework.
In parallel to the ecosystem threat assessment, we also have the opportunity to identify a new category of
ecosystems for national listing. These “ecosystems of special concern” do not trigger any specific threat status
criteria in the IUCN of South African system, but are potentially of special conservation concern due to endemism,
sensitivity to change, value as ecological infrastructure, ecosystem service delivery or exceptional cultural value.
This has been successfully implemented by SANBIs threatened species unit; who have identified “range restricted
rare species” as an additional category for national reporting (but which are excluded from IUCN listing processes).
This category could also cater for the various special ecosystem listed previously in South Africa using Criteria F of
the 2011 system.
The process and plan for updating the national listing of threatened ecosystems / gazette has not yet been finalized.
As a first step in this process we have produced a provincial level comparison on the NEMBA 2011 list of threatened
ecosystems and the preliminary 2018 Red List of Ecosystems. This will lay the foundation for discussion on the
update of regulations linked to the new list of threatened terrestrial ecosystems.
Ideally the national list of ecosystems would be biennially updated by SANBI based on the latest assessments and
information (as per species), rather than a static list that is gazette for 5-10 years as is currently the situation. SANBIs
policy experts will have to investigate the possibility for this.
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 3
ecosystem types with restricted distribution ranges. It is envisaged that the preliminary national RLE
resulting from this assessment will be considered as the baseline for the nation, and that it will be updated
as additional information becomes available – to be released biennially. If the threat status of an ecosystem
type is: a) considered an underestimate; or b) if the data used in the assessment is considered inaccurate or
inadequate; or c) if a researcher can develop new datasets to address additional criteria for selected
ecosystems; then further supplementary assessments should be undertaken. The core assessment will be
updated when updated national land cover change data becomes available.
Appendix 2 includes information on the similarities and differences in the IUCN RLE system applied in 2018
and the South African system applied in 2011.
RESULTS AND DISCUSSION
NBA RLE 2018 results
The first implementation of the IUCN RLE for South African terrestrial ecosystems (458 vegetation types) for
the NBA 2018 resulted in the listing of 35 Critically Endangered, 39 Endangered and 29 Vulnerable
ecosystems (Table 1). While 8% of ecosystem types are Critically Endangered, this amounts to less than 1%
of the extent of remaining natural habitat in South Africa. Endangered ecosystems make up 9% of
ecosystems by type and 3% by extent. Six percent of ecosystems types are Vulnerable, amounting to 4% of
the natural remaining habitat of South Africa (Table 8). The most influential criteria in the RLE assessment
were Criteria B1(i) (restricted distribution & continuing declines in geographic distribution) which
contributed to the listing of 74/103 ecosystem types and Criterion A3 (historical loss of habitat) which
contributed to the listing of 67/103 ecosystem types (Table 9). The supplementary assessment of Criterion
B1 using the threatened species pressures database contributed to the listing of 49/103 ecosystem types,
of which 13 were listed purely due to this criterion. Criterion D (biotic disruption – based on ecosystem
degradation) contributed to the listing of 5/103 ecosystem types.
Table 1. Summary of the assessment outcomes; including the number of ecosystem types per category & proportion of the natural areas remaining per category.
Category (IUCN RLE) Number of
ecosystems Extent of natural
Habitat (km2) Percentage of natural
habitat of SA
Critically Endangered 35 5 905 0.6%
Endangered 39 28 983 3%
Vulnerable 29 42 460 4%
Least Concern 355 882 821 77%
Total for South Africa 458 960 168 100%
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 4
Figure 1. IUCN RLE 2018 version 5: Historical extent of threatened ecosystem types
Figure 2. IUCN RLE 2018 version 5: Remaining natural extent of each threatened ecosystem type
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 5
Comparing the 2011 NEMBA and 2018 NBA RLE ecosystem threat status results
The 2018 assessment focused on vegetation types (458 units assessed) while the NEMA 2011 assessment
focused on 438 vegetation types and 108 additional “special ecosystems” (a total of 546 ecosystem types
assessed). The inclusion of special ecosystems, which were not conceptually consistent and ranged from
individual forest patches (i.e. on patch of a more widely distributed ecosystem type) to specific locations
which included range of different ecosystem types, represents a substantial difference between the
assessments. These special ecosystems, which were assessed using Criterion F of the South African
framework, do not fit the definition of an ecosystem type provided in the IUCN RLE framework, and are
better described as the outputs of biodiversity ecosystem prioritization processes. The 2018 and future
assessments of terrestrial ecosystems in South Africa will be applied to the ecosystem units described and
delineated in the national vegetation map (as recommended by the Terrestrial Reference Group in
November 2017). This data set is curated and updated regularly by SANBI, and the units described (i.e.
within Mucina and Rutherford 2006, and updates) are consistent with level 4/5 of the global ecosystem
typology that is under development (Keith et al., in prep).
While the exclusion of these special ecosystems in 2018 resulted in fewer threatened ecosystem types
being listed in 2018 when compared to 2011 (103 vs. 225), Critically Endangered and Endangered
ecosystem types cover a similar extent (when considering the natural remaining habitat). This is important
from a regulation point of view as the “footprint” of these two categories have the largest impact on
environmental regulation processes and procedures. Vulnerable ecosystem types covered a substantially
larger area in 2011 than in the 2018 assessment, but the impact of this on regulatory processes in limited.
Differences in the Western Cape are mostly driven by the use of a threatened species focused criteria in the
NEMBA 2011 assessment (SA Criteria D1) (Appendix 2). The 2018 NBA RLE assessment incorporates threats
such as invasive alien species and overgrazing as evidence of ongoing decline only in restricted range
ecosystems (linked to IUCN Criteria B1ii, B2ii).
There are ecosystem types which, based on the new land cover data, are in lower threat category than the
2011 NEMBA assessment. In some cases this represents an improved understanding of the extent of
natural habitat remaining, and in others it may be that the new land cover data is over estimating the
extent of natural habitat. We have implemented numerous adjustments to the land cover change data to
prevent this (i.e. mapping secondary natural areas) but these ecosystems should be investigated further
and supplementary assessments should be undertaken.
Table 2. Comparison of the results of the 2018 Red List of Ecosystems and the 2011 National List of Threatened Terrestrial Ecosystems. The table includes the number of ecosystem types per category and the proportion of the natural habitat of South Africa within each category. The 2011 assessment included 438 vegetation types and 108 “special ecosystem types” (ranging from forest sub-vegetation units to habitat for threatened animals); the 2018 assessment was applied to an updated vegetation map with 458 units.
Category (IUCN RLE)
2011 2018
Number of ecosystems
Percentage of natural habitat of SA
Number of ecosystems
Percentage of natural habitat of SA
Critically Endangered 53 <1% 35 <1%
Endangered 64 2% 39 3%
Vulnerable 108 7% 29 4%
Total number of ecosystem assessed
546
458
Some of the special ecosystems listed under SA Criteria F and A2 (forest patches) in the 2011 NEMBA
assessment are no longer listed as threatened, or have been placed in a lower threat category in the 2018
NEBA RLE. These ecosystems are now part of provincial CBA networks and are more appropriately highlighted
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 6
through biodiversity prioritization processes rather than threat status assessments. To complement the RLE
we aim to develop an additional list of “ecosystems of special concern”, much like the “species of special
concern” which picks up on endemic, localized or otherwise unique ecosystems in South Africa. The special
forest areas included in the 2011 NEMBA list using SA Criteria F and A2 are a good starting point for such as
list.
The western portion of the Eastern Cape has a number of differences which are driven by changes to the
national vegetation map (specifically adjustments to the Albany Thicket biome), and the inclusion
degradation data, developed by the STEP programme (Subtropical Thicket Ecosystem Programme, 2002-
2004).
Appendix 3 lists each terrestrial ecosystem type assessed in 2018 using the IUCN RLE and included in the
National Biodiversity Assessment, and compares the ecosystem threat status with the 2011 NEMBA listing.
Figure 3. (a) Threatened terrestrial ecosystems published in 2011 (the NEMBA list); (b) the 2018 NBA RLE. The maps are broadly similar with most differences concentrated in the Albany Thicket biome, Grassland biome and Fynbos biome.
Table 3. The 2018 NBA RLE - Provincial breakdown showing the percentage of the natural remaining habitat in each threat category. The number of ecosystems types is shown in parenthesis. Note the provincial stats do not sum to the SA totals since some ecosystem types occur in multiple provinces.
Province (RLE 2018) Critically Endangered Endangered Vulnerable Total Threatened Least Concern
Western Cape 4.1% (25) 5.6% (20) 0.8% (9) 10.5% 89.5%
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 7
Table 4. The 2011 National List of Threatened Terrestrial Ecosystem (NEMBA list) - Provincial breakdown showing the percentage of the natural remaining habitat in each threat category. The number of ecosystems is shown in parenthesis. Note the provincial stats do not sum to the SA totals since some ecosystem types occur in multiple provinces.
Province (NEMBA 2011) Critically Endangered Endangered Vulnerable Total Threatened Least Concern
Western Cape 4.9% (21) 1.7% (14) 11.5% (23) 18.09% 81.9% Table 5. Summary of changes in threatened ecosystem listing per province between 2011 NEMBA list and 2018 NBA RLE.
Province Narrative of Changes
Eastern Cape
Threatened ecosystems now cover 8% of the natural remaining habitat extent of the province, up from 4% estimated in 2011. The number of threatened ecosystem types has decreased slightly from 19 to 18. The vast majority of these threatened types are vulnerable. The major contributors to the differences are the use of a new map of Albany Thicket biome ecosystems types and the use of the degradation data from the STEP programme.
Free State
Threatened ecosystems now cover 12% of the natural remaining habitat extent of the province, down from 15% estimated in 2011. The number of threatened ecosystem types has decreased from 9 to 5. The differences are caused by the higher habitat loss thresholds for Endangered and Critically Endangered categories in the IUCN system compared to the South African system.
Gauteng
Threatened ecosystems now cover 45% of the natural remaining habitat extent of the province, down from 57% estimated in 2011. The number of threatened ecosystem types has also decreased from 24 to 7. These decreases are due to the exclusion of SA Criteria F “special” ecosystems which are now captured as priorities within systematic biodiversity plans (e.g. critical biodiversity areas).
KwaZulu-Natal
Threatened ecosystems now cover 30% of the natural remaining habitat extent of the province, up from 26% estimated in 2011. The number of threatened ecosystem types has decreased substantially from 102 to 18 due to the exclusion of a large number of small “special” ecosystems (identified under SA Criterion F) which are now captured as priorities within systematic biodiversity plans (e.g. critical biodiversity areas).
Limpopo
Threatened ecosystems now cover 5% of the natural remaining habitat extent of the province, down from 7% estimated in 2011. The number of threatened ecosystem types has decreased from 12 to 7. The differences are caused by the higher habitat loss thresholds for Endangered and Critically Endangered categories in the IUCN system compared to the South African system.
Mpumalanga
Threatened ecosystems now cover 30% of the natural remaining habitat extent of the province, down from 47% estimated in 2011. The number of threatened ecosystem types has decreased substantially from 39 to 9 due to the exclusion of a large number of small “special” ecosystems (identified under SA Criterion F) which are now captured as priorities within systematic biodiversity plans (e.g. critical biodiversity areas).
North West
Threatened ecosystems now cover 12% of the natural remaining habitat extent of the province, down from 25% estimated in 2011. The number of threatened ecosystem types has decreased from 14 to 7. The differences are caused by the higher habitat loss thresholds for Endangered and Critically Endangered categories in the IUCN system compared to the South African system and the exclusion of some small “special” ecosystems (identified under SA Criterion F) which are now captured as priorities within systematic biodiversity plans (e.g. critical biodiversity areas).
Northern Cape Less than 1% of the natural remaining ecosystem extent of the Province is listed as threatened in both 2018 and 2011 assessments. The number of listed ecosystem types remains the same.
Western Cape
Approximately 10% of the natural remaining ecosystem extent of the Province is listed as threatened in both 2018 and 2011 assessments. The number of ecosystem types listed as threatened has decreased slightly from 58 to 54 due to a refinement in the approach for including threatened species data.
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 8
Limitations
The key shortcoming of all of these ecosystem threat status assessments is that we lack appropriate data
on land degradation or biotic disruption of ecosystems. This means that in many regions the ecosystem
assessments will underestimate the risk of collapse. This is dealt with to some degree in the thicket biome;
but in other biomes it is a very challenging problem that will need significant focussed research. One
aspect of degradation that should be possible to map accurately and therefore use in ecosystem
assessment is distribution and abundance on alien invasive species. At least for grasses and woody plants
that reach high abundances and high visibility this certainly seems possible in the near future. Another
challenge is that for many of our ecosystems we do not have a clear model of ecosystem function against
which we can measure biotic disruption or degradation.
A further shortcoming of this assessment is that it relies on data collected in 2013/2014 – which makes it 4
years old. This is not ideal, and as automated and global scale remote sensing becomes more accessible it is
hoped that future assessments will not suffer from this long time delay. As soon as new land cover data
become available (scheduled for 2018 release by the Department of Environmental Affairs) SANBI has set
up a system to automatically update the lists (though there are many steps for which expert validation are
required); the aim is to reduce this time lag to less than one year.
REFERENCES
Bland, L. M., Keith, D. A., Miller, R. M., Rodríguez, J. P., & Murray, N. J. (2017). Guidelines for the application of IUCN Red List of
Ecosystems Categories and Criteria, Version 1.1. Gland, Switzerland.
Botts EA, Skowno AL, Driver A, Holness S, Maze, K, Smith T, Daniels F, Desmet PG, Sink K, Botha M, Nel J, Manuel J (in review)
Integration of South Africa’s threatened ecosystems into conservation planning and environmental policy. Biological Conservation
Dayaram, A., L. Powrie, T. Rebelo, and A. Skowno. (2017) Vegetation Map of South Africa, Lesotho and Swaziland 2009 and 2012: A
description of changes from 2006. Bothalia 47:1-10.
Government Gazette. 2011. National list of ecosystems that are threatened or in need of protection. Department of Environmental
Affairs, Government Gazette 34809:1002, 9 December 2011, Pretoria.
Keith, D. A., Rodríguez, J. P., Rodríguez-Clark, K. M., Nicholson, E., Aapala, K., Alonso, A., Zambrano-Martínez, S. (2013). Scientific
Foundations for an IUCN Red List of Ecosystems. PLoS ONE, 8(5). https://doi.org/10.1371/journal.pone.0062111
Lloyd, J.W., E.C. van den Berg & A.R. Palmer. 2002. Patterns of transformation and degradation in the Thicket Biome, South Africa.
TERU Report 39, University of Port Elizabeth.
Mucina, L. & M.C. Rutherford. 2006. The vegetation of South Africa, Lesotho and Swaziland. Strelitzia 19. South African National
Biodiversity Institute, Pretoria.
Rowland, J. A., Nicholson, E., Murray, N. J., Keith, D. A., Lester, R. E., & Bland, L. M. (2018). Selecting and applying indicators of
ecosystem collapse for risk assessments. Conservation Biology, 1–35. https://doi.org/10.1111/cobi.13107
Skowno, A. L. (2018) Terrestrial habitat modification change map (1990-2014) for South Africa: a national scale, two timepoint, land
cover derived, map of terrestrial habitat modification - NBA 2018 Technical Report. Pretoria, South Africa.
Thompson, M., Vlok, J., Rouget, M., Hoffman, M. T., Balmford, A., & Cowling, R. M. (2009). Mapping grazing-induced degradation in
a semi-arid environment: A rapid and cost effective approach for assessment and monitoring. Environmental Management, 43(4),
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 9
Appendix 1. Extract from Chapter 7 of the Terrestrial Realm Report for the NBA
2018
Chapter 7: Skowno, A.L., Matlala, M.S., Kirkwood, D. & Slingsby. J.A. 2019. ‘Chapter 7: Ecosystem Assessments’ in National Biodiversity Assessment 2018 Technical Report Volume 1: Terrestrial Realm. Skowno, A.L., Raimondo, D.C., Poole, C.J., Fizzotti, B. & Slingsby, J.A. (eds.). South African National Biodiversity Institute, Pretoria.
Ecosystem threat status (Red list of Ecosystems) South Africa is one of several countries to independently develop indicators of ecosystem threat prior to the
IUCN Red List of Ecosystems (RLE) (Keith et al. 2013)(www.iucnrle.org). These indicators met a recognised
need for an indicator similar to the IUCN Red List of Species that could identify risk for higher-levels of
biodiversity organisation such as ecological communities (Keith et al. 2013; Bland et al. 2017).
The South African List of Threatened Ecosystems was conceptualised as a national indicator of ecosystem
conservation status in the early 2000s. From its early applications as a project-based indicator, it progressed
into a legislated national listing of threatened terrestrial ecosystems (RSA 2011, Botts et al. in review) which
entrenched its use in land use planning and decision making (e.g. through the Environmental Impact
Assessment processes). South Africa has also been reporting on the threat status of its ecosystems for more
than a decade, and using this information to focus scarce resources on conservation priorities through a wide
range of government policies (Driver et al. 2004, 2012; Botts et al. in review).
For the NBA 2018, the ecosystem threat assessments were based on the updated national vegetation map
and new ecosystem condition map (based primarily on the land cover change data). Both the 2011 South
Africa method and the new 2017 IUCN RLE methods were implemented with the aim of comparing and
contrasting the results. Overall, the South African method and the IUCN method were similar, but the
benefits of using the IUCN system (i.e. a stronger scientific evidence base than the South African method,
recognition of the resulting RLE by the IUCN and alignment for with international conventions and
assessment processes) tend to outweigh the drawbacks (i.e. deviating from a locally well-established and
accepted method) (Skowno et al. 2018b). Consequently, the NBA 2018 Terrestrial Reference Group decided
that the IUCN RLE approach should be adopted for the NBA 2018 and that the gazetted list of threatened
ecosystems should be updated with the new information as soon as possible.
The IUCN Red List of Ecosystems Framework
Background of the IUCN RLE
The IUCN Red List of Ecosystems is a framework for assessing the risks to ecosystems and identifying where
ecosystems are threatened (Rodríguez et al. 2011). Using the familiar categories from the Red List of Species
(Figure 4), and based on a set of criteria and thresholds developed collaboratively since 2008, the IUCN RLE
was established to ensure that the assessment methods: (i) can be applied systematically across realms and
geographic areas; (ii) are transparent and scientifically rigorous; (iii) are comparable and repeatable; (iv) can
be easily understood by policy makers and the general public; and (v) complement the IUCN Red List of
Threatened Species framework (Rodríguez et al. 2011; Keith et al. 2013; Bland & Keith et al. 2017).
The key concepts and definitions underpinning the RLE have been documented in a number of international
journal publications, notably Nicholson et al. 2009; Rodríguez et al. 2011; Keith et al. 2013, 2015; Bland
et al. 2017b, 2018. There is growing uptake of the IUCN RLE standards (Bland & Keith et al. 2017) with number
of published sub-global assessments (including North America, Philippines, Australia, Colombia, France,
Finland) adopting the RLE approach. Ultimately, national and other sub-global assessments undertaken using
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 10
these international standards will contribute towards establishing a global database of threatened
ecosystems equivalent to the global Red List of Species.
Key Concepts
The goal of the IUCN RLE is to identify ecosystems that are at risk of losing their constituent biodiversity.
While there is substantial evidence that the ecosystem function and services are linked with biodiversity
(Bland & Keith et al. 2017), the relationships between these three facets of ecosystems can be complex.
Consequently, the RLE focusses specifically on risks to biodiversity (Keith et al. 2013). The RLE requires
consistent and clearly defined units of assessments (ecosystem types) that can be delineated spatially, while
at the same time needs to be able to effectively assess risks across widely contrasting ecosystems
(Keith et al. 2013). Vegetation types, in particular, have been suggested as appropriate and consistent units
that represent biodiversity and communities at an appropriate scale for use in the RLE (Keith et al. 2013;
Boitani, Mace & Rondinini 2015). The RLE framework used the concept of ecosystem collapse as the ‘end
point’ of ecosystem decline, this is equivalent to species extinction in the RLS, and is defined operationally as
a ‘transformation of identity, loss of defining abiotic or biotic features and characteristic native biota are no
longer sustained’ (Keith et al. 2013).
Criteria and Thresholds
The risk assessment model for the IUCN RLE is illustrated schematically in Figure 36. Declining distributions
(Figure 5-A) and restricted distributions (Figure 5-B) are considered distributional symptoms of decline; and
degradation of abiotic environment (Figure 5-C) and altered biotic function (Figure 5-D) are considered
functional symptoms of decline. It is possible for these mechanisms to interact and produce additional
symptoms of decline (Keith et al. 2013). The mechanisms in the conceptual model (Figure 5) translate into
five rule-based criteria with thresholds for the distributional and functional symptoms. The final threat listing
for each ecosystem is the worst threat category triggered by any of the criteria (i.e. if an ecosystem is listed
CR under any criteria it is listed CR overall, even if it only scores LC or any other category under all other
criteria).
Figure 4. IUCN RLE threat categories, see glossary of terms of definitions. Source: Bland et al. (2017a).
Figure 5. IUCN RLE framework for assessing the risk of ecosystem collapse. Source: Keith et al. (2013).
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 11
Implementation of the IUCN RLE for the NBA 2018
We applied the IUCN Red List of Ecosystems (RLE) method for the NBA 2018 using a comprehensive
systematic assessment based on IUCN Criteria A&B (criteria linked to spatial configuration and remaining
extent of ecosystems) for all terrestrial ecosystem types (vegetation types). This assessment, referred to as
the ‘core’ assessment, was then supplemented with additional assessments of selected ecosystem types
based on additional data on ecosystem condition including: habitat loss in metropolitan areas, KZN, Western
Cape and Mpumalanga; degradation in the Albany Thicket biome and Western Cape; and degradation from
invasive alien species and overgrazing using data extracted from threatened species assessments.
It is envisaged that the preliminary national RLE resulting from this assessment will be considered as the
baseline for the nation, and that it will be updated as additional information becomes available and be
released annually. Given the general lack of appropriate ecosystem condition data available in South Africa
this base line assessment is likely to have underestimated the risk to numerous ecosystem types – especially
those that are threatened by more subtle ecosystem modification than land clearing. If the threat status of
an ecosystem type is: a) considered an underestimate; or b) if the data used in the assessment is considered
inaccurate or inadequate; or c) if a researcher can develop new datasets to address additional criteria for
selected ecosystems; then further supplementary assessments should be undertaken. The core assessment
will be updated when updated national land cover change data becomes available.
Input data
The national land cover change dataset (Chapter 3) and the national vegetation map (Chapter 4) provided
the ecosystem assessment units and the primary ecosystem condition input to the RLE analysis. Additional
land cover data was sourced for Gauteng (2011), City of Cape Town (2017), Nelson Mandela Bay Metropolitan
Municipality (2015), Mpumalanga (2017), the Western Cape (2016) and KwaZulu-Natal (2011) (Table 6);
these datasets were used to perform supplementary assessments for Criteria A3. The threatened species
database (SANBI, Threatened Species Unit) was used to identify selected limited range ecosystems (Criteria
B) that are experiencing ongoing decline due to habitat loss, overgrazing or invasive plant species. Ecosystem
degradation data for the Albany Thicket biome, Little Karoo region and the Western Cape allowed for a
supplementary assessment of these regions using Criteria D3 (Table 6).
Table 6. Input data sources for the Red List of Ecosystem analysis.
Assessment Dataset Description Reference
All assessments
Terrestrial ecosystem type map
Vegetation map of South Africa, Lesotho and Swaziland 2018 version 6. Polygon feature geodatabase developed and curated by SANBI.
South African National Biodiversity Institute (2006). The Vegetation Map of South Africa, Lesotho and Swaziland, Mucina, L., Rutherford, M.C. and Powrie, L.W. (Editors), Version 2018.6b.
Core assessment: Criteria A3, A2b, B1, B2
National land cover
Land cover change raster developed by SANBI with two timepoints 1990, 2014. Based on national land cover products by GeoTerra Image 2015.
Skowno AL (2018) Terrestrial habitat modification change map (1990-2014) for South Africa: a national scale, two timepoint, land cover derived, map of terrestrial habitat modification - NBA 2018 Technical Report. Pretoria, South Africa. GeoTerraImage (2015) Technical Report: 2013/2014 South African National Land Cover Dataset version 5. Pretoria, 53 pp. GeoTerraImage (2015) Technical Report: 1990 South African National Land Cover Dataset version 5.2. Pretoria, 63 pp.
Supplementary: Criterion A3
City of Cape Town natural vegetation remnants map
2017 Vegetation remnants map produced by City of Cape Town based on remote sensing and in field validation of condition. Provided as a polygon feature geodatabse.
City of Cape Town (2017). Current Indigenous vegetation [Data file]. Retrieved from City of Cape Town Open Data Portal https://web1.capetown.gov.za/web1/opendataportal
Gauteng land cover
A composite raster land cover product that combines very high resolution (2.5m) urban land cover with high resolution (1om) rural land cover for the province.
Natural areas map from the municipal bioregional planning process, with combination of desk top and field validated ecological condition. Provided as a polygon shapefile.
Stewart, W.I. and Jorgensen, P.J. 2016. Updating of Systematic Biodiversity Plan and development and publication of Bioregional Plan for the Nelson Mandela Bay Municipality: NMBM 2015 Landcover. SRK Consulting, South Africa.
KwaZulu-Natal land cover
2011 provincial raster land cover product (20m resolution) validated by provincial conservation authorities.
Jewitt D, Goodman PS, Erasmus BFN, O’Connor TG, Witkowski ETF (2015) Systematic land cover change in KwaZulu-Natal, South Africa: Implications for biodiversity. South African Journal of Science, 111, 0–9.
Mpumalanga land cover
2017 provincial raster land cover product (10m resolution) validated by provincial conservation authorities.
Evidence of ongoing decline for selected limited range ecosystems with very high numbers of threatened plant species – drawn from Red List of Species assessments.
Threatened species database of South Africa (SANBI, Threatened Species Unit).
Supplementary assessment: Criterion D3
Western Cape ecosystem degradation data
2015 provincial raster land cover and ecological condition product (10m resolution) validated by provincial conservation authorities.
2002 biome-wide Landsat TM 5 based raster ecosystem degradation product (30m). Developed and field validated as part of the Subtropical Thicket Ecosystem Project (STEP) by the Agricultural Research Council.
Lloyd JW, Van den Berg EC, Palmer AR (2002) Patterns of transformation and degradation in the Thicket Biome, South Africa. Terrestrial Ecology Research Unit, University of Port Elizabeth.
Little Karoo degradation data
2005 MODIS based degradation map of Little Karoo region.
Thompson M, Vlok J, Rouget M, Hoffman MT, Balmford A, Cowling RM (2009) Mapping grazing-induced degradation in a semi-arid environment: A rapid and cost effective approach for assessment and monitoring. Environmental Management, 43, 585–596.
Core assessment
Criteria A2b and A3 – historical and future reductions in geographic range
The ecosystem type data (vegetation map version 2018) and the ecosystem condition data (land cover based)
were cross tabulated within a geographic information system and changes in natural extent from the
reference condition (circa 1750) to 1990 and 2014 were computed for each ecosystem type. The remaining
natural extent of each ecosystem type in 2014 was subtracted from the historical reference extent (circa
1750) and expressed as a percentage of the historical extent; allowing for the application of the thresholds
for Criterion A3 (historical reductions in geographic range). The absolute rate of decline in natural habitat
between 1990 and 2014 (Equation 1) was used to estimate the natural extent of each ecosystem type in 2040
(Equation 2), this projected value was then subtracted from the 1990 extent and expressed as a percentage
of the 1990 extent; allowing for the application of the Criterion A2b (past-present-future reductions in
geographic range).
Equation 1: Absolute Rate of Decline1: 𝐴𝑅𝐷 =𝐴𝑟𝑒𝑎1990 − 𝐴𝑟𝑒𝑎2014
1 Absolute Rate of Decline ARD is the term used by the IUCN Red List of Ecosystems Guidelines; it is equivalent to rate of habitat loss,
and to rate of reduction in ecosystem extent used in previous chapters. ARD / rate of habitat loss underpin the ecosystem extent indicators discussed in Chapter 1 and 3.
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 13
Criteria B1i and B2i – Restricted geographic range
The first step for the assessment under this criterion was to combine the habitat modification data for 2014
with the ecosystem type data to produce an ‘ecosystem remnants’ layer circa 2014. This layer (in geotiff
format) was used to compute the Extent of Occurrence (EOO) and Area of Occupancy (AOO) for each
ecosystem type with the package [redlistr] (Lee & Murray 2017) within the statistical software R (R Core Team
2014). Ecosystem types only qualify for consideration under Criterion B if they are experiencing ongoing
declines in extent or condition (observed or inferred). For the core assessment, an absolute rate of decline
(ARD, Equation 1) threshold of 0.4%/y was used to identify ecosystems qualifying for Criterion B in terms of
ongoing decline. Ecosystems with ARD above this threshold have lost approximately 10% of their natural
remaining extent in the last 25 years. This then allowed for the assessment of Sub-criterion B1 (i) and Sub-
criterion B2 (i) for all qualifying ecosystem types (Table 7).
Supplementary assessments
To complement the core assessment a number of additional datasets were compiled to ensure the ecosystem
risk assessments were based on the best available data. This is a first version of the RLE and going forward
this is an approach that will allow for reassessments of selected ecosystem types as new and improved data
is collected or additional existing data comes to light. The supplementary assessment used Criteria A, B and
D.
Criterion D - Disruption of biotic processes (supplementary)
The Sub Tropical Ecosystem Project (STEP) and Little Karoo (LK) ecosystem degradation datasets (Lloyd, Van
den Berg & Palmer 2002; Rouget et al. 2003; Thompson et al. 2009) were used to assess the ecosystem types
of the Albany Thicket biome and Little Karoo region using Criterion D3 (biotic disruption since 1750) (Table
7). This criterion uses both the severity of disruption (50%, 70% or 90%) and the extent of the disruption
(50%, 70% or 90%) to categorize ecosystems. The STEP and LK degradation class ‘severe’ was considered as
90% severity due to large scale disruption of a wide range of biotic process including vegetation structure,
species composition, richness, biomass (Lloyd, Van den Berg & Palmer 2002; Thompson et al. 2009). The
extent of severely degraded land within in each ecosystem type was expressed as a percentage of the natural
remaining extent and the thresholds as per Table 7 were applied.
Criterion A3 - Historical reductions in geographic range (supplementary)
High resolution and high confidence land cover data exist for certain regions within South Africa including
Gauteng Province, City of Cape Town, Nelson Mandela Bay Metro, Mpumalanga, the Western Cape Province
and KwaZulu-Natal Province (Table 6). The ecosystem type data (vegetation map version 2018) and the high
resolution land cover data were cross tabulated within a geographic information system and changes in
natural extent from the reference condition (circa 1750) were computed for each ecosystem type. The
remaining extent of each ecosystem type was expressed as a percentage of the original extent of the
ecosystem type (circa 1750), allowing for application of Criteria A3 (historical reductions in geographic range).
Criteria B1iii and B2iii – Restricted geographic range (supplementary)
A key challenge in the application of the RLE is the poor availability of spatially explicit ecosystem degradation
data. As a result, the risk of collapse of many ecosystem types may have been underestimated in the core
assessment. A supplementary assessment of Criterion B was undertaken using the threatening processes
data from the Threatened Plant Species Database (SANBI Threatened Species Unit), the most reliable source
of data on functional symptoms of decline in South Africa. For the supplementary assessment of Criterion B,
the qualifying criteria (i.e. evidence of biotic disruption) was a quantitative assessment of threatening
processes listed for the threatened species occurring in each ecosystem type. To do this each threatened
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 14
plant species was assigned to an ecosystem type or ecosystem types using their spatial position and
descriptions of preferred habitat (personal communication with SANBI Threatened Species Unit). We then
calculated the number of species per ecosystem type that are threatened by a) poor rangeland management
(over grazing), b) invasive alien species and c) inappropriate fire management. The qualifier for biotic
disruption Criteria B1iii and B2iii in the supplementary assessment was set to: ecosystems that contained >
40 threatened plant species, of which > 60% were threatened due to major biotic disruptions. This is a
preliminary solution while additional data on biotic disruption, severity and extent are collected.
Table 7. full list of IUCN RLE criteria and thresholds (Rodríguez et al. 2011); for the list of criteria used in the South African implementation of the RLE see Table 8.
Table 8. IUCN RLE criteria and thresholds used in the South African assessment 2018.
Criteria & Sub-criteria CR EN VU
Criteria A: Reduced geographic distribution
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 15
Sub-criterion A2b - Loss of habitat over a 50 year period including past present and future For the NBA 2018, the absolute rate of decline in natural habitat between 1990 and 2014 (Equation 1) was used to estimate the natural extent of each ecosystem type in 2040 (Equation 2), this projected value was then subtracted from the 1990 extent and expressed as a percentage of the 1990 extent; allowing for the application of the Criterion A2b (past-present-future reductions in geographic range).
≥ 80% ≥ 50% ≥ 30%
Sub-criterion A3 – Historical loss of habitat (since ~1750) For the NBA 2018, the remaining natural extent of each ecosystem type in 2014 was subtracted from the historical reference extent (circa 1750) and expressed as a percentage of the historical extent; allowing for the application of the thresholds for Criterion A3 (historical reductions in geographic range). Equivalent supplementary assessments utilised higher resolution land cover products available for KwaZulu-Natal province, Mpumalanga province, Western Cape province and three large metropolitan areas.
≥ 90% ≥ 70% ≥ 50%
Criteria B: Restricted distribution & continuing declines in geographic distribution
Sub-criterion B1 (i) - Extent of a minimum convex polygon (km2) enclosing all
occurrences (EOO) & an observed or inferred continuing decline in spatial extent. For the NBA 2018, the absolute rate of habitat loss was used to identify ecosystems with significant ongoing decline in the extent of natural habitat (> 0.4%/y). Supplementary assessments used expert input and the threatened species database to identify restricted distribution ecosystems with very high levels of biotic disruption from over grazing, invasive species and poor fire management - B1(iii).
≤ 2 000 km2 ≤ 20 000
km2
≤ 50 000
km2
Sub-criterion B2 (i) - The number of 10×10 km grid cells occupied (AOO) & an observed or inferred continuing decline in spatial extent. For the NBA 2018, the absolute rate of habitat loss was used to identify ecosystems with significant ongoing decline in the extent of natural habitat (> 0.4%/y). Supplementary assessments used expert input and the threatened species database to identify restricted distribution ecosystems with very high levels of biotic disruption from over grazing, invasive species and poor fire management - B2(iii).
≤ 2 ≤ 20 ≤ 50
Criteria D: Disruption of biotic processes or interactions
Sub-criterion D3 – Disruption of biotic processes, since 1750, based on change in a biotic variable affecting a fraction of the extent of the ecosystem and with relative severity, as indicated by the table on the right. For the NBA 2018, ecosystem degradation data from the Albany Thicket biome and Little Karoo region were used. The severely degraded class in these datasets was considered to be ≥ 90% severity, the extent of severe degradation was expressed as a percentage of the remaining habitat circa 2014.
Relative severity (%)
Ext
ent (
%)
≥ 90 ≥ 70 ≥ 50
≥ 90 CR EN VU
≥ 70 EN VU
≥ 50 VU
Results of the ecosystem threat assessment
The first implementation of the IUCN RLE for South African terrestrial ecosystems (458 vegetation types) for
the NBA 2018 resulted in the listing of 35 Critically Endangered, 39 Endangered and 29 Vulnerable ecosystems
(Table 9) (Figure 6). While eight percent of ecosystem types are Critically Endangered, this amounts to less
than one percent of the extent of natural remaining habitat in South Africa. Endangered ecosystems make
up 8.5% of ecosystems by type and 3% by extent remaining. Vulnerable ecosystems make up 6.3% of
ecosystem by type, amounting to 4% of the natural remaining habitat of South Africa (Table 9) (Figure 7). The
most influential criterion in the RLE assessment was Criterion B1 (restricted distribution & continuing declines
in geographic distribution) which contributed to the listing of 53/103 ecosystem types and Criterion A3
(historical loss of habitat) which contributed to the listing of 28/103 ecosystem types. The supplementary
assessment of Criterion B1 (iii) using the threatened species pressures database contributed to the listing of
25/103 ecosystem types, of which 12 were listed purely due to this criterion. Criterion D3 (biotic disruption
– based on ecosystem degradation) resulted in the listing of only one (Vulnerable) ecosystem type.
Table 9. Summary of the assessment outcomes; including the number of ecosystem types per category & proportion of the natural areas remaining per category.
Category (IUCN RLE) Number of ecosystems
Extent of natural Habitat (km2)
Percentage of natural remaining habitat of SA
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 16
Critically Endangered 35 5 904 0.6%
Endangered 39 28 982 3%
Vulnerable 29 42 459 4.4%
Least Concern 355 882 820 92%
Total for South Africa 458 960 167 100%
Figure 6. Map showing the distribution of threatened ecosystems according to the IUCN Red List of Ecosystems. The map shows the historical extent of the ecosystem types (based on the National Vegetation Map 2018). The inset graph shows the percentage of ecosystem types that falls within each threat category.
Results per biome
The Fynbos biome has the highest number of threatened ecosystems types (53), followed by Grassland (21)
and Savanna (11) and these make up 20%, 24% and 3% of the natural remaining habitat of the biome
respectively (Figure 8, Table 10). Of the six of the ecosystems types making up the Indian Ocean Coastal Belt
biome, 4 are threatened and 62% of the natural habitat remaining in the biome is threatened. The arid
regions of the country have less threatened ecosystems (by type and by remaining extent); the Succulent
Karoo has two threatened ecosystems (amounting to 0.2% of the natural habitat) and the Nama-Karoo has
no threatened ecosystems. The full terrestrial threatened ecosystem database, including information on land
cover change and the RLE criteria for each ecosystem type, is available online on the Biodiversity GIS website
(http://nba.sanbi.org).
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 17
Figure 7. Map showing the natural remaining extent (circa 2014) of threatened ecosystems according to the IUCN Red List of Ecosystems. The inset graph shows the percentage of the total natural habitat remaining in South Africa (960 167 km2) that falls within each threat category.
Table 10. Percentage natural remaining habitat within each IUCN RLE threat category, listed per biome. The number of ecosystem types per threat category, per biome is shown in parenthesis.
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 18
Figure 8. Threatened ecosystem types per biome, showing (a) the percentage of ecosystem types per biome that fall within each threat category, and (b) the percentage of the total natural habitat remaining in each biome that falls within each threat category (Critically Endangered – CR; Endangered – EN; Vulnerable – VU; Least Concern – LC).
Provincial summary
Threatened ecosystems are not evenly distributed across South Africa’s provinces. While a large proportion
of the remaining natural habitat in Gauteng (45%), KwaZulu-Natal (30%) and Mpumalanga (30%) is
threatened, a much smaller percentage is listed as Critically Endangered (3%, 1% and 0% respectively) (Figure
9, Table 11). This pattern is mirrored in Limpopo, Free State, Eastern Cape and North West provinces. The
Western Cape has a slightly different pattern with Critically Endangered, Endangered and Vulnerable
ecosystem types are being more even in terms of extent. The results of the ecosystem assessment are closely
linked to the land cover change patterns of the provinces. The high population density of Gauteng, and high
agriculture potential and high population density of KwaZulu-Natal and Mpumalanga are the drivers of the
high rates of habitat loss. Despite the high number of threatened ecosystems in the Western Cape (54), linked
to high ecosystem diversity of the Fynbos biome, only 11% of the natural remaining ecosystem extent of the
province is threatened.
Table 11. Table showing the percentage of the natural remaining habitat in each province that falls with each IUCN RLE category; in parenthesis is the number of ecosystem types per category per province (note these do not sum to a national number of threatened ecosystems as ecosystem types cross provincial boundaries.
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 19
Figure 9. Threatened ecosystems per province, showing (a) the percentage of ecosystem types per province that fall within each threat category, and (b) the percentage of the total natural habitat remaining in each province that falls within each threat category (Critically Endangered – CR; Endangered – EN; Vulnerable – VU; Least Concern – LC).
Ecosystem threat status trends
The IUCN RLE methodology relies heavily on land cover change data (which inform Criteria A2b, A3, B1 and
B2). The two time point data available in South Africa are well suited to the RLE assessment but do not allow
for a complete application of the RLE to the earlier time points (a retrospective analysis). A partial application
of the RLE to the 1990 time point is possible, but it would be restricted to Criteria A3 (historical loss of habitat)
only. The national land cover of South Africa is due for an update in 2018, and on the release of this data the
RLE will be updated. This will then lay the foundation for a Red List Index for Ecosystems, which will track
changes in ecosystem threat status over time. As such, this RLE for South Africa represents a new baseline
for threatened ecosystems.
A direct comparison of this 2018 RLE analysis with the 2011 National List of Threatened Terrestrial
Ecosystems (RSA 2011) is of limited utility (Table 12). The input datasets have changed (i.e. a new vegetation
map, and new land cover data have been used), the input data have expanded (i.e. there is land cover change
data available for the first time, unlocking many dormant criteria), and the threat assessment methodology
has changed [i.e. the IUCN RLE framework and guidelines (Bland & Keith et al. 2017) have been released, and
the NBA 2018 utilises this framework]. Changes in ecosystem status between 2011 and 2018 could then be
attributed to any one or a combination of these factors.
Table 12. Comparison of the results of the 2018 Red List of Ecosystems and the 2011 National List of Threatened Terrestrial Ecosystems [note: the methods and input data were not the same at each time point, so this does not represent a trend analysis]. The table includes the number of ecosystem types per category and the proportion of the natural habitat of South Africa within each category. The 2011 assessment included 438 vegetation types and 108 ‘special ecosystem types’; the 2018 assessment was applied to an updated vegetation map with 458 units.
Category (IUCN RLE)
2011 2018
Number of ecosystems
Percentage of natural habitat of SA
Number of ecosystems
Percentage of natural habitat of SA
Critically Endangered 53 1% 35 0.6%
Endangered 64 2% 39 3%
Vulnerable 108 7% 29 4.4%
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 20
Ecosystems of special concern
The IUCN RLE is a risk assessment framework for
consistently identifying ecosystems that are at risk of
collapse. Since the RLE is designed to be applied across
realms and across the globe, there are certain local
ecosystems that do not meet the thresholds for the
threat categories but are considered ‘of special
concern’ for a number of reasons. This concept has
been successfully applied to the Red List of Species in
South Africa, including range restricted rare species of
the mountainous regions in particular. For the NBA
2018, all Forest ecosystem types (which, in South
Africa are naturally rare, of limited extent and highly
fragmented) are classified as ecosystem of special
concern (Figure 10). Dedicated legislation is in place to
protect natural forests in South Africa (e.g. National
Forests Act (Act 84 of 1998)), and assigning these
ecosystems to the category Ecosystems of Special
Concern highlights this need for protection without interfering with the risk assessment framework of the
IUCN RLE. This does not prevent the listing of threatened Forest ecosystem types if the IUCN RLE criteria are
met, and additional data on forest condition (using forest resource assessments for example) is a
conservation priority. In future assessments, special ecosystem types in other biomes will be considered
based on factors such as exceptional species diversity and restricted range / endemism.
Ecosystem threat status limitations
The key shortcoming of all of these ecosystem threat status assessments in the terrestrial realm is that we
lack appropriate data on ecosystem condition, land degradation and biotic disruption of ecosystems. This
means that in many regions the baseline ecosystem assessment reported here will underestimate the risk of
collapse. We have reasonable confidence that the ecosystems that are listed as threatened are genuinely at
risk of collapse – but there are many ecosystems that are at risk that which are not on currently listed as
threatened – purely as a result of lack of data. Some (outdated) data is available for the thicket biome, but
in other biomes it is a very challenging problem that will need significant focussed research. One aspect of
degradation that should be possible to map accurately, and therefore use in ecosystem assessment, is
distribution and abundance of alien invasive species. For woody plants that reach high abundances and high
visibility, this certainly seems possible in the near future. Another challenge is that for many of the ecosystem
types there is no clear model of ecosystem function against which we can measure biotic disruption or
degradation. This makes calibrating models of ecosystem condition difficult.
A further shortcoming of this assessment is that it relies heavily on land cover data collected in 2013/2014,
making the data over three years old. This is not ideal and, as automated and global scale remote sensing
becomes more accessible, it is hoped that future assessments will not suffer from this long time delay. As
soon as new land cover data become available (scheduled for 2018 release by the Department of
Environmental Affairs) SANBI has set up a system to automatically update the baseline RLE (though there are
many steps for which expert validation are required). The aim is to reduce this time lag to less than one year.
Figure 10. Ecosystem of special concern. Forest ecosystem types that are not considered threatened under the IUCN RLE framework but warrant special protection and monitoring.
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 21
Ecosystem types with distribution ranges beyond South Africa’s borders
Assessing an ecosystem type across a portion of its global range would result in a partial RLE assessment that
may not reflect the true risk of collapse for the ecosystem. The vegetation map that forms the basis of the
Red List of Ecosystems for South Africa also covers the neighbouring countries of Lesotho and Swaziland. As
a result, ecosystem types that are distributed across these particular international boundaries can be
considered to have been assessed comprehensively. For neighbouring countries such as Namibia, Botswana,
Zimbabwe and Mozambique, no comparable vegetation maps exist, and types that cross these borders
cannot be assessed across their full range at present. For the most part, however, the terrestrial ecosystem
types that occur can only in South Africa and can be considered endemic (406/458 types [89%] are endemic),
and the RLE presented above thus represents an ecosystem-wide assessment for the majority of types.
There are six terrestrial ecosystem types that are listed as Threatened but are likely to occur extensively
outside of South Africa, Lesotho and Swaziland (Table 13). Of these threatened and non-endemic types that
extend beyond the borders of South Africa, Lesotho and Swaziland, three fall into the Savanna biome, two in
the Indian Ocean Coastal Belt and one Forest biome. Efforts are underway to align vegetation maps across
national boundaries in southern Africa, and when this is achieved these “cross border” units will be
comprehensively assessed.
Table 13. Non-endemic ecosystem types included in the Red List of Ecosystems – these types are only partially assessed and their extent and condition outside of South Africa needs to be determined before a final assessment of their status can be made.
Ecosystem type Biome RLE Status
Lebombo Summit Sourveld Savanna Endangered
Lowveld Riverine Forest Forests Vulnerable
Maputaland Coastal Belt Indian Ocean Coastal Belt Endangered
Maputaland Wooded Grassland Indian Ocean Coastal Belt Endangered
Muzi Palm Veld and Wooded Grassland Savanna Critically Endangered
Western Maputaland Clay Bushveld Savanna Endangered
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 22
Appendix 2. Comparison of 2011 methods and RLE methods employed in 2018
Table A2-1.The criteria used in the testing phase for the NBA Terrestrial Ecosystem Threat status Assessment.
Criteria Description IUCN RLE version 2
SA 2011 NEMBA
IUCN A2b Projected extent remaining (2040) based on rate of decline between 1990 and 2014
IUCN A3core, Extent remaining at most recent time point (2014) (based on national land cover)
IUCN A3city Extent remaining at most recent time point (2014) (based on fine scale city land cover for Cape Town, PE, Durban, Gauteng)
IUCN A3kzn Extent remaining at most recent time point (2011) (based on KZN land cover)
IUCN B1_10 Limited extent (EOO) with 0.4% / y rate of decline qualifier (2000, 20 000 and 50 000 km2 thresholds)
IUCN B2_10 Limited distribution (AOO) with 0.4% / y rate of decline qualifier (2000, 20 000 and 50 000 km2 thresholds)
IUCN D3degsev
Extent severely degraded based on STEP and Little Karoo and Western Cape Fine Scale Plans degradation data
IUCN B1ThrSp Limited extent (EOO) with strong evidence of ongoing decline and degradation based on threatened species database (>40 threatened species where >30% of these species are threatened by ongoing degradation)
SA A1 Extent remaining at most recent time point (based on national land cover and using biodiversity targets as thresholds)
SA A2 Land degradation: not considered for most ecosystems in 2011. Considered for selected forest ecosystems based on expert workshops in 2011
forest only
SA B Projected extent remaining (2040) (based on rate of decline between 1990 and 2014 and using biodiversity targets as thresholds) (not considered in NEMBA list)
SA C Limited extent applied without qualifier of decline in 2011 SA D1 Number of threatened species per ecosystem type
SA F Special ecosystems and Critical Biodiversity Areas
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 23
Table A2-2. Illustration of the similarities of the IUCN RLE framework and South African Threatened Ecosystem Listing framework.
Terrestrial ecosystem threat status assessment 2018 – comparison with 2011 assessment 24
Appendix 3. List of terrestrial ecosystem types assessed in 2018 compared with 2011 NEMBA list
Northern Zululand Mistbelt Grassland EN B1 higher threat category - habitat loss and limited distribution, includes some SA Criterion F ecosystem extent
Southern KwaZulu-Natal Moist Grassland EN B1 higher threat category - habitat loss and limited distribution, includes some SA Criterion F ecosystem extent