降水量和温度对植被覆盖指数影响的空间非平稳性特征——以新疆伊犁河谷地区为例

多变量空间相关分析多基于时间序列数据,对数据时长与统计要求严格,空间非平稳性特征分析可以利用单期数据分析多变量之间的相关性。通过空间变系数回归模型分析了2006年和2011年的新疆伊犁地区降水量和温度对植被覆盖度指数影响的空间变化特征,利用局部线性地理加权回归(GWR)方法估计得到了回归系数曲面,揭示出变量间相互影响的空间异质性,同时利用线性回归最小二乘估计进行了对比。结果表明:(1)空间变系数回归模型可以用于变量间的空间相关分析;(2)局部线性GWR估计方法明显优于线性回归最小二乘估计;(3)拟合结果表明,伊犁地区降水量和温度对植被覆盖指数的影响具有显著的空间非平稳性特征;(4)模型估计误差是降水、气温之外的地形、地貌及人类活动等多种因素造成的,需进一步研究。方法可为具有空间非平稳性特征变量间空间相关性分析以及植被覆盖指数的空间模拟分布提供思路和方法。

Spatial non-stationarity characteristics of the impacts of precipitation and temperature on vegetation coverage index: a case study in Yili River Valley, Xinjiang

The multivariable spatial correlation analysis is mainly based on time series data and requires long-term time series for statistical analysis. The analysis of spatial non-stationary characteristics can determine the relationship between multivariate variables by using single a single dataset. Based on the spatially varying coefficient regression model, this study analyzed the spatial variation characteristics of the vegetation coverage index in response to precipitation and temperature in the Yili area of Xinjiang in 2006 and 2011. The regression coefficient map estimated by using the local linear geographical weighted regression(GWR) method further revealed that the spatial heterogeneity of the interaction between the variables. The results were compared against linear least squares regression method. The main findings are the following: (1)The spatially varying coefficient regression model can be used to analyze the spatial correlation between variables. (2) The local linear GWR is superior to the linear least squares regression method. (3) Results showed a clearly spatial non-stationary characteristics of the vegetation coverage index under the effects of precipitation and temperature in the Yili area of Xinjiang. (4) In addition to precipitation and temperature, factors such as topography, geomorphology and human activities can cause deviations in the estimation, which requires further research. This paper provides new ideas and methods to analyze spatial correlation between variables that exhibit spatial non-stationary characteristics and to obtain spatial simulation distribution of the vegetation coverage index.