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Banaras Hindu University (2017)

Ecological analysis of the impact of land use change on microbial community composition in dry tropics

Kumar,Chandra Mohan

Titre : Ecological analysis of the impact of land use change on microbial community composition in dry tropics

Auteur : Kumar,Chandra Mohan

Université de soutenance : Banaras Hindu University

Grade : Doctor of Philosophy (PhD) in Botany 2017

Résumé partiel
1. Land-use change (LUC) and excessive resource extraction resulted in 0.6% loss of forest cover per year worldwide. Restoration of forests poses a major challenge globally and especially in the tropics as these are more vulnerable to LUC. Soil microbial community responds more readily to soil disturbances in any ecosystem, relative to chemical or physical soil properties. Any change in microbial community composition, could be used as the sensitive index of soil disturbance. Several studies have shown LUC to have significant impact on microbial community especially in the temperate regions. The way, as to how LUC affects the community composition in terms of disturbance and ecosystem restoration in dry tropics, has to be worked out.
2. Elucidation of microbial community using Phospholipid fatty acid (PLFA) analysis provides direct information on the identification, classification and quantification of microbial community composition. Since bacteria and fungi constitute the significant group of soil microbial community, any change in their dominance, as represented by fungal : bacterial (F/B) ratio, affects the major ecosystem structure and function.
3. The broad objective of the present study was to evaluate the impact of land-use change from natural forest (NF) to degraded forest (DF), and then to either Jatropha plantation (JP) or the agroecosystem (AG) in the dry tropics on soil microbial community composition in terms of PLFA biomarkers and microbial biomass C and N, soil organic C and N and other physicochemical properties.
4. This study was conducted for two annual cycles in four land-use types involving NF, DF, AG, and JP. Among the four studied site, three sites DF, AG, and JP were situated at Rajeev Gandhi South Campus, Banaras Hindu University, Barakachha, and the fourth i.e. NF was situated at the Marihan range, approximately 7-8 km from Barakachha, at Mirzapur, Utter Pradesh, India.
5. The climate is dry tropical monsoonic having distinct seasonal variability. Soils of the study site were residual ultisol, sandy to sandy loam in texture and reddish to reddish-brown in colour.
6. For the sampling, each site was first divided into three contiguous study sites and each study site was divided randomly into nine sub-sites in NF, DF and JP whereas eight in AG. Five subsites were selected randomly out of the nine sub-sites at a time. Two soil samples were collected from each sub-site, (i.e. total of 10 soil samples from each study site) with the help of soil corer (diameter 4 cm and height 10 cm, and mixed together to represent a single composite sample of a study site. Soil sampling was done from all the four land-use types at three soil depth i.e. 0-10 cm, 10-20 cm and 20-30 cm during rainy, winter and summer season

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