Dynamic Analysis Of Desert Steppe Vegetation Based On Leaf Area Index In Siziwang Banner,Inner Mongolia

Leaf area index(LAI)is an important parameter to characterize leaf density and canopy structure.It plays an important role in global change,ecological environment assessment and surface process simulation.This paper used MODIS LAI data products to obtain the time series data set of the study area from 2000 to 2016,through a batch of reprojection,clipping,extracting DN value and other preprocessing.The analysis of temporal and space characteristics was performed by methods of mean method,difference method,differential method,coefficient of variation method,Slope trend analysis,Mann-Kendall trend test,partial correlation analysis,multiple correlation analysis and principal component analysis in the study area.It was found that the change trend of annual average LAI in the study area showed a ‘?' word shape in Chinese through the annual dynamic analysis,which showed a slow increase trend from February to April,and reached its maximum in August,at the same time the vegetation coverage was the highest.After September,the uniform speed declined,and began to slow down in November,and continued to decline in December and January,but the range was very small,at this time,there was barely vegetation coverage.In the interannual dynamic analysis,it was found that there were some fluctuations in LAI from 2000 to 2016,but there was a slight improve trend over whole study area.By calculating the Slope factor,it was found that LAI values have gradually increased from northeast to southwest in the past ten years.About 3/4 of the Slope values in the study area were greater than 0,and the result of M-K trend test was consistent with Slope's results,i.e.the overall trend was slightly improved.Which indicate that the grassland protection in the study area was better in the past ten years.Climate was the most obvious driving force for grassland.LAI was positively correlated with precipitation,but negatively correlated with temperature.Multivariate regression analysis shows that LAI was positively correlated with precipitation at P=0.01 level.Inner Mongolian grassland is an important natural resource in northern China.It is the basis of animal husbandry production in grassland area and the natural ecological barrier.Among them,the ecological environment of desert steppe zone is the most fragile,belonging to the transition zone between desert and grassland.Studying its multi-year change state can monitor the change and even movement of desert steppe zone in Inner Mongolia.It is also of great significance for rational development and protection of grassland resources in Inner Mongolia and effective development of its ecological barrier function in the future.