Theses and Dissertations

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Author: search.filters.author.Rawat, G.S.Subject: search.filters.subject.Sikkim

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    Assessing the Impacts of Livestock-Induced Disturbance on the Vegetation Composition and Forest Regeneration of Sikkim's Mid-Elevation Forests
    (Wildlife Institute of India, Dehradun, 2019) Luxom, Nisam Mang; Rawat, G.S.; Sathyakumar, S.
    1. Livestock rearing earlier contributed sizeably to Sikkim’s economy, thus putting immense pressure on natural forests, which were converted into artificial pastures. These forests have not been subjected to evolutionary grazing pressure and differ in their sensitivity to the effects of livestock grazing, as compared to the historically-grazed tropical grasslands and rangelands. 2. This study aims to assess the impacts of livestock-induced disturbance on the vegetation and forest regeneration of the Sikkim Himalayan mid-elevation forests. 3. We sampled vegetation in and around pastures under different levels of livestock grazing pressure - from currently grazed to abandoned; and from heavily grazed to lightly grazed. 4. We found highest species richness and diversity values in abandoned pastures, as compared to areas which are currently grazed as well as areas which have not had a historical pasture presence. We found highest species richness and diversity values in abandoned pastures, as compared to areas which are currently grazed as well as areas which have not had a historical pasture presence. 5. We found significant difference between plant species composition among various livestock grazing levels. Species composition differed due to (1) grazing-tolerant herbaceous species, and (2) encroaching shrub or bamboo at the pasture boundaries in the absence of livestock as a control. 6. Seedling densities were overall lower in actively grazed pastures than in abandoned pastures. Seedling densities for buffer forested areas of the different livestock grazing levels were comparable, apart from the lightly grazed treatment, which had very low seedling densities. Sapling densities was higher in and around lightly grazed pastures, than the other livestock grazing levels; this contradicts the trend seen in seedling densities. 7. Seedlings and saplings in lightly grazed areas were from the same species pool; we propose that the decrease in the former and the increase in the latter’s densities is due to successful recruitment of the seedlings to the sapling stage. 8. Livestock grazing level, slope, shrub volume and position of plot (either within the pasture area or in the buffer forested area) explained seedling density. Seedling densities were highest in abandoned pastures, low in areas with high slope values, low in areas with high shrub volume and higher in buffer forested areas, compared to pastures. 9. Livestock grazing levels, slope value, shrub volume and position of sapling (wither in buffer forested areas or pasture areas) influenced sapling densities 10. Areas with and without active livestock grazing had similar proportions of unpalatable – palatable species; suggesting that direct herbivory may not be an important regulation by which density of regenerating is affected. Instead, other indirect livestock-related impacts, such as trampling or dung deposition, could lead to changes in regeneration metrics. 11. Successful regeneration occurs across the different livestock grazing levels, however the composition of regenerating species differs. Restoration of disturbed forests by artificial regeneration may not be required, as it may interfere with natural successional dynamics already in motion.
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    Habitat use and food selection by wild and domestic ungulates in the Sikkim Transhimalaya.
    (Wildlife Institute of India, Dehradun, 2007) Chanchani, Pranav; Rawat, G.S.
    By defining a resource, determining the resources available to animals and sampling the array of resources actually used by an animal (Krebs 1999), it becomes possible to gauge the nature of interactions between species. This study explored aspects of resource use by diverse assemblage of wild and domestic herbivores including The Tibetan argali (Ovis ammon hodgsoni), Tibetan Gazelle (Procapra picticaudata), kiang (Equus kiang), blue sheep (Pseudois nayaur), domestic yak and sheep in a Trans-Himalayan environment during the lean winter period. Sampling was carried out in a systematic manner using trails, as well as by sampling opportunistically. To quantify vegetation, a 3.52 Ian grid was overlaid on an image of the study area, and grids were randomly picked from these for random sampling. A number of habitat and vegetation variables were measured or noted for all ungulate sightings or within vegetation sampling stations and these were used in analysis to ascertain patterns of habitat use and food selection. U sing a hierarchy of spatial scales, the study modeled animal distributions, and investigated the use of habitats and food habits of ungulates in relation to the availability of these resources in their environment. The study's major findings were that all ungulates were found to occur in the true Trans-Himalaya except for the blue sheep which selected more mountainous terrain in the transition zone between the greater and Trans-Himalaya .. Statistical tests of significance revealed that ungulates differed from one another or from random in their use of resources. Further, terrain features appeared to influence habitat selection to a greater-extent than vegetation. Finally, the findings of this research indicate that although the wild and domestic ungulates of this region all exist in relatively large numbers, they tend to vary in their use of habitats and food either by differences in their distribution, or in the selection of finer environmental (habitat and food) variables. The study therefore concludes that competitive inter-specific interactions are not very apparent in this region.