Impact of invasion by Prosopis juliflora on plant communities

Tropical Ecology 55(1): 33-47, 2014 ISSN 0564-3295 © International Society for Tropical Ecology www.tropecol.com

Impact of invasion by Prosopis juliflora on plant communities in arid grazing lands

SURESH KUMAR* & MANISH MATHUR

Division of Natural Resources and Environment Central Arid Zone Research Institute, Jodhpur 342003 Rajasthan, India

Abstract: Impacts of invasion of a ligneous weed, Prosopis juliflora, in plant communities of reserve forests, protected forests, unprotected forests and open grazing lands in Jamnagar district in arid coastal areas of Gujarat state of India were assessed. Sites invaded by P. juliflora had different ligneous plant composition with lower order seral species being dominant. In all landuses, Prosopis-invaded sites had more species richness, diversity, and evenness. However, increase in species richness was due to occurrence of more weedy species along with Prosopis juliflora. Even amongst the protected and undisturbed sites, dominance of late successional species, e.g., Acacia senegal, Maytenus emarginata, Zizyphus nummularia and Acacia nilotica, was less at sites with Prosopis juliflora than at sites without it. Density of Commiphora wightii, an endangered species, decreased with increasing density of P. juliflora. Invasion of P. juliflora has thus demonstrable adverse impacts on plant communities in arid grazing lands.

Resumen: Se evaluaron los impactos de la invasión de una maleza leñosa, Prosopis

juliflora, en las comunidades vegetales de bosques de reserva, bosques protegidos, bosques no protegidos y tierras de pastoreo abiertas en el distrito Jamnagar, en áreas costeras áridas del estado Gujarat, India. Los sitios invadidos por P. juliflora tuvieron una composición de planas leñosas diferente, siendo dominantes las especies serales de orden bajo. En todos los usos del suelo, los sitios invadidos por Prosopis tuvieron una riqueza de especies, diversidad y equitabilidad mayores. Sin embargo, el incremento en la riqueza de especies se debió a la presencia de más especies de malezas junto con Prosopis juliflora. Aun en los sitios protegidos y no perturbados, la dominancia de especies sucesionales tardías, e.g., Acacia senegal, Maytenus emarginata, Zizyphus nummularia y Acacia nilotica, fue menor en sitios con Prosopis juliflora que en sitios donde la especie estuvo ausente. La densidad de Commiphora wightii, especie en peligro de extinción, decreció con el aumento en la densidad de P. juliflora. La invasión de P. juliflora tiene impactos adversos demostrables en las comunidades vegetales en tierras áridas de pastoreo.

Resumo: Os impactes da invasão de uma invasora lenhosa, a Prosopis juliflora, em

comunidades vegetais de reservas florestais, florestas protegidas, florestas desprotegidas e pastagens abertas foram avaliadosno distrito de Jamnagar em zonas costeiras áridas do estado de Gujarat na Índia. As estações invadidas por P. juliflora tinhamuma composição de espécies lenhosas diferentesde menor ordem seral que fossem dominantes. Em todos as formas de uso do solo, os que se encontravam invadidos pela Prosopis apresentavam maior riqueza específica, diversidade e equitatividade. No entanto, o aumento na riqueza específica era devido à ocorrência de mais espécies daninhas juntamente com a Prosopis juliflora. Mesmo entre os locais protegidos e não disturbados, a dominância de espécies do estágio final da sucessão, como, por exemplo, a Acacia senegal, a Maytenus emarginata, Zizyphus nummularia e Acacia nilotica,

*Corresponding Author; e-mail: [email protected]

34 INVASION BY PROSOPIS JULIFLORA

foi menor em locais com Prosopis juliflora do que em locais sem ela. A densidade de Commiphora wightii, uma espécie em risco de extinção, diminuiu com o aumento da densidade de P. juliflora. Os impactes negativos da invasão de P. juliflora sobre comunidades vegetais em pastagens de zonas áridas ficaram assim demonstrados.

Key words: Invasion, Prosopis juliflora, arid vegetation, diversity.

Nomenclature Follows Shah, G. L. (1978).

Introduction

Invasion of woody perennials in grazing lands has been viewed both positively and negatively, positively as a source of browse and shelter to grazing animals, and negatively as competitors for nutrients, water, and space with existing vege-tation (Inderjit 2005). Both schools of thought have been vigorously pursued, the former from the perspective of silvi-pastoral and agro-forestry systems (Huxley 1999), and the latter from the perspective of population ecology. Amongst woody perennials invading grasslands, there are some species that are considered more harmful than useful. One such species is Prosopis juliflora. Geesing et al. (2004) mentioned that studies on the effects of P. juliflora on native flora are very rudimentary. Though negative and positive changes in number and composition of plant species are known, it has not been possible to isolate/separate the impact of invasion by P. juliflora from that of other forms of environmental degradation like overgrazing, human activity, and cutting, etc. Geesing et al. (2004) further added that impact of P. juliflora invasion on plant and animal diversity was still inadequately understood. An attempt has been made in the present exercise to understand these issues of the impact of P. juliflora on bio-diversity.

Prosopis juliflora was introduced into the Indian desert in 1913 by the erstwhile king of the princely state of Marwar mainly to stabilize sand dunes for stopping desert spread (Muthana & Arora 1983). However, it has now spread across all land use types in almost all the districts of western Rajasthan and the adjoining state of Gujarat. Its spread has been the result of large scale planting by forest departments between the early 1960s and the 1980s. Though its plantation is now allowed only on problematic rocky/saline sites, the exten-sive areas previously occupied by it are foci of seed dispersal. Consequently, it has now found roots in the sprawling grasslands of coastal Gujarat. This

investigation is a part of a larger study on mapping these grasslands in Jamnagar district through remote sensing. Mapping of these grasslands (Kumar et al. 2006) revealed that 24 % of their area is invaded by P. juliflora. That P. juliflora has become a weed occupying vast expan-ses of arid and semi-arid zones was also concluded by Pasiecznik et al. (2001). It causes the decline of forage biomass drastically, thus affecting the livelihood of millions of grazers. Its dispersal is mainly by livestock who relish its pods and pass out seeds treated with gastric acids, which then germinate easily. Its allelopathic impacts on pearl millet, sorghum, and sesame are well known (El Fadl 1997), even though its leaf litter reportedly enhances crop biomass. Most often, invasion by P. juliflora coupled with anthropogenic and environ-mental degradation together affect a site’s native vegetation. In order to isolate impacts of invasion from impacts of anthropogenic and/or environ-mental factors, sites free from such impacts need to be studied. The impact of P. juliflora on plant composition in sites under complete protection would be a result of P. juliflora invasion only and would not be compounded by any anthropogenic /environmental effects. This could be investigated by either of two ways: 1. Experimentally introducing P. juliflora into

protected and unprotected sites of the same habitat type and sequentially recording the impacts on native vegetation.

2. Comparing the composition, diversity, and dominance of vegetation invaded by P. juliflora with that which is free from P. juliflora at both protected and unprotected sites of the same habitat type. In this study we adopt the second of the two

approaches to investigate the effects of P. juliflora on vegetation composition. Unprotected sites ad-joining the protected sites were not selected for sampling because fence lines of protected sites hinder free traversing of animals causing extreme degradation in adjoining sites. This phenomenon is

SURESH & MATHUR 35

Fig. 1. Location Map of Jamnagar District.

also known as the near-boundary over-utilization effect. Hence we selected protected and un-protected habitats that were similar but located slightly away from each other. Both protected and unprotected sites invaded by P. juliflora, as well as those that were un-invaded were sampled to understand the effects of P. juliflora under diffe-

rent land uses on the following characteristics of native vegetation: (i) composition, (ii) dominance, (iii) diversity, and (iv) concentration of dominance of other woody perennials especially browse species and endangered species. This is in line with some of the important research directions pointed out by Byers et al. (2001) while studying impact of invasive species.


Material and methods

Study site This study was carried out in Jamnagar

district (latitude 21º 47’ to 22º 58’ longitude 68º 57’ to 70º 40’) in the northwestern part of the Gujarat state of India (Fig. 1). Its terrain is uneven, marked at places by hill ranges, with the Gulf of Kutch in the north, and extensive ranges of sand dunes along the coast in the north and the west. The district is a water scarce area with stony/rocky gravely soils. The torrential nature of rainfall generates 40 - 50 per cent of the rain as runoff, which quickly flows away through a well-integrated drainage system to the sea. Climate of the district is arid with a mean moisture index of – 67.5. Monsoon normally sets in during the first week of July. The average annual rainfall varies from 338 mm at Dwarka (Okha) in the north-western part to 666.5 mm at Dhrol in the south-eastern part of the district. The average number of rainy days (i.e., days with 2.5 mm rainfall or more) in a year in the district varies from 13.6 at Dwarka to 28.1 at Jam Jodhpur. In summer the tempe-rature reaches up to 40.3 ºC. During winter the mean air temperature varies between 10.6 ºC and 28.8 ºC. Relative humidity is very high and ranges from 62 to 82 percent.

Sampling design Using Survey of India (SOI) topographical

sheets and satellite data of IRS 1C LISS III, both at 1:50000 scales, combined with ground truthing, grasslands with and without P. juliflora, forests, croplands, and other land use categories were mapped. Finalized mapped data were processed in GIS using ARC/INFO package to generate carto-graphic output including areas of each mapped category. From these mapped units (Fig. 2), some 37 grasslands representing protected sites (equivalent to reserve forest) called ‘reserve vidis,’ unprotected sites called ‘unreserved vidis,’ protected forests, and unprotected open grazing lands were selected for detailed sampling. ‘Vidi’ is a local name for an area of natural grasses, shrubs, and trees in a silvi -pastoral system of vegetation. At each site vegetation was sampled in ten 10 x 10 m quadrats abutting each other (Kent & Cocker 1992). Number of individuals of each ligneous species was counted in these quadrats.

Data analysis These data were analyzed for relative impor-

tance value (RIV) as described by Curtis &

McIntosh (1950). RIV of all species from the four habitat types are given in Appendix Table 1a-e, while species with the highest RIV in different habitats are summarized in Table 1. The RIV data were further analyzed for richness, dominance concentration and to estimate the Shannon-Wiener index (H′) following Ludwig & Reynolds (1988). Richness is the total number of ligneous species present in a 0.1 ha sample area at each site. Domi-nance concentration (DC) is calculated by Simp-son’s index (λ) (Simpson, 1949). It is calculated as follows:

DC = ∑ pi2

where, pi is the proportion of individuals of the ith species. Its values range from 0 < DC ≤ 1, because its lowest value cannot be zero. Lower DC indi-cates sharing of dominance by many species. Higher DC values denote dominance of one (or a few) species indicating unequal sharing of resources.

Diversity was calculated using Shannon and Wiener index as follows:

H′ = -∑ pi loge pi Shannon index is highly influenced by rare

species. Value of this index varies from 1.5 to 3.5 and rarely surpasses 4. Higher value indicates more diversity and vice-versa.

Trends of all the above parameters were compared in sites with and without invasion of P. juliflora, and are discussed below.

Results

Composition of vegetation at sites with and without P. juliflora

Non-reserve vidis without P. juliflora had Acacia ferruginea, A. catechu, A chundra, A. nilotica, Euphorbia caducifolia, and Lycium barbarum. These species were absent in non-reserve vidis with P. juliflora. All these species are compo-sitional elements of climax formation of the tropical dry deciduous forest type (C/E-3; Champion & Seth 1968). On the other hand, a few species appeared to be associated only with P. juliflora, such as Acacia leucophloea, Bauhinia spp, Dichrostachys cinerea, Azadirachta indica, and Grewia tenax, which represent elements of the degraded formation of dry deciduous forests (Champion & Seth 1968).

Similarly in reserve forests, sites without P. juliflora had presence of Balanites aegyptiaca, Commiphora wightii, Capparis decidua, Gardenia resinifera, Delonix alata and Diospyros melano-xylon, recognized as dominant associates of the

SURESH & MATHUR 37

Table 1. Relative Importance Value (RIV) of some selected woody perennials on different habitats.

Protected Habitats Un-Protected Habitats

Forest Reserve Vidis Un-protected (Non- reserve Vidis

Open Grazing lands

Status of Invasion Invaded Un-invaded Invaded Un-invaded Invaded Un-invaded Invaded Un-invaded

Sites Sampled 3 3 1 3 1 6 10 10 Acacia senegal 4.9

(3-6.8) 37.5

(20.6-54.5) 52.5 69.86

(57.6-88) 9.9 21.92

(2-54.4) 5.92

(2.5-13.8) 20.36

(3.4-48) Maytenus emarginata

4.3 5.9 11.3 6.1 (5.4-6.8)

1.9 4.1 (2-7)

4.7 (2.9-7.2)

4.75 (3.5-6)

Ziziphus nummularia

7.5 (4.2-13.1)

1.7 2.8 6.45 (5.8-7.1)

12.3 16.86 (3.6-41.9)

16.8 (5.8-44)

39.8 (9.6-79.1

Euphorbia caducifolia

5.3 8.8 - 8.75 (6.2-11.3

- 9.6 (4.6-21.1)

14.5 (1.8-29.5)

9.2 (4.1-17.4)

Grewia tenax 2.8 3.4 - 4.0

10.1 4.35 (2.8-5.9)

9.56 (2.8-14.9)

7.5 (2.9-135)

Acacia leucophloea

4.3 4.75 (2.2-7.3)

- 4.2 (2.3-6.1)

2.3 - 3.9 27.9 (5.6-64.7)

Acacia nilotica 22.20 (18.1-26.4)

53.2 - - - 11.15 (3.9-13.1)

6.7 (4.6-10)

11.3 (5.5-17.7_

Cassia auriculata 16.8 (14.9-18.7)

23.1 (9-37.2)

- - 1.1 19.1 (4.7-28.5)

17 26.0 (11.2-41.8

Prosopis juliflora 6.7 (2.3-10.7)

- 2.8 - 1.4 - 15.2 (1.8-55.5)

-

Table 2. Diversity parameters of vegetation in different land uses in Jamnagar district Species richness.

With Prosopis juliflora Without Prosopis juliflora Land uses Mean Range Mean Range Forest 13.33 10-15 10.60 4-23 Reserve Vidis 10.8 10 11.00 3-11 Non-Reserve Vidis 16.8 16 8.40 3-12 Open grazing lands 8.20 4-14 6.20 3-10

Dominance concentration by Simpson index (λ) With Prosopis juliflora Without Prosopis juliflora

Land uses Mean Range Mean Range Forest 0.13 0.1-0.13 0.43 0.12-0.8 Reserve Vidis 0.3 0.3 0.39 0.34-0.41 Non-Reserve Vidis 0.1 0.1 0.25 0.11-0.34 Open grazing lands 0.24 0.07-0.59 0.31 0.15-0.47

Shannon Wiener Index H′ With Prosopis juliflora Without Prosopis juliflora

Land uses Mean Range Mean Range Forest 2.25 2.08-2.38 1.63 0.99-2.7 Reserve Vidis 1.67 1.67 1.30 1.01-1.62 Non-Reserve Vidis 2.42 2.42 1.67 0.84-1.67 Open grazing lands 1.68 0.74-2.5 1.39 0.88-2.05


climax formation. Further, species absent on all other sites and present only with P. juliflora were A. tortilis and Azadirachta indica. These two species are planted by the forest department on otherwise barren sites.

Open grazing land sites without P. juliflora supported A. senegal (mature trees and seedlings), (Table 1) Acacia jacquemontii, Butea monosperma, Cassia auriculata, and Phoenix dactylifera, all representing late successional stages, and all these species were absent on sites with P. juliflora. On the other hand, sites with P. juliflora had other species such as Suaeda fruticosa, a halophyte, as well as Salvadora oleoides and Sarcostemma acidum. It can be therefore said that on sites with P. juliflora, climax species and higher order seral species slowly deteriorate and disappear leaving behind only unpalatable, thorny species as associates of P. juliflora. In fact, presence of species of early successional status with P. juli-flora suggest that P. juliflora could either be causally related to these changes or that it could be responding to the same conditions as other early successional species it is associated with.

Impact on richness In sites without P. juliflora, average species

richness was maximum in reserve vidis (11) followed by forest (10.6), non-reserve vidis (8.4). (Table 2). Sites with P. juliflora showed the opposite trend: non-reserve vidis had maximum richness (16), followed by forests (13.33), and then reserve vidis (10). Open grazing lands had the lowest species richness in both cases, with and without P. juliflora. Species richness in protected areas having P. juliflora was not significantly different from areas without P. juliflora. But un-protected land uses, i.e., non-reserve vidis (Table 2) and open grazing lands had more species richness at sites with P. juliflora compared to those without it. This suggests that disturbance increases species richness (as reported by Brown & Archer 1999, and Archer 1989, 1995), but may also be respon-sible for the presence of P. juliflora.

This higher species richness on sites having P. juliflora was because of occurrence of species of early successional status and of lesser economic value such as Aerva jawanica, Bauhinia racemosa, Euphorbia caducifolia, Lantana camara, Mimosa hamata, Rhus mysoresis, and Lycium barbarum. Thus, more richness was due to increase in weedy and economically unimportant species.

Impact on diversity Simpson’s index in all the land uses when

invaded by P. juliflora was lower (Table 2). Higher Simpson’s index indicates the dominance of a few species, mostly of climax formation, as in the case of protected land use of forests and reserve vidi. In these habitats, invasion by P. juliflora caused sharing of dominance and consequently, Simpson’s index declined. Anthropogenic influences in open habitats enhanced entry of other weedy species. Consequently, non-reserve vidis and open grazing lands recorded much lower Simpson’s index than protected sites though whether this was due to the impact of P. juliflora invasion alone or the combined effect of P. juliflora and anthropogenic factors could not be estimated at this stage.

These trends were confirmed by Shannon’s index (Table 2). All sites having P. juliflora showed higher Shannon index than sites without it. Amongst sites of P. juliflora presence, non-reserve vidis had higher H′ (2.42) than reserve vidis (1.67) and forest had higher H′ (2.25) than open grazin-glands (1.68). These trends may have been due to the following reasons: non-reserve vidis had large-scale removal of grasses and were accessed by grazing animals who helped to disperse P. juliflora and other species, resulting in high H′. Following the same logic, open grazing lands with P. juliflora should have higher H′ than forest, but this is not the case. Open grazing lands have low H′ both with and without P. juliflora, presumably due to severe anthropogenic pressure.

Impact on endangered species Density of P. juliflora and C. wightii in open

grazing-land sites revealed that as the density of P. juliflora increased, that of C. wightii declined (Fig. 3). Though we have a limited dataset of only four sites, it does show a trend that with more of P. juliflora, C. wightii density declined making it vulnerable to local extinction.

Discussion

Open grazing lands invaded by P. juliflora and over utilized by humans and their livestock for over five decades showed community composition characterized by sub-climax and lower order successional species. Protected grazing lands invaded by P. juliflora did not show such a shift in species composition. The dominance was still of climax species. Commiphora wightii, an endan-

SURESH & MATHUR 39

Fig. 2. GIS Map of Grasslands in Jamnagar District.

Fig. 3. Density (number of plants ha-1) of Prosopis juliflora and Commiphora wightii at four represen-tative sites.

gered species, absent throughout open habitats, was still present in these protected sites. But entry of P. juliflora into protected grazing lands and forests was associated with a decline in succes-

sional status as exemplified by a reduction in dominance of the climax species A. senegal, Acacia nilotica, and M. emarginata (Table 1). Similar impacts of invasive plants on species richness, diversity, and composition of native species were also reported in the Czech Republic by Hejda et al. (2009). Since the above declining trends were observed in protected sites precluding any anthro-pogenic influence, this is perhaps the first field-based evidence of adverse impacts on community composition associated with P. juliflora (Ali & Awatif 2007)

Contrary to expectations, all habitats with P. juliflora had greater species richness, diversity, and lower dominance concentration than sites without P. juliflora (Table 2) despite its known adverse allelopathic impacts (Sundaramoorthy et al. 1995). Possible factors responsible include the facilitation effects of P. juliflora (e.g. P. juliflora leaf litter enriching the soil, its canopy providing shade or trapping wind born plant propagules). Open grazing lands with and without P. juliflora


had almost similar richness indicating that it is perhaps a function of disturbance rather than presence of P. juliflora alone that increased species richness. However, Sharma & Raghubanshi (2010) reported a decline in total species diversity and richness with increasing Lantana camara cover in Vindhyan’s dry deciduous forest. This variation is understandable as we are considering diversity of only woody perennials whereas Sharma & Raghubanshi (2010) considered all life forms, i.e., grasses, shrubs and trees. On the other hand protected sites with P. juliflora having more rich-ness may be due to localized site disturbance, which could enhance richness (Huston 1994).

At this stage, it is important to revisit biology and germination ecology of P. juliflora so as to understand, from the published literature and our own field observations, the causes of higher density and diversity of P. juliflora in disturbed and open grazing lands. Prosopis juliflora is a very hardy species, which can withstand drought, frost, fire, floods, extremes of temperature, and high wind velocity. Its shrubby nature allows it to regenerate from lateral meristems following die back of above-ground tissues (Bhimaya et al. 1967). Once germinated it also penetrates the soil quickly, growing roots faster than shoot (Gupta & Balara 1972). The root to shoot biomass ratio is often more than unity. These features enable its quick establishment. It also exerts high propagule pressure (Davies et al. 2000). Prosopis juliflora is known to produce large number of pods per plant (Muthana & Arora 1983). These pods are eaten by animals that disperse the seeds. Increasingly more animals eating these pods would result in more of its seedlings in the next rains. It is also ideally timed. Pods mature in March-April and are available for grazing during summer when other forage is scarce, and seeds in animal droppings are an ideal seed bank on the soil surface for germi-nation in the very first rains. Thus even in the persistently harsh arid environments, where possi-bility of invasion is ideally low, a singular event of rain can trigger invasion by P. juliflora. Such a role of benign interludes facilitating invasion of communities was also underlined by Rejmanek (1989) and D’Antonio (1993). Lonsdale (1999) listed disturbance regime as one of the major factors affecting invasibility of a species. In this study also, P. juliflora has been more invasive in disturbed and open grazing lands. In fact, cause of disturbance i.e., herbivory (by livestock), promotes its spread as discussed above

That introduction of grazing by livestock

increased its invasion into communities, as we report, also finds support from the work of Walker et al. (1981), Archer et al. (1988), Olff & Ritchie (1988) and Proulx & Mazumdar (1998). Diffe-rential increase in performance of invaders over that of natives during increased anthropogenic disturbance was also concluded by Daechler (2003) while evaluating 79 such studies. Disturbance and fluctuating environmental conditions, so common in these arid grazing lands, possibly make them more susceptible to invasion (Burke & Grime1996; Davies et al. 2000)

Increased alpha diversity in P. juliflora-dominated communities found in our study is due to preponderance of lower order successional species or ruderals. A similar trend was reported by Gordon (1998) who showed that increased representation of ruderals occurred as a process of homogenization exerted by highly invasive non-indigenous species. Similar findings were reported by Lonsdale (1999) and Tilman (1997).

Though Lambdon et al. (2008) agreed with the above view in general, higher local abundance of alien invasive species than native species was seen to impose greater ecological uniformity per unit area. Presumably, P. juliflora after invasion tends to impose uniformity of habitats at local levels though this needs longer-term experimental validation for final confirmation. Understanding mechanism underlying the impacts of exotic plant invasions has been emphasized by Hiremath & Agarwal (2010) and also in a recent review of 150 such studies by Levine et al. (2011) who concluded that invaders do have positive feedbacks through nitrogen cycling, fire regimes, and hydrology, when examined from an ecosystem perspective, and these may generate thresholds where impacts increase rapidly after critical invader “abundance.” Such species present the greatest threat to ecological systems. Viewed in this context, our studies are a pointer to the enhanced urgency and need for taking up in-depth studies to understand such feedbacks in the case of P. juliflora for identifying thresholds so as to better manage these invasive species and reduce damage to our ecosystem.

Acknowledgments

We are grateful to Director, CAZRI and Head, Division of NRE for providing necessary facilities for this work. The authors thank SAC, Ahemda-bad, and Ministry of Environment and Forest,

SURESH & MATHUR 41

Government of India, for financial support. We also appreciate the assistance of the staff of the Plant Ecology section, Shri V.K. Harsh, Abhay Singh, Late Teja Ram, and Bani Lal, who helped us in various ways. We profusely thank anony-mous learned reviewers for their valuable suggestions and painstaking efforts in improving this paper.

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(Received on 16.12.2009 and accepted after revisions, on 27.08.2012)

SURESH & MATHUR 43

Appendix Table 1a. Relative Importance value of woody perennials in reserve vidis in Jamnagar district.

Sites Invaded Un-invaded Species Modpar Pipartoda Khadjamebhaliya Jamvadi

Acacia ferrugenia 4.6 0.0 0.0 0.0 Acacia catechu 0.0 6.0 2.3 3.9 Acacia leucophloea 0.0 6.1 2.3 0.0 Acacia senegal 52.5 88.0 57.6 64.0 Acacia chundra 4.6 0.0 0.0 5.4 Butea monosperma 2.8 0.0 2.3 0.0 Capparis decidua 0.0 0.0 5.0 0.0 Commiphora wightii 0.0 0.0 4.7 0.0 Euphrbia caducifolia 0.0 0.0 6.2 11.3 Grewia tenax 0.0 0.0 0.0 4.0 Lantana camara 4.6 0.0 0.0 0.0 Maytenus emarginata 11.3 0.0 6.8 5.4 Mimosa hamata 5.3 0.0 0.0 0.0 Morinda tomentosa 0.0 0.0 4.7 0.0 Prosopis juliflora 2.8 0.0 0.0 0.0 Rhus mysorensis 8.8 0.0 0.0 0.0 Ziziphus nummularia 2.8 0.0 5.8 7.1 Ziziphus xylopyra 0.0 0.0 2.3 0.0

Appendix Table 1b. Relative Importance Value of woody perennials in non reserve vidis in Jamnagar district.

Sites Invaded Un-invaded Species Gumli Navi Pipal Morawli Banga Anandpar Positra Babarajar

Acacia ferrugenia 0.0 0.0 0.0 2.3 0.0 0.0 0.0 Acacia catechu 0.0 0.0 0.0 5.2 0.0 0.0 0.0 Acacia chundra 0.0 0.0 18.9 0.0 0.0 0.0 0.0 Acacia leucophloea 2.3 0.0 0.0 0.0 0.0 0.0 0.0 Acacia nilotica 0.0 8.0 19.6 3.9 0.0 13.1 0.0 Acacia senegal 9.9 0.0 31.1 10.1 12.0 2.0 54.4 Acacia tortilis 5.1 0.0 0.0 0.0 67.8 0.0 3.3 Azadirachta indica 4.2 0.0 0.0 0.0 0.0 0.0 0.0 Balanites aegyptiaca 0.0 9.4 0.0 0.0 0.0 0.0 0.0 Barleria acanthoides 0.0 0.0 0.0 0.0 0.0 12.6 0.0 Bauhinia racemosa 3.6 0.0 0.0 0.0 0.0 0.0 0.0 Butea monosperma 0.0 0.0 8.9 0.0 0.0 0.0 0.0 Calotropis procera 0.0 0.0 5.9 0.0 0.0 0.0 0.0 Capparis decidua 6.2 0.0 0.0 6.1 0.0 4.2 0.0 Cassia auriculata 1.1 24.0 0.0 28.5 0.0 0.0 4.7 Commiphora wightii 0.0 0.0 0.0 0.0 0.0 9.9 0.0 Cordia gharaf 0.0 0.0 0.0 5.2 0.0 8.8 0.0 Dichrostachys cinerea 8.9 0.0 0.0 0.0 0.0 0.0 0.0 Euphorbia caducifolia 0.0 7.1 5.9 9.3 0.0 4.6 21.1 Grewia spp. 5.8 0.0 0.0 0.0 0.0 0.0 0.0 Grewia tenax 10.1 5.9 0.0 2.8 0.0 0.0 0.0

Contd...


Appendix Table 1b. Continued.

Sites Invaded Un-invaded Species Gumli Navi Pipal Morawli Banga Anandpar Positra Babarajar

Lantana camara 0.0 0.0 0.0 0.0 0.0 6.3 0.0 Lycium barbarum 0.0 0.0 0.0 0.0 0.0 10.9 0.0 Maytenus emarginata 1.9 0.0 0.0 7.0 0.0 2.0 3.3 Mimosa hamata 24.1 0.0 0.0 4.7 0.0 22.2 0.0 Prosopis juliflora 1.4 0.0 0.0 0.0 0.0 0.0 0.0 Pupalia lappacea 0.0 3.6 0.0 0.0 0.0 0.0 0.0 Ziziphus spp. 1.9 0.0 0.0 0.0 0.0 0.0 0.0 Ziziphus nummularia 12.3 41.9 9.8 0.0 20.3 3.6 8.7 Ziziphus xylopyra 1.4 0.0 0.0 11.9 0.0 0.0 0.0

Appendix Table 1c. Relative Importance Value of woody perennials in forests in Jamnagar district.

Invaded Un-invaded Species

Ghumli Balambari Gadwadi Bhabarneshwar Khengarpar Kileshwar Acacia ferrugenia 0.0 0.0 0.0 0.0 0.0 1.2 Acacia catechu 0.0 0.0 0.0 0.0 7.3 0.0 Acacia chundra 5.3 0.0 2.0 0.0 0.0 2.9 Acacia leucophloea 4.3 0.0 0.0 0.0 7.3 2.2 Acacia nilotica 18.1 0.0 26.4 53.2 0.0 0.0 Acacia senegal 0.0 3.0 6.8 0.0 54.5 20.6 Acacia tortilis 0.0 24.9 7.2 0.0 0.0 1.7 Aerva jawanica 2.7 0.0 0.0 0.0 0.0 0.0 Ailanthus excelsa 0.0 12.6 0.0 0.0 0.0 0.0 Azadirachta indica 0.0 6.2 7.3 0.0 0.0 2.9 Balanites aegyptiaca 0.0 0.0 0.0 0.0 26.6 0.0 Bauhinia racemosa 4.3 0.0 0.0 0.0 0.0 1.2 Butea monosperma 2.7 0.0 2.0 0.0 0.0 0.0 Calotropis procera 0.0 0.0 0.0 0.0 0.0 0.0 Capparis decidua 0.0 0.0 0.0 3.4 4.4 0.0 Cassia auriculata 0.0 18.7 14.9 37.2 0.0 9.0 Cassine albens 0.0 1.2 0.0 0.0 0.0 0.0 Commiphora wightii 0.0 0.0 0.0 0.0 0.0 2.2 Delonix alata 0.0 5.1 0.0 0.0 0.0 3.2 Dichrostachys cinerea 0.0 0.0 0.0 0.0 0.0 6.7 Diospyros melanoxylon 0.0 0.0 0.0 0.0 0.0 1.2 Euphorbia caducifolia 5.3 0.0 0.0 0.0 0.0 8.8 Gardenia resinifera 0.0 0.0 0.0 0.0 0.0 1.2 Grewia tenax 2.8 0.0 0.0 0.0 0.0 3.4 Hyphaene indica 0.0 0.0 0.0 0.0 0.0 3.6 Ixora species 0.0 0.0 0.0 0.0 0.0 1.2 Jatropha curcas 0.0 6.0 9.6 0.0 0.0 0.0 Lantana camara 4.2 0.0 0.0 6.2 0.0 2.9

Contd...

SURESH & MATHUR 45

Appendix Table 1c. Continued.


Ghumli Balambari Gadwadi Bhabarneshwar Khengarpar Kileshwar Maytenus emarginata 4.3 0.0 0.0 0.0 0.0 5.9 Parkinsonia aculeata 0.0 5.2 0.0 0.0 0.0 0.0 Pithecellobium dulce 0.0 3.2 0.0 0.0 0.0 0.0 Prosopis cineraria 0.0 6.0 0.0 0.0 0.0 0.0 Prosopis juliflora 7.3 2.3 10.7 0.0 0.0 0.0 Wrightia tinctoria 19.4 0.0 0.0 0.0 0.0 0.0 Ziziphus nummularia 4.2 5.2 13.1 0.0 0.0 1.7 Ziziphus spp. 15.2 0.0 0.0 0.0 0.0 11.6 Ziziphus xylopyra 0.0 0.0 0.0 0.0 0.0 3.6


SURESH & MATHUR 47

Appendix Table 1e. Relative Importance Value of Woody Perennial in open grazing lands (Contd.) in Jamnagar district.


Gopi Bamansa Makanpura Beh Devalia Sankhala Bhangol Acacia senegal 0.0 0.0 0.0 0.0 0.0 20.2 0.0 Acaccia jacquemontii 0.0 0.0 0.0 0.0 0.0 4.7 0.0 Acacia nilotica 0.0 7.8 0.0 0.0 10.0 0.0 13.8 Bauhinia racemosa 0.0 4.3 0.0 0.0 0.0 0.0 0.0 Seddera latifolia 0.0 0.0 0.0 4.0 0.0 0.0 0.0 Butea monosperma 0.0 0.0 0.0 0.0 0.0 2.2 0.0 Capparis decidua 5.0 0.0 0.0 18.4 0.0 5.3 0.0 Cassia auriculata 0.0 0.0 0.0 0.0 0.0 17.5 41.8 Commiphora wightii 41.5 0.0 25.1 0.0 0.0 0.0 0.0 Euphorbia caducifolia 29.5 0.0 23.2 0.0 0.0 0.0 0.0 Grewia tenax 0.0 0.0 14.9 0.0 0.0 0.0 0.0 Heliotropium subulatum 0.0 0.0 4.9 0.0 0.0 0.0 0.0 Indigofera species 0.0 48.8 18.0 0.0 29.0 39.1 9.3 Maytenus emarginata 7.2 0.0 0.0 0.0 0.0 0.0 0.0 Phoenix dactylifera 0.0 0.0 0.0 0.0 0.0 0.0 4.0 Prosopis cineraria 0.0 7.8 0.0 0.0 0.0 0.0 0.0 Prosopis juliflora 6.5 24.2 9.4 4.2 55.5 0.0 0.0 Suaeda fruticosa 0.0 0.0 4.5 73.4 5.6 0.0 0.0 Ziziphus nummularia 10.5 7.2 0.0 0.0 0.0 10.9 31.1

Impact of invasion by Prosopis juliflora on plant communities

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