Spatial-temporal Change Of Vegetation In The Western Songliao Plain Based On NDVI And RUE

Vegetation is the most critical component of terrestrial ecosystems. It is also themost active element in this system. The west of Songliao Plain is the east fringe ofagro-pasture transitional zone in northern China and highly sensitive to global change.Monitoring and analyzing the dynamics of vegetation cover changes in this semi-aridregion not only reveals the characteristics of ecological environment changes, but alsohelps to assess the effects of the large-scale ecological restoration projects over thepast ten years. It will provide essential data and scientific basis for ecologicalenvironmental protection and the coordinated development of social economy.In this paper, multi-temporal series of satellite SPOT-VEGETATION normalizeddifference vegetation index (NDVI) images and precipitation data from1999to2011were used for estimating rain-use efficiency (RUE) of vegetation. Thespatial-temporal changes of vegetation based on cumulative NDVI and RUE duringgrowth season (from April to October) in the western Songliao Plain wereinvestigated using the temporal variation trend model and the impact factor analysismodel with remote sensing and GIS. The relationship between vegetation change,climatic and anthropogenic factors were explored.Main research results are as follows:1. From1999to2011, the vegetation cover in the west of Songliao Plain tended toimprove. The increase in cumulative NDVI was greater than RUE, indicating thatthe ecological engineering project in the study area during the last13years hadsome positive effects.2. Changes in climate likely function as one of major controllers for interannualvariations in vegetation activity. Overall, the cumulative NDVI、RUE relatednegetatively with meteorological factors. Precipitation and relative humidity hadpositive correlation with cumulative NDVI, while negative correlation with RUE.The temperature and sunshine duration had negative correlation with cumulativeNDVI, and positive correlation with RUE. There existed obvious spatialdifferences between meteorological factor and vegetation change.3. The socio-economic factors had certain impact on vegetation change. On thewhole, socio-economic factors had positive correlations with cumulative NDVIand RUE. However, between livestock, grain output and RUE, the positive andnegative spatial correlation were half and half. 4. The grey relational analysis demonstrates that spatial and temporal differences inthe main factor caused vegetation changes in the study area were found. As awhole, changes in vegetation coverage and productivity were mainly affected byaverage temperature, average humidity, cumulative sunshine time and populationdensity.