Theses and Dissertations
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Item Investigating the roles of fire and cattle grazing on vegetation, invasives, and their implications on Bengal Florican (Houbaropsis bengalensis) breeding habitat use(Wildlife Institute of India, Dehradun, 2025) Thammaiah, Aadya; Nath, Anukul; Dutta, SutirthaGrasslands, though ecologically important, are often overlooked in conservation. These ecosystems are shaped by land-use practices such as fire and grazing, which can help maintain open habitats when appropriately applied. Mismanagement, however, can promote invasive species, threatening native biodiversity. The Bengal Florican (Houbaropsis bengalensis), a critically endangered grassland specialist, highlights the need for targeted conservation in such systems. This study assessed the combined effects of fire and grazing on grassland plant communities, including invasive plants, and Bengal Florican breeding habitat selection in Manas National Park. 2. For the vegetation survey, I selected study sites along gradients of fire frequency (based on 23 years of FIRMS data) and grazing intensity (using distance from human settlements as a proxy). At each site, I used circular plots to sample vegetation and assess species composition. To examine drivers of plant and invasive species abundance, I applied linear models (LMs), incorporating key covariates such as distance to forests, roads, and climate moisture index (CMI). I then used Indicator Species Analysis (ISA) to identify species associated with different fire-grazing regimes. I also performed a Linear Discriminant Analysis (LDA) to assess how well vegetation communities and structure could distinguish between different fire conditions. For Bengal Florican habitat assessment, I quantified vegetation structure visually and insect abundance using sweep netting in display and paired control sites. I used Binomial Generalised 8 Linear Models (GLMs) and Conditional Logistic Regression modelling to evaluate habitat selection by the species. 3. Tree and sapling densities peaked under intermediate fire, whereas shrubs and herbs had the highest density in low fire regimes. Saplings, shrub as well as grass cover peaked in low grazing regimes, but herb cover was highest in low grazing conditions. Among invasives, Leea asiatica and Chromolaena odorata were more frequent in intermediate fire, while Mikania micrantha and Ageratum conyzoides thrived under low fire. Grazing showed significant effects only on Mikania micrantha. ISA identified native species such as Dillenia pentagyna as indicators of low grazing and Cymbopogon flexuosus for medium and high fire regimes, among others. Bengal Florican selected sites with higher insect abundance, shorter vegetation (25–50 cm), with low (outside the PA) and high fire frequency (within the PA). 4. My results showed that plant communities showed species-specific responses to fire and grazing conditions. Bengal Florican habitat-use reflected a preference for open, short grasslands with high insect abundance. In conclusion, my study found that effective conservation requires tailored fire and grazing strategies that sustain open structure and control invasives, especially for the conservation of species such as the Bengal Florican.Item Nutrients and Metals in Soils and Vegetation of Araku, Andhra Pradesh, India(SACON, 2010) Chandra, Rachna; Azeez, P.A.Industrialization and urbanization in past few decades have caused tremendous ecological repercussions, which could be best seen in mining/extractive industry. India is endowed with a wide range of mineral wealth, and large scale mining activities are happening in various places in the country. Some important effects due to mining activities are the change in land use pattern and the associated changes in distribution of plants, animals, water bodies and soil system. Reclamation and reforestation of mined out areas have become necessary due to stern environmental laws in effect in the country, although exceptions are widely seen. The vegetation grown in mine sites is anticipated to accumulate or selectively exclude/tolerate high levels of toxic metals. Several of the soil characteristics can be playing important role in mobility of nutrients and metals in soil system. Thus, knowledge about these soil properties becomes obligatory as assessment of their distribution on a spatio-temporal scale would help better understand their likely mobility and bioavailability. The present investigation undertaken in three proposed mining locations at Araku, Andhra Pradesh, India during 2006 through 2008 is an attempt to examine the nutrients, alkali and alkaline earth metals, select heavy metals across the soil layers, and also alkali and alkaline earth metals, and select heavy metals in organs of select predominant plant species in the area. These species were primarily screened out on the basis of their ability so that they can be used during the initial stages of mine restoration programme, after the mining activities are ceased. As hyperaccumulators take up particularly high amounts of metals in their shoots, an attempt was made to assess the trace and heavy metal from view point of Transportation index (Ti = (metal concentration in leaf] / [metal concentration in root]) in various organs/compartments of the select plant species naturally occurring in the area.Item A study on the vegetation of shivaliks and outer himalaya in Dehradun dun district Uttar Pradesh(Wildlife Institute of India, Dehradun, 1996) Bhaisora, N.S.; Rawat, G.S.The subtropical zone or Bhabar tract in north India, characterized by fertile alluvial plains (Doons) and fragile Shivalik hills of Tertiary period, lies between the Upper Gangetic plains and outer Himalaya revealing the floral and faunal affinities with both the regions. Extensive cultivation, dense human population, industrial developments and livestock grazing in this area has caused fragmentation and degradation of forests. Of about 40,000 km2 only < 2000 km2 area has been brought under protected area (PA) coverage e.g., Rajaji and Corbett National Parks. The remaining forests continue to degrade. 2. Sal (Shorea robusta), a commercially "important tree, IS considered as climax species in this tract and has been studied extensively. However, there is a paucity of information on the overall conservation status and regeneration of forests in this area. Therefore present study was, undertaken with the following objectives: i) to study the structure and composition of the woody vegetation (tree and shrub layer) along the gradients of altitude and human use in Shivaliks and outer Himalaya, ii) to study the species diversity and human-animal use patterns in various zones, and iii) to assess and compare the regeneration status of Sal and associated tree species in the Shivaliks and outer Himalaya. 3. The study was conducted within about 500 km2 area in the lower parts of Debra Dun district, Uttar Pradesh (290 57' to 310 20' N lat and 770 35' to 190 20' E long). The study area also included parts of western Rajaji National Park, westerns Shivalik Forest Division, forests in Doon Valley, protected forest patches adjacent to Wildlife Institute of India (WII), Indian Military Academy (IMA) , Forest Research Institute (FRI), Upper parts of Rajpur, Malsi and mine reclamation sites near MussoorieItem A STUDY OF THE ECOLOGY OF SELECT SPECIES OF WEEDS IN DIFFERENT VEGETATION TYPES OF NILGIRI BIOSPHERE RESERVE(SACON, 2000) Mahajan, Maya VInvasion by weedy species of plants has serious impact on natural and managed ecosystems. Weedy species invade agricultural lands, fallow lands, roadsides, disturbed forests and plantations. Invasion by such species modifies the ecosystem structure and function. Invading species may dominate and displace the native vegetation and cause extinction of certain native species, leading to alteration in the original biodiversity of an area. In recent years, biological invasion is being recognized as a serious threat to biodiversity conservationItem Factors that Shape Vegetation in the Arid Zone of India(Wildlife Institute of India, Dehradun, 2019) Gayathri, S. Aaranya; Onial, Malvika; Page, Navendu V.In the current era of Anthropocene, it has become increasingly important to make predictions in plant-animal distributions as a function of the predicted changing conditions. Thus, the need to determine what shapes different vegetation structures are recognised, but, the results are often scale specific and rarely single factor determined. We investigate what causes a vegetation structure shift from a grassland to savanna and their possible intermediate transitions in the Thar Desert, North-Western Rajasthan, India. We sampled for vegetation in 67 one km2 grids spread across a 10,235 km2 study area capturing heterogeneity in precipitation. We analysed soil samples collected from sampled grids for soil texture, water holding capacity, total organic carbon, rodded and loose bulk densities. We collared three types of livestock (n=28) to determine potential grazing pressure in the sampled grids as one of the determinants. We used generalized linear models and non-metric multidimensional scaling to determine the determinants of vegetation structure and community. Our results show a clear scale dependence on how the determinants act– precipitation defines the larger community attributes such as species richness (R2=0.39, p= 1.029e-06); soil compaction under the precipitation umbrella defines the vegetation structure (and hence shift from grassland to savanna etc.) and grazing pressure (especially from the smaller livestock) defines the proportion of the life forms within each vegetation structure. The role of environmental determinants in determine vegetation shifts assures that the transitions are going to be gradual. This precludes the frequent finding of grasslands shifting to a shrubland or forest due to livestock grazing. This could be attributed to our finding of livestock having no forage preference to any particular species (χ2=25.76,df=18,p=0.1003) or life forms (χ2= 5.1939, df = 2, p = 0.0745) or possibly due to the low variation in livestock grazing in this landscape. We also found that change in the environmental determinants, however, can lead to two or three possible structure types. A predictive modelling shows the presence of mixed grassland, soft grassland, tree savanna, and tree shrub savanna in the study area. However, the map also indicates that 62.7% of it is already lost agriculture/settlement. Enclosures of Desert National Park protects only one vegetation structure type and covers less than 1%. We emphasize the urgent need to delineate conservation areas based on requirements of faunal species of interest and its habitat requirements before a complete wipe-out of vegetation structure types occur.