The Spatial Pattern Of Nitraria Tangutorum Populations In Oasis—desert Transition Zone Of Minqin Based On The Vector And Raster Data

The spatial pattern changes of Nitraria tangutorum populations reflect and react on the ecological environment.In this research,Nitraria tangutorum populations in the oasis-desert transition zone of Minqin was taken as the object.By field investigation,ArcGIS 10.2 and Google earth,we obtained vector and raster date about different age-class Nitraria tangutorum populations,basing on high resolution remote sensing data from Google earth.We compared the spatial pattern of different age-class Nitraria tangutorum populations,using a traditional point pattern analysis and an extending point pattern analysis,to find a more suitable spatial pattern analysis method adout vegetation in arid areas.Based on an extending point pattern analysis,We studied spatial pattern of different age-class Nitraria tangutorum populations in spatial and temporal variation,in order that reveal potential ecological mechanism in quality,and predict its development tendency.Draws following conclusions through the research paper:(1)Compared with Chang Lake study area,Nitraria tangutorum populations quantity in Qintu Lake declined gradually with the increased distances from sand.For maximizing the ecological function of ecological water conveyance and Nitraria tangutorum populations,we should plant Nitraria tangutorum populations in Qintu Lake in the above 200 m spatial scales from water.The age structure of Nitraria tangutorum populations in Qintu Lake presented in growing,mainly with younger individuals.Although the age structure of Nitraria tangutorum populations in Chang Lake also showed in growing,aged-class IV individuals number in A and C plots were larger.(2)The comparison about univarate and bivariate analysis of different age-class Nitraria tangutorum populations indicated significantly differences in partial scales,particularly the bivariate analysis.The bivariate analysis of different age-class Nitraria tangutorum populations,based on vector and raster data,brought to light that the results differed significantly at some small scales,and the bivariate analysis based on vector data was weaker than raster data at some scales,or the results was opposite among two approaches.Therefore,We found that the raster-based extending point pattern analysis was more reliable and effective about spatial pattern of vegetation in arid areas,if the size of the objects was differently,the scales of interest was the same order of magnitude as the size of the objects,and other objects competed for space.(3)The gradient changes about spatial distribution pattern of different age-class Nitraria tangutorum populations in 2002 and 2011 years,based on raster data,performed that aggregation was the important pattern type,and the aggregated degree gradually became weaker with increasing distances from sand.The temporal changes about spatial distribution pattern of different age-class Nitraria tangutorum populations in 2002 and 2011 years,based on raster data,found that I,II,III,V age-classes faced challenges,excepting for IV age-classes.The gradient changes about spatial association of different age-class Nitraria tangutorum populations in 2002 and 2011 years,based on raster data,showed that the negative association was significantly at small scales and slowly decreased with scale increase.The temporal changes about spatial association of different age-class Nitraria tangutorum populations in 2002 and 2011 years,based on raster data,revealed that individuals competition was more fierce,it showed the environment in oasis-desert transition zone of Minqin was developing reversely,under the natural condition.