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Forest Resources
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Analysis of Fragmentation and Anthropogenic Disturbances in the Himalayan Forests: Use of Remote Sensing and GIS
The shape index among the various fragments ranged from 1.1 to 9.2. In general, it was observed that the smaller (in area) units had a low shape index than the larger units. For example, the smallest patches (having area < 1km2) had a shape index close to one (ideal shape being circular), i.e., 1.1 - 2.2, while the largest vegetation patches had a high shape index (7.7 - 9.2). A high shape index indicates micro-environment interaction at the edge of a vegetation patch. The edge interaction analysis, upto10 m inside from the edge of a patch, indicated that among the various size classes area affected by the edge impact ranged between 2.3% to 8.5% of the total area. In total 3793.86 ha area (3.3%) of the pine vegetation was found to be subjected to alterations in micro-environment due to exposed edges. Severity of edge impact was greater in the patches of smaller size class than the patches of larger size class; however, shape deviation from circularity was much more in the latter in comparison to the former. However, unaffected area from the edge impact accounted for 96.7% of the total pine vegetation. Statistics of the disturbance index model revealed that only about 228 km2 area on the entire landscape of the district was subject to no disturbance due to anthropogenic activities. At the district landscape 1299 km2 area can be categorized as being highly disturbed, 1077 km2 area as moderately disturbed, and ~560 km2 area had a low disturbance due to anthropogenic reasons. Forests of the Central Himalayan region have been subjected to exploitation throughout the history. Anthropogenically induced disturbances greatly impact the regeneration and status of forests (Upreti et. al., 1984). Anthropogenic disturbances are reflected in the decline of the tree stocking density, e.g., between 1973 and 1989 forests having good crown cover(>60%) declined annually at a rate of 27.8 ha shrinking to the total of 292 ha from 736.32 ha in a watershed of Gaula river (Rathore et al. 1997).
Table 3: Landscape attributes of pine forest fragments in district Almora.
Conclusion
Pine (Pinus roxburghii) showed extensive presence on the entire region of the district Almora due to various reasons which may vary from favourable climate, ecology (colonizer due to early successional nature of species), abiotic (landslides) to biotic (preference for this species by the state forest department for revenue generation). However, this species had a diffused presence throughout the landscape it was found to be more fragmentary in areas having high concentration of human settlements. RS & GIS based landscape approach is an emerging tool for identification and conservation of biological hot spots. This has been illustrated in the present study particularly in view of the fragmented nature of vegetation in the mountains and with reference to appropriate inclusion of human dimension in the management planning.
Acknowledgement
SS is thankful to Prof. B.L. Deekshatulu, Director, CSSTE-AP, India for providing opportunity. This work forms a part of the project carried out for M.Tech. Degree Course at CSSTE-AP, sponsored by ICIMOD, Kathmandu, Nepal.
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