Floristic diversity and effect of anthropogenic activities on human-dominated grasslands in subtropical regions of Peninsular India

Indian subtropical grasslands are secondary habitats formed due to anthropogenic activities resulting in degradation of deciduous forests. Spread throughout Peninsular and Central India, they are important from economic and ecological points of view and are the prime source of fodder for the large population of livestock in this region. Pastures are either exposed to open grazing or protected and harvested periodically for fodder. In the present investigation floristic diversity of 21 sites from Western Ghats and Central India was studied, along with the effects of anthropogenic activities like burning and grazing on floristic composition in general and palatable species in particular. Over-grazing and burning were found to result in dominance of unpalatable species, making the grasslands less useful for livestock production. High rainfall and protection by local communities seem to play important roles in the dominance of palatable species in grasslands. Our results suggest that periodic harvesting and protection from burning and over-grazing should be encouraged and implemented in order to increase the potential of these grasslands for livestock production. Detailed studies are warranted to confirm these findings.


Introduction
Grasslands are productive biomes of the Earth, covering approximately 36% of terrestrial landscapes, similar to forest covers (Shantz 1954).Tropical grasslands of the Indian subcontinent are widespread, though they are not climax grasslands, being continuously exposed to anthropogenic pressures like lopping, shifting cultivation, burning and over-grazing (Dabadghao and Shankarnarayan 1973).Except for shola forests, which are the only natural communities, these grasslands are treated as secondary as they are formed as a result of human activities.Indian grasslands are important for their biodiversity values, cultural heritage and effects on the economy as a fodder source.
Pioneering work on ecology and biodiversity of Indian grasslands was done by Dabadghao and Shankarnarayan (1973).Various community aspects of grassland vegetation in India have been examined by a number of workers mostly focusing on species diversity, dominance and the www.tropicalgrasslands.info effects of anthropogenic pressures on grasslands from various parts of the subcontinent, such as Tarai region (Shukla 2009), Northeast India (Ramakrishnan and Ram 1988;Yadava 1990;Shankar et al. 1993), Northern India (Singh 1973;Misra and Misra 1981;Tripathi and Shukla 2007) and Western Ghats (Bharucha and Shankarnarayan 1958;Jose et al. 1994;Ramesh et al. 1997;Rawat et al. 2003).In spite of these efforts, the grassland communities of Peninsular India have largely been ignored by science, except for a few broad studies, e.g.classification of Indian grasslands (Oke 1972) and a few local studies like the synecological studies of grasslands of Marathwada University campus (Naik and Patunkar 1979).Oke (1972) classified Indian grasslands into 7 major habitat patterns and 24 minor sub-patterns based on various agro-climatic and habitat zones.The grasslands of Peninsular India are generally Dichanthium-Sehima type (Dabadghao and Shankarnarayan 1973) and occur along with other vegetation like evergreen forests, semi-evergreen forests, moist deciduous forests, dry deciduous forests, and thorny scrub forests, and along rocky outcrops (Puri 1960).These diverse and threatened habitats have received little attention when compared with other vegetation types like forests and cultivated landscapes.
In Peninsular India, many grassland patches are protected as community grasslands called 'Kuran' or 'gairan' and are used as large-scale fodder collection sites, where grasses and legumes are harvested.Many exclusively cattle-rearing nomadic communities like Gavali dhangar depend on these habitats (Gadgil and Malhotra 1982) and grasslands play, for example, a substantial role in total milk production in the State of Maharashtra.In addition, many grasslands serve as State Government wildlife sanctuaries for the conservation of endemic animal species like Black Buck (Antilope cervicapra), Chinkara (Gazella bennettii) and threatened bird species like Lesser Florican (Sypheotides indica) and Indian Bustard (Ardeotis nigriceps).
In the present work, the grasslands of humandominated landscapes of Maharashtra State were studied for their floristic diversity, uniqueness and effects of degradation due to burning and grazing on overall grassland diversity and fodder potential.This is the first attempt to understand the grassland communities of human-dominated landscapes in northern parts of .59°E) in recent times.

Materials and Methods
Twenty-one study sites (Figure 1) were selected from the list of grasslands of Maharashtra State catalogued in Dabadghao and Shankarnarayan (1973) and Oke (1972).Study sites fall into 2 major biogeographic zones of India, namely Central India and Western Ghats.Central India is characterized by low rainfall (annual mean 700-1,500 mm) and high temperature in summer (mean 45 °C), while the Western Ghats is one of the 35 biodiversity hotspots of the world (Myers et al. 2000) with abundant rainfall of 3,000-4,000 mm.Among the 21 sites, 3 locations are from Western Ghats (Vankusavade, Tikona and Talegaon) and the remainder from Central India.Study sites were shortlisted to cover spatial and environmental variations such as rainfall, latitude-longitude and protection status of the locality.Table 1 summarizes the spatial and climatic variables of the study sites.
Sites were surveyed in the post-monsoon months September and October, that is, the peak flowering time, during 2011-2014.Community enumeration was done using quadrats (2 x 2 m) laid in the areas of continuous grass growth using standard ecological techniques (Magurran 2004;Sutherland 2006).The number of quadrats per location was decided based on size and heterogeneity of the area.Number of quadrats per study site was determined by species area curve.A total of 67 quadrats were laid in these locations to document the grassland community.For tufted grasses, 1 tiller was recorded as 1 individual.Plants were grouped as very palatable (fodder) species, moderately palatable species, legumes and other herbs based on field observations, interviews with local stockowners and literature (Blatter and McCann 1935;Bor 1960;Patunkar 1980;Gorade and Datar 2014).Plant samples were collected and processed using standard herbarium methods (Jain and Rao 1977) and identified with the help of regional floras (Cooke 1901-08;Lakshminarasimhan 1996;Potdar et al. 2012).Identity of a species was confirmed by comparing it with authentic specimens deposited in the herbaria of Agharkar Research Institute, Pune (AHMA) and Botanical Survey of India, Western Regional Center, Pune (BSI).Specimens were deposited in AHMA.Data on the distribution, endemism and ecology of taxa encountered in this study are based on relevant literature (Lakshminarasimhan 1996).
Statistical analysis of the data was performed in PAST (Hammer et al. 2001).The diversity was determined by Shannon's index with the log base 2 calculated using PAST.Canonical correspondence analysis (CCA) was performed to understand the effects of spatial and environmental parameters on plant species of the grasslands.Environmental variables considered for statistical analyses included latitude-longitude, rainfall, maximum temperature, minimum temperature and variables indicating levels of grazing, burning, community protection and wildlife protection.Wildlife protection status was considered for areas which are protected and managed by the State Government, while community protection was considered for areas which are conserved and managed by local communities.Rankings were assigned for burning and grazing in the grasslands based on personal observations.www.tropicalgrasslands.info Cluster analysis was performed using PAST to understand the floristic uniqueness and similarities amongst the studied sites.Sample rarefaction (Colwell et al. 2004) was also conducted to understand whether the number of sites selected for the study was adequate or not.

Results
A total of 83 species belonging to 69 genera and 28 families was documented (Annex table).In addition to grasses and legumes, in high rainfall areas like Vankusavde, Tikona and Tadoba, growth of other herbs was also significant.The maximum number of species was found in Tadoba (S = 20) and the minimum number in Mhaswad and Nannaj (6 each).Grasslands like Atpadi, Yermala, Tuljapur and Mhaswad showed lowest diversity and tended to show the highest dominance of species belonging to the genus Aristida and of Heteropogon contortus.Tikona, which is located in a high rainfall region (4,000 mm), also recorded low diversity.Grasslands in Wadala, Shisamasa, Tadoba, Talegaon and Lamkani were characterized by high diversity and low dominance.Of these, Wadala, Shisamasa and Lamkani were communityprotected grasslands, while Tadoba was a governmentprotected area.Heteropogon contortus, Indigofera cordifolia and Aristida funiculata were the most common species, occurring in 16, 10 and 9 of the 21 assessed sites, respectively.Apart from the cosmopolitan taxa, these grasslands also harbor few endemic grass species like Ischaemum afrum, Sehima sulcatum and Lophopogon tridentatus.Lophopogon tridentatus, an indicator of exposed and degraded grassland, was observed at 5 sites with high dominance due to its unpalatable nature.Sehima sulcatum, a good fodder species and sensitive to disturbance, was recorded from 4 sites (Lamkani, Atpadi, Tuljapur and Nannaj), which are protected by government or local communities.Ischaemum travancorense, an endemic and threatened species, which was earlier distributed in Western Ghats, was found in Central Indian grasslands (Tadoba) for the first time.Ischaemum afrum, a perennial grass, is known to occur in agricultural landscapes and is recorded only in Shisamasa grassland, which is a mosaic of natural grasslands and agricultural fields.Apart from grasses, an endemic and threatened ground orchid, Habenaria longicorniculata, was observed in community-protected Vankusavade grassland (Western Ghats).
Sample rarefaction as per Colwell et al. ( 2004) suggests that 20 samples were adequate for the study as the curve reached asymptote and most of the diversity in the grassland patches was covered (Figure 2).Diversity indices (Shannon H) (Table 2) in all these 20 sites were compared and the range was 0.4 to 1.93 with highest H value in Talegaon and Shisamasa (H = 1.93) followed by Tadoba (H = 1.91).Talegaon, Shisamasa and Tadoba receive more precipitation than other sites (850-1,350 mm), which might have resulted in higher species diversity.The fact that Tadoba grassland is part of Tadoba Tiger Reserve and Shisamasa is community-protected could be another reason for higher diversity.On the other hand Tikona, though receiving higher rainfall (1,500 mm) than Tadoba, recorded the lowest diversity due to high dominance (D = 0.826) of Themeda triandra.Though  Tikona supports 10 species, 90% of the total individuals belong to T. triandra, which is characterized by profuse growth of tillers.Tikona recorded highest dominance of 0.825, followed by Atpadi (0.777) (dominated by Aristida sp.).Canonical correspondence analysis, performed to understand the effect of environmental variables on grass communities (Figure 3; Table 3), revealed that the first 2 axes explained a total of 81% of the variation among communities.

Floristic diversity
The grasslands were dominated by grasses and legumes, where Poaceae was the dominant family representing 27 (39%) species, while legumes were represented by 11 (15%) species.Grasslands with low diversity were frequently dominated by members of the genus Aristida and by Heteropogon contortus, which are dominant in grasslands frequently subjected to fire (Dabadghao and Shankarnarayan 1973).Tikona grassland in the high rainfall zone is dominated by the widespread grass species Themeda triandra, which is gregarious in growth and gives a characteristic appearance to hill slopes (Dabadghao and Shankarnarayan 1973).Themeda triandra is adapted to overcome competition from other grasses and herbs, especially during the seedling stage (Hagon 1977), which might be a reason for dominance of this species.Both community-protected and governmentprotected grasslands showed high diversity and low dominance.However, Talegaon, an unprotected grassland, possessed high diversity, mostly due to its geographical location that receives more rainfall (900 mm) than other sites (Table 1).
The current study highlights the presence of Ischaemum travancorense outside Western Ghats for the first time (Datar et al. 2014).This species was earlier thought to be endemic to Western Ghats and classified as a Least Concern species in the IUCN redlist (Rehel 2013).

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However, the scattered distribution and availability of this species in various habitats from coastal salty marsh to dry inlands suggests that taxonomic enumeration of this species needs further attention, as well as reassessment of its IUCN status.
The mosaic of natural grasslands and agricultural fields in Shisamasa supports Ischaemum afrum, which is the primary breeding habitat of the endangered bird Lesser Florican (Sypheotides indica).The grass patches amidst crops are preferred by this bird (Sankaran 1997).In Shisamasa, it lays eggs in the culms of Ischaemum afrum, thus making this grass important in the conservation program of the bird.Another taxon with conservation concerns encountered in this study was the ground orchid Habenaria longicorniculata, from Vankusavade grassland.This species is endemic to Peninsular India and is listed as Near Threatened in threat category (Kumar et al. 2000).Three sites were severely invaded by weedy species like Xanthium strumarium and Alternanthera sessilis (Singh and Karthikeyan 2000).These species must be eradicated from grasslands in order to control their further spread, thereby facilitating the conservation of grassland habitats.

Floristic uniqueness
When a dendrogram was drawn using Cluster analysis (Figure 4), floristic similarities amongst grasslands showed groupings based on the species assemblage and environmental parameters.Vankusavade is distinct from all other grasslands, as it is located in a high rainfall area in Western Ghats and characterized by dominance of the rainfall-associated taxon Eulalia trispicata, a typical member of the grass association of Western Ghats (Bharucha and Dave 1952).The bottom branch of the cluster groups, Waghapur, Supe and MPKV grasslands, is highly degraded by annual burning and over-grazing.In unprotected grasslands, over-grazing is responsible for dominance of non-palatable species over time (Naik and Patunkar 1979).One cluster contains Shisamasa, Wadala and Karanjasohol, i.e. sites from a high rainfall region (800-1,000 mm) displaying a combination of palatable and nonpalatable species.These 3 sites are under community or government protection, which prevents the grazingassociated plant community shift.Community-protected grasslands are characterized by strict bans on grazing and periodic harvesting of fodder during the post-monsoon (September-October), when the community gets enough fodder to overcome rainless summer months until the next monsoon (June-July).This periodic harvesting has advantages over direct grazing.By preventing the disturbance caused by cattle grazing, these grasslands provide higher yields of fodder.In grasslands, which are grazed regularly, the grasses are consumed by grazing cattle well before flowering.On the other hand in grasslands, which are not grazed and are periodically harvested, seed setting is achieved and seed is dispersed before harvesting, leading to regeneration of good quality fodder species during the monsoon in the next year.In contrast to communityprotected grasslands, government-protected grasslands are accessible to wild animals throughout the year and are not harvested by humans.Protection from domestic cattle helps them to maintain good grass growth and diversity.This practice, which is beneficial for improving productivity of grasslands, should be implemented in other openly grazed grasslands.
Cluster analysis has grouped sites like Phaltan-Atpadi, Laling-Lamkani and Bopdev ghat-Talegaon, which may be based on the close proximity of these sites.The maximum similarity between any 2 grassland patches was 55%, highlighting the need for conservation of each site.

Effects of physical parameters on diversity and fodder potential of grasslands
The CCA plot showed strong correlation between rainfall and moderately palatable grasses.Locations like Tadoba, Tikona and Vankusavade, which show high rainfall, are dominated by palatable grasses.Unpalatable grasses are more prolific in locations like Phaltan, Lamkani, Atpadi and Laling, which are located in low rainfall sites.High rainfall also showed positive correlation with growth of other herbs.In areas with less rainfall the sturdy grasses grow abundantly but higher rainfall gives herbaceous species other than grasses a chance to establish, which is evident in the CCA plot.Anthropogenic activities like burning and grazing showed strong association with the presence of legumes.Sites that are repeatedly burnt have soils with low or poor nitrogen levels that prevent the growth of most of the grass taxa, as fire is reported to reduce soil nutrients by burning the top layer and destroying humus (Pivello et al. 2010).However, legumes sprout and dominate in the early stages of succession due to their nitrogen-fixing root nodules (Towne and Knapp 1996).Grasses become dominant subsequently as they take advantage of the nitrogen availability in the soil.This phenomenon can be observed in locations like Mhaswad, Mograle ghat, MPKV, Yermala and Waghapur and is clearly depicted in the plot.
Good patterns were evident between community protection and highly palatable grasses.According to Dabadghao and Shankarnarayan (1973), protecting an Aristida-Heteropogon community produced a slow shift to Apluda mutica-Chrysopogon fulvus and Dichanthium pertusum, which are progressively replaced by Sehima nervosum and S. sulcata and ultimately by Themeda quadrivalvis.Presently, Lamkani, where Sehima is dominant, can be treated as the penultimate stage of this succession.Lamkani has been protected by local communities for the past 10 years, which has resulted in the community shift towards more palatable species.As sites like Wadala and Shisamasa are protected by local communities from burning and grazing and are not harvested before seed-set, the seeds of palatable species are dispersed and germinate in the next monsoon.In contrast to this situation, in over-grazed grasslands the palatable species are consumed by cattle much before they reach the reproductive stage, resulting in reduction in their population in subsequent years.Unpalatable fodder species on the other hand are not consumed by cattle and their chances of survival are much higher, thus making them dominant in the community.

Conclusion
Subtropical grasslands of India are situated in humandominated landscapes and are affected by livestock grazing and associated anthropocentric pressures on them.The present study covering 21 sites with varying levels of protection and utilization from Western Ghats and Central India indicated that grasslands protected by local communities with periodic harvesting show high growth of preferred palatable species.Most of the grasslands in this region are unprotected and/or over-grazed, hence the dominance of unpalatable species is evident.The majority of the livestock of the region depends exclusively on these degraded grasslands for fodder, so further degradation is unavoidable, and regaining of the original composition with species like Dichanthium-Sehima seems difficult with current management practices.However, protection and periodic harvesting of selected species can prevent further degradation.Future grassland management plans should consider and implement seasonal harvesting www.tropicalgrasslands.info practices.Seasonal harvesting should lead to better yield of fodder species even in protected areas and eventually decrease the dependence of domestic livestock on grasslands inside protected areas.However, a blanket management plan for the entire state would be difficult to implement due to highly varying rainfall and temperature patterns and magnitude of human disturbance across the state.Management plans for each site or group of sites in an ecoregion need to be developed with emphasis on wildlife conservation, as some of the grasslands also harbor highly threatened bird species.Protection of grasslands will not only provide fodder but also increase ground water level of the area by allowing rainwater to percolate into soil and avoid soil erosion during monsoon rains.The present study also documented invasion by many non-native weed species and future research work should focus on interaction of invasive species with native grass species and its implications for long-term conservation.Moreover, these fragile grasslands are present in the humandominated landscape and community participation in conservation is essential, so interaction of scientists and managers with local people will be vital if proper conservation and management are to be achieved.

Figure 3 .
Figure 3. Canonical correspondence analysis showing effects of environmental variables.(Axis 1 explains 56.2%, while Axis 2 explains 25.4% of the total variation of data.)

Table 1 .
Summary of study sites with geographic and environmental variables.Weather data were obtained from nearest weather observation station of the Indian Meteorological Department.

Table 2 .
Total taxa, dominance and diversity (Shannon index) of studied sites.

Table 3 .
Summary of Canonical correspondence analysis.