不同遥感影像空间分辨率对川西南山地常绿阔叶林有效叶面积指数估测的影响

摘要

Objective]The aim of the study was to analyze the effects of different spatial resolutions on the LAIe estimation.[Method]Effective leaf area index(LAIe)of montane evergreen broad-leaved forests in southwest Sichuan was inventoried and assessed based on 83 field plots of 20 mí20 m and spectral vegetation index(Normalised Difference Vegetation Index,NDVI;Soil Adjusted Vegetation Index,SAVI;Ratio Vegetation Index,RVI)were extracted from different spatial resolution image data of Landsat-8 (30 m),SPOT-5(10 m),Pleiades-1(2 m). Based on remotely sensed data,inventoried LAIe and auxiliary variables(eg. relief data),regress models were established by partial least multiplicative regression method.[Results]NDVI and SAVI extracted from three kinds of resolution remote sensing data were most important to LAIe estimation. The VIP value of NDVI and SAVI extracted from Landsat-8 was 1.662. The VIP value of NDVI,and SAVI extracted from SPOT-5 was 1.573. Similar to Pleiades-1,the VIP value was 1.423. According to three kinds of sensors,all correlation coefficients between NDVI,SAVI and LAIe were more than 0.8,all of which were significant. The coefficient of determination R 2 was 0.793 and precision accuracy was 79.8% for the regress model using Landsat-8 data. Likewise,the coefficient of determination R2 was 0.853 and precision accuracy was 84.4% for the regress model using SPOT-5 data. Moreover,R 2 and P of regress model using Pleiades-1 data was highest compared to other regress models,which reached to 0.898 and 89.5%,respectively.[Conclusion]Different image spatial resolution have significant effects on LAIe estimation and the performance of LAIe estimation can be improved significantly using high spatial resolution optical data,such as Pleiades-1 remote sensing data.%【目的】分析遥感影像不同空间分辨率对LAIe估测结果的影响。【方法】基于地面调查的83个20 m×20 m样地和Landsat-8、SPOT-5、Pleiades-1遥感数据，以川西南山地常绿阔叶林为研究对象，运用偏最小二乘回归分析法，估测了2 m、10 m、30 m 3种尺度（粒度）上区域森林有效叶面积指数（LAIe）。【结果】3种分辨率的遥感数据提取的植被指数NDVI、SAVI对LAIe估测最为重要（Landsat-8：NDVI、SAVI的VIP=1.662；SPOT-5：NDVI、SAVI的VIP=1.573；Pleiades-1：NDVI、SAVI的VIP=1.423）。3种传感器的NDVI、SAVI的相关系数大于0.8，均达极显著水平。对LAIe回归估测检验显示，Landsat-8的决定系数R2=0.793，精度P=79.8%；SPOT-5的决定系数R2=0.853，P=84.4%；Pleiades-1的R2高达0.898，估测精度最高，达89.5%。【结论】不同空间分辨率的影像对LAIe估测有显著影响，使用高空间分辨率数据能显著提高LAIe估测精度。