Vegetation Analysis with Reference to Topographic Variables using Remote Sensing Data (original) (raw)
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Tropical Ecology, Vol. 47 (1): 71-79 (ISSN: 0564-3295), 2006
The pattern of vegetation distribution on ground is always associated with particular topographic features. In order to understand the relationship between altitude, degree of slope and drainage network on one hand and the vegetation cover on other, topographical maps and Indian Remote Sensing satellite images (IRS-1A) on 1:50,000 scale were studied and IDRISI Geographical Information Software was used. The images were acquired in December 1989 and December 1990. This exercise demonstrated the control of elevation (altitude), relief and drainage on the spatial distribution of vegetation cover. The biotic factors are also responsible for the spatial distribution of vegetation. The vegetation of this area is mixed dry deciduous with few moist deciduous elements. The interpretation of satellite images resulted into five vegetation classes and GIS analysis indicates that the very dense forest was mostly confined to interfluve areas at variable relative relief, but particularly at higher elevation i.e. 400 and 800 m ASL. Open forests were found to be associated with settlements and agricultural fields. The sparse vegetation was common on interfluves and along nallas at high elevation. These results were strongly supported by ground surveys at selected locations.
Vegetation mapping is a primary requirement for various management and planning activities at the regional and global level. It has assumed greater importance in view of the shrinkage and degradation in forest cover. Usage of remotely sensed data for mapping provides a cost -effective method. In the pre- sent study vegetation cover assessment has been done using remotely sensed data in West Siang District of Arunachal Pradesh. Standard method was adopted for ground data collection by establishin g the correla- tion between satellite data and various vegetation types. Ground data were collected extensively and sufficient information was obtained. Vegetation class i- fication was performed using traditional methods of image recognition. The discrimination among the various forest types is restrained on satellite data o w- ing to the environmental set-up, intermixing of sp e- cies/vegetation and topography. However, to achieve higher accuracy, other methods have been considered. Hybrid...
seamless vegetation type map of India (scale 1: 50,000) prepared using medium-resolution IRS LISS-IIIimages is presented. The map was created using an on-screen visual interpretation technique and has anaccuracy of 90%, as assessed using 15,565 ground control points. India has hitherto been using potentialvegetation/forest type map prepared by Champion and Seth in 1968. We characterized and mappedfurther the vegetation type distribution in the country in terms of occurrence and distribution, areaoccupancy, percentage of protected area (PA) covered by each vegetation type, range of elevation, meanannual temperature and precipitation over the past 100 years. A remote sensing-amenable hierarchicalclassification scheme that accommodates natural and semi-natural systems was conceptualized, and thenatural vegetation was classified into forests, scrub/shrub lands and grasslands on the basis of extent ofvegetation cover. We discuss the distribution and potential utility of the vegetation type map in a broadrange of ecological, climatic and conservation applications from global, national and local perspectives.We used 15,565 ground control points to assess the accuracy of products available globally (i.e., GlobCover,Holdridge’s life zone map and potential natural vegetation (PNV) maps). Hence we recommend that themap prepared herein be used widely. This vegetation type map is the most comprehensive one developedfor India so far. It was prepared using 23.5 m seasonal satellite remote sensing data, field samples andinformation relating to the biogeography, climate and soil. The digital map is now available through aweb portal
Tropical Plant Research
Digital Elevation Model (DEM) has wide ranging application in the study and analysis of various environmental and biodiversity conservation issues. Due to geographical variations, the accuracy of DEMs generated from different satellite sources needs to be ascertained for choosing the best suitable DEM for a particular study area. In the present study, the performance of DEM datasets of Cartosat-1 and Shuttle Radar Topography Mission (SRTM) has been evaluated on the basis of slope, aspect, altitude and hill-shade map generated through these DEMs for different agro-climatic zones of Jharkhand. Elevation values deduced through Cartosat-1 and SRTM datasets were compared with actual Ground Control Points (GCP) recorded using Global Positioning System (GPS) for testing their accuracy. The forest cover map was created by Landsat 7 ETM+ data and subsequently superimposed on altitude map, generated using SRTM and Cartosat-1. Further, it was visually compared with the Survey of India topo-sheet (1:50000) for analyzing undulating topography and forest cover of Jharkhand. The comparative study based on different parameters for DEM dataset from Cartosat-1 and SRTM, reveals that SRTM data performed better than Cartosat-1 for the study of forest cover in different agro-climatic zones of Jharkhand.
Phytosociological Analysis in a Part of Western Himalayan Ecoregion Using Satellite Remote Sensing
The study was carried out in Kalsa watershed, Nainital district, Uttarakhand. Four different forest types viz., temperate broadleaf forest, temperate conifer forest, pine forest and degraded forest were mapped using satellite images of IRS-1D LISS III sensor. Temperate broadleaf forest was composed of different oak communities viz., Quercus leucotrichophora, Quercus floribunda, Quercus lanata besides Daphniphyllum himalense. Temperate conifer forest was dominated by Abies pindrow and was represented by only a single patch. Pine forest showed single species dominance of Pinus roxburghii. Degraded forest was composed of two different communities viz., degraded temperate broadleaf forest and degraded dry deciduous forest at higher and lower altitudes, respectively. Among all the oaks recorded in temperate broadleaf forest, Q. leucotrichophora was dominant followed by Q. floribunda and Q. lanata. Degraded forest showed minimum basal cover and density among all the forest types. Resource use pattern of different forest types was studied through dominance diversity curves. In comparative analysis of results with previous studies, loss of a patch of Quercus lanata community of temperate broadleaf forest has been recorded at one site. Present study concluded that there is an urgent need to regenerate and conserve the stands of Quercus lanata community and degraded forest.
The study was carried out in Kalsa watershed of Western Himalayan Ecoregion to quantify the landscape structure with special reference to different forest ecosystems. Vegetation and land use map generated using satellite remote sensing data was taken as an input for quantification of landscape structure, which was quantified based on different patch attributes (number, area, shape complexity) and landscape indices viz., Euclidean nearest neighbor distance and contagion. Temperate broadleaf forest exhibited high values for mean patch area, largest patch area, contagion and low values for number of patches, shape complexity and Euclidian nearest neighborhood in contrast to the degraded forest.
Mapping the Vegetation Types of Rajasthan, India Using Remote Sensing Data
Rajasthan, the largest state of India has a geographic area of 342,239 km 2 ; shows great variation in climate and vegetation. In the present study, vegetation types and land use of Rajasthan were mapped using multi-season IRS P6 LISS III data. Visual image interpretation technique was adopted in mapping the heterogeneity of land cover classes at 1:50,000 scale. Georeferenced phytosociological information was also used to delineate different vegetation formations. Altogether 26 vegetation type classes were mapped in the study region. The vegetation cover occupies 16.78% of the geographical area of the State. Of the total vegetation cover, forest area is contributing 4.71% of the geographical area. The main forest types of Rajasthan includes Dry Deciduous forest, Thorn forest, Broad leaved hill forest, Dhauk forest, Teak mixed forest and Riverine forest. The vegetation type map prepared provides a key input for biodiversity understanding at landscape level.