近16年金沙江流域植被覆盖时空特征及其对气候的响应

Spatial-temporal Characteristics of Vegetation Coverage and its Response to Climate from 2000 to 2015 in Jinsha River Basin, China

植被覆盖度是生态系统变化的主要指标之一。改善植被观测的时空尺度和植被动态变化及其驱动因素的方法,能够为我们提供更多植被变化的信息,有利于更好地了解该地区生态环境的特征和变化。基于MODIS-EVI数据,使用Sen和Mann-Kendall模型,结合偏相关分析和灰色关联分析(GRA)等方法,探索了金沙江流域近16年植被覆盖的时空演变特征及其气候驱动力。结果表明:(1)在近16年中,金沙江流域的植被覆盖总体上呈增加的趋势,EVI增速为0.011/10a;(2)植被覆盖改善区和退化区面积分别占总面积的55.53%和28.95%;(3)植被覆盖受气温和降水驱动的区域分别占总面积的32.627%和28.265%。在半干旱区,植被覆盖变化主要受降水的影响,而在半湿润和湿润区主要受温度的影响,但地形和植被类型会改变气候与植被覆盖之间的相关性;(4)半干旱区植被覆盖对气候的响应不明显,在半湿润和湿润区植被覆盖对温度的响应要慢于降水,响应时间也随海拔和植被类型的不同而变化。高海拔地区的植被对气候因素的响应要快于低海拔地区,农作物和草地对气候的响应更快,针叶林和混交林对温度的响应要快于降水。

Vegetation coverage is one of the main indicators of ecosystem change. Improving the spatiotemporal scales of vegetation observations and the methods of dynamic changes of vegetation and their driving factors can provide more information about vegetation changes, and better understand the characteristics and changes of the ecological environment in the region. The purpose of this study is to evaluate spatial-temporal changes of vegetation coverage and its driving factors in Jinsha River Basin(JRB) from 2000 to 2015, China. The evaluation will be performed using the enhanced vegetation index(EVI) of moderate resolution imaging spectroradiometer(MODIS), Sen and Mann-Kendall model, partial correlation analysis and grey correlation analysis(GRA) method. The Spatiotemporal variation of vegetation coverage were examined by using Sen and Mann-Kendall model, partial correlation analysis and GRA method were applicated to evaluate the driving factors of vegetation coverage change and its time lag to climate at pixel, ecological zone scale in JRB for growing season. The characterization and spatial distribution of the response period of vegetation coverage to climatic factors were performed through the GRA method. The results indicated that, vegetation coverage of the study area generally increased in the past 16 years, with a tendency being 0.011/decade. The areas with vegetation coverage showed improvement and degradation accounted for 55.53% and 28.95% of the total study area, respectively. The air temperature driving zoon(32.627%) was more than the precipitation driving zoon(28.265%). Vegetation coverage change was mainly affected by precipitation in semi-arid areas, while it was mainly affected by temperature in semi-humid and humid areas, but the correlation between climatic factors and vegetation was affected by topography and vegetation types. The time lag analysis indicated that the response of vegetation coverage to climate was not significant in semi-arid areas and the response of vegetation coverage to temperature was slower than cumulative precipitation in most semi-humid and humid areas, and response time of vegetation to climatic factors varied with altitude and vegetation types.