Impacts Of Vegetation Landscape Structure Change In Loess Plateau Based On Multi-scale Analysis

Loess Plateau was affected by human activities for a long time, most of thenatural vegetation replaced by artificial vegetation. Spatial change of vegetationlandscape structure in Loess Plateau was complex and diverse. It has an importantpractical significance to reveal the evolution and change about the regionalenvironment the dynamic monitoring of the Loess Plateau vegetation landscapestructure and in-depth study of the relationship between vegetation and topography,climate and human activities。We use landscape ecology theory and methods, and combined with remotesensing (RS) and geographic information system (GIS) technology in this paper. thetwo main metheods like as. vegetation type data and vegetation index data of differentperiods and pixels were used to study the change of multi-scale Landscape structurein Loess Plateau based on the metheods of Fragstats Landscape index and waveletanalysis. At the same time, we analysis the vegetation landscape structure changeleading from both natural and anthropogenic factors in Loess Plateau.The results show that:(1) There was a step change for vegetation landscape from1982to2011in Loess Plateau. According to the fluctuated of the growing season(4-10) normalized vegetation index (GIMMS NDVI and MODIS NDVI) in LoessPlateau, we found that vegetation cover overall is getting better and better, but it had avolatility change throughout the study period:vegetation recovery phase(1982-1990a), the most significant area for vegetationrestoration such as: Hetao Plain of southeast, northern of Shaanxi and Shanxi, andnorth-central of Gansu. vegetation degradation stage from1990to2001, the easternpart of the Ordos Plateau, central regions of Shanxi and Shaanxi were the mostserious area for vegetation degradation. The second vegetation recovery stage is from2001to2011. north-central of Shaanxi and Shanxi, central and eastern regions ofGansu were the typical areas. Yan River Watershed have a big change for vegetationlandscape, so seem the watershed as typical vegetation change area, madepreparations for the small-scale study on the vegetation landscape structure changes.(2) whether the entire Loess Plateau or Yan River watershed of typical vegetationchange area in Loess Plateau, vegetation landscape matrix is always grasslands and crops, coniferous forest and broadleaf forest, and other type such as landscape desert,construction land and waters were mosaic in them. From the time point of view, thedegree of fragmentation of the vegetation landscape gradually deepened and deepenedfaster after2000, the most typical vegetation types such as: shrub, grassland and crop.On different spatial scales, the degree of fragmentation with the increase of the scalegradually decreases, and when the spatial scale increases to a certain extent, itschange over time gradually be masked. Aggregation and separation over time did notchange significantly, higher degree of aggregation in a small scale, especially smallerplaque like as coniferous forest, residential areas and waters. With the increasing ofthe scale, the degree of aggregation is reduced, while separation gradually increased.the most representative vegetation were coniferous forest, shrub and grassland. Theelements’ abundance and dominance of the Vegetation landscape are not sensitive tothe size of the particle size of the space, but influenced by the spatial extent, showed adifferent variation between the small-scale and large or medium-sized scale. Thecomplexity of the patch shape was first decreased and then increased with the increaseof the landscape scale trends, such as the prairie. Vegetation landscape was tend todiversification in general. If there was a certain size of the study area or a certainextent, with increasing of space particle size, the landscape diversity slightlydecreased, while with the increasing of the size of amplitude and the particle, thediversity will gradually increase.(3) The spatial heterogeneity of NDVI is mainlyreflected in scales of480m、960m、1920m、3840m、16km、32km、64km and128km.The heterogeneity of vegetation landscape was related to the data acquisition time,data resolution and spatial location. The higher of the Vegetation index and theresolution of the data, the greater of spatial heterogeneity for vegetation landscape.Also, the fragmentation degree of landscape vegetation and NDVI spatial differencealong the longitude were greater than latitude.