Analysis Vegetation Coverage Changes In Karst Area On RS And GIS

Vegetation coverage and it's changes is an important indicator of the regional ecological environment, have great significance in the hydrology, ecology, global change . Vegetation has a good function in ecological system of soil and water conservation, but also effectively influence hydrological process lagging flood peak, increased precipitation time to recharge groundwater and groundwater recharge. Development of good vegetation ecosystems, such as forest ecosystems, grassland ecosystems, shrub ecosystems can effectively prevent the erosion of heavy rain on the ground, slow-flow velocity, a time lag of surface runoff and reduce the intensity of floods function. At the same time, an increase of precipitation such as the infiltration of groundwater recharge and infiltration of the time, that is to increase effective recharge of the groundwater conservation played a very good role. At present, karst mountainous area southwest of soil erosion, desertification problems, in the final analysis on the changes in vegetation cover regional issues. The study of karst areas of vegetation for monitoring desertification and soil erosion is of great significance.In this paper, to the southwest area of a typical karst valley - in Longshan County in Hunan Luota this study, use remote sensing processing software ENVI4.3 who is the latest research on regional remote sensing images to correct geometry, terrain shadow of correction, atmospheric correction and a series of processing, extraction research the regional map vegetation coverage levels. Field survey verification vegetation coverage for accuracy. In ARC / INFO spatial analysis software module, with the support of regional integration on the Luota land-use types of data, the study area two vegetation cover images superimposed analysis, the final draw on regional changes in vegetation coverage.On the basis of the 1994 and 2006 average vegetation coverage statistics, analysis of the dynamic changes in the grading trends. Draw the following conclusions: From 1994 to 2006,Luota vegetation coverage in a stable upward trend. The study area of low vegetation coverage to the stability of the vegetation cover, vegetation cover in the high degree of development in high vegetation coverage area of the largest, and the vegetation coverage change is the smallest, can achieve more than 50 percent of the vegetation cover remain the same, that The level of vegetation to maintain regional stability trend of development. High vegetation coverage rate of more changes that high vegetation coverage of the region are large areas of damage, 62.29 percent more than in the area into high vegetation coverage, down to only a small amount of low vegetation coverage, show that the region be undermined Is not very serious. Luota vegetation types is the largest proportion of the two types of karst areas advantage shrub and grassland vegetation, respectively, accounting for 37.45 percent and 32.64 percent. From 1994 to 2006 the coming year, 10, shrubs, broad-leaved forest vegetation types of coverage with an average increase of the trend, shrub vegetation coverage increased by an average of 9.43 percent. Grass, coniferous forest vegetation types of vegetation coverage reduced, coniferous forest vegetation coverage rate of reduction to an average of -7.46 percent. Shrub vegetation coverage increased an average, mainly because the original vegetation cover in the lower shrub vegetation change to the succession of vegetation types of irrigation, has led to the shrub vegetation coverage increased. Grassland vegetation cover types of coverage an average of slightly less, mainly because it grassland vegetation types, part of the tree into a beheaded, alb der wood Youlin, resulting in an average of grassland vegetation types of vegetation coverage temporarily reduced, but long-term, to be Luota the entire region will increase the vegetation cover. Coniferous forest vegetation type of average coverage reduced, broad-leaved forest vegetation types of vegetation coverage increased long years in luota and can not be separated from the implementation of forest protection policy; Since the 1980s, luota implementation of vegetation protection policy, at the time was mainly planted Masson pine, China fir and other species, after decades of growth, China fir have become useful, in view of the protection of vegetation in the mountains of economic policy and a virtuous circle, to become useful Lin was newly planted young alternative, resulting in coniferous forest vegetation coverage declined from Vegetation coverage conversion matrix can also clearly see that since 1994 the high coniferous forest vegetation coverage for the change in the high vegetation coverage rate of more; Luota broad-leaved forest vegetation types, mainly due to the subsequent introduction of a number of economic forest, after Years of growth, enhance the entire region Luota the average broad-leaved forest vegetation coverage. Through the vegetation coverage on regional remote sensing estimates of the results of verification, the classification of vegetation coverage to 82 percent accuracy, to meet the basic ecological environment and climate change research the requirements for the karst area desertification and ecological environment monitoring technology to provide very good.