Population Changes Of Achnatherum Splendens In Lake Hulun And Its Response To Climate Changes Based On Remote Sensing During 2000 To 2015

Achnatherum splendens population is one of the typically non-zonal vegetation occurred in arid and semi-arid regions.It plays important roles in maintaining species diversity,soil and water conservation and promoting regional livestock production.However,with the warming climate intensified,the habitat of Achnatherum splendens in the mid-latitude area changed,and its population distribution and also the characteristics of quantity and quality changed.Therefore,the quantization of area and quantity of Achnatherum splendens population,and the analysis of topographic factors and climatic factors of affecting its habitat,it can not only understand the status of the local Achnatherum population guiding the ecological protection and animal husbandry development,but also provide help on the research of vegetation development in arid and semi-arid areas in the context of global warming.In this paper,a series of Landsat satellite remote sensing data from 2000 to 2015 were used to extract the Achnatherum splendens population in the Hulun Lake area through the decision tree classification method and the pixel level monitoring method.The spatial and temporal changes of the area and spatial pattern were analyzed.Based on the topography data of the study area,combining statistical analysis and hydrological analysis of GIS,the distribution characteristics of Achnatherum splendens population in Hulun Lake area were explored.On this basis,the climatic indexes in local meteorological stations such as temperature,precipitation and humidity were used in the past 16 years to analyze the changes of Achnatherum splendens population and the response characteristics to climate factors.Research indicates:?1?In the year 2000,2005,2010 and 2015,the area of Achnatherum splendens was103.97km²,141.42km²,173.28km²,201.95km² respectively,and the corresponding patch number is 6066,11853,19632,22762.In 16 years,the area of Achnatherum splendens population in Hulun Lake increased significantly,the total area increased by 97.98km²,and the number of patches increased by 16696.The number of small communities with area less than 5000m² was the fastest and the larger population with area greater than 1km² has a slow growth.?2?By analyzing the main distribution of typical grassland of Stipa and the Achnatherum splendens population vegetation quality in Hulun Lake,we have discovered that the NDVI and RVI vegetation indices of Achnatherum splendens were significantly higher than those of typical grassland,and the spectral features were mainly concentrated near the NDVI value 0.29,near the RVI value 1.82,which has demonstrated that the Achnatherum splendens population has high production capacity.?3?On the analysis of research area of distribution of Achnatherum splendens population slope in 2015,we can discover that the distribution of Achnatherum splendens population increased rapidly with the increase of slope,and then decreased rapidly;on the flat surface with less than 1 degree,the distribution of Achnatherum splendens population was low;more than 90%grew in the slope of more than 1degree and less than 5 degrees of the bottom of the slope,slope foot area,and more than 10 degrees above the steep area is basically no Achnatherum population distribution;in light of the orientation of slope,more than 70%of the Achnatherum splendens population distributed in the sunny slope.?4?According to the analysis of the meteorological station data in the study area,we can find out during the period from 2000 to 2015,the Achnatherum splendens population of this region flourished in July,August and Annual accumulated temperature higher than 10,the average temperature increased unsteadily and slowly.The annual precipitation increased slightly,while the amount of evapotranspiration increased dramatically so that the amount of water loss increased and the average humidity decreased.The results showed that there was a positive correlation with the change of water loss and temperature.The results showed that the change of Achnatherum splendens population in 16 years was positively related to the meteorological factors.With the rise of average temperature and the reduce of average humidity,splendens population area increased.There is reasonable concordance between the climate change and the biological characteristics of splendens population,such as strong root,drought,salinity,adapted to clay and sandy loam.