BIODIVERSITY CHARACTERISATION USING IRS DATA

Introduction

Biodiversity is the totality of genetic, species, ecosystem and habitat diversity in a region. They have evolved through millions of years of evolutionary history. India is identified as one of the important biodiversity pool, known for their genetic, ecological and economic prudence.India is also among first three countries supporting endemic species. In the last four decades attempts have been made to identify hot-spots and unique habitats to preserve, protect and propagate through in situ and or ex situ measures.

Remotely sensed data have been used to study landcover, vegetation types, physiography/ landforms and human interventions at fine to coarse spatial scales. Such information provides better knowledge on potential, extension, composition, evolution and rate of transformation of habitats and ecosystem. Recent approaches to study forest ecosystem emphasize on spatial characterization and vertical analysis together using landscape ecological principles. Landscape is comprised of several landscape elements which appear as patches and varsy markedly in size, shape, type, heterogeneity and boundary characteristics. Each of the above characteristics has its own significance in ecosystem structure and function.

Satellite remote sensing based approach has been developed to analyze ecosystem using landscape ecological principles in two protected areas viz., Madhav National Park ( M.P. ) and Balphakram National Park ( Meghalaya).

Madhav National Park

The satellite remote sensing data has been used to prepare vegetation type and physiography maps. These maps were taken to Geographic Information System (GIS) through the process of digitization. The homogenous vegetation strata (derived by combining vegetation and physiography maps) were randomly sampled on ground. Basic data on biomass, species richness, stand productivity and other related community parameters were assigned as attribute information in GIS. The spatial and nonspatial data base has been analyzed in GIS for patch characterization in three management zones

The patch parameters (size, porosity, patchiness and shape) indicate that the central zone (least disturbed) is distinctly different from other two zone's where disturbance is quite high. The patch size and porosity have been found to be most important parameters to discriminate differences in the ecological status of the three different management zones of Madhav National Park. The patchiness and shape also provide supportive information. The vertical community analysis has shown that the dommunities differ significantly in diversity indices. The most significant observation of the present study was the reduction in species diversity with the increase in disturbance.

Balphakram National Park

Balphakram is locally known in Garo as an area where wind blows continuously. Climatically the area experiences typical tropical climate. The diverse ecological conditions prevailing in the area support typical vegetation with varied plant life forms. The inaccessibility of the area has preserved the forests comparatively undisturbed to certain extent. The area has been originally covered by tropical moist evergreen forest as the climatic climax formation.

The vegetation type has changed to second formations as a result of human intervention primarily due to shifting cultivation. The natural and secondary forests have gradually developed distinct forest types. The patch characteristics of the Balphkram National Park landscape has been evaluated 0.5xO.5 km (17xl7 mask, pixel size = 30 While a moving grid was used for the measurement of interspersion and juxtaposition; the patchiness and porosity has been measured using a fix grid. A buffer zone of 2 km around the park has been compared with the landscape elements core region of the park. These parameters were calculated for the core and buffer regions of the national park.

Results and Discussion

Analysis of interspersion image of the study area indicates that the core of the park shows homogeneity and prominently dominated by tropical moist evergreen forest followed by the secondary formations. However, secondary formations have less degree of homogeneity. The buffer zone shows higher frequency of interspersion values indicating heterogeneity of the landscape in general. This heterogeneity of the landscape is primarily due to human interventions mainly due to shifting cultivation. Analysis of patchiness shows that in core region overall patch density is low in comparison to the buffer zone. Patchiness value is high particularly in north west and south west region of the park. Porosity of the tropical moist evergreen forest which is the natural forest type in the core region is more as compared to the buffer zone. This is primarily because of the physiography of the area as the area is inaccessible and the human influence is very less. Since the porosity is high and the landscape is more homogeneous conclusively less fragmented as compared to the buffer zone.

Conclusion The above two studies indicate that the patch boundaries defined using interpretation of the satellite remote sensing data were useful to analyse spatial pattern of landscape mosaic. The effects of management (static or temporal) can be monitored using this method. The aspects which can be monitored are landscape structure, community parameters and biodiversity distribution as a function of disturbance gradient.