近14年西南地区植被季节变化及与气候关系

Seasonal Changes of Vegetation in Southwestern China and Its Relation to Climate Factors in Recent 14 Years

针对我国西南地区植被对气候的适应性及对气候反馈的问题,基于1999~2012年归一化植被指数数据,结合同期气温和降水资料,探究该区主要植被类型对气候变化的响应方式。运用GIS和RS技术,采用最大值合成和变化斜率法,从季节尺度分析该区近14年植被覆盖的时空变化特征及与气温、降水关系。结果表明：1）近14年该区植被覆盖度四季均呈现增加趋势,其中春季增加速率最快（8.7%/10a）、趋势最为显著（P〈0.001）,秋季次之,夏季最小（4%/10a）。2）该区植被以生长季提前为主要特征,气温是影响生长季提前的主要自然因素,降水增加则促使生长季振幅增大。所有植被类型（除农林交错植被）均表现为生长季提前,农林交错植被以生长季延长为主要特征。3）植被覆盖度增加以春季为主的区域面积最大（47.39%）,分析表明生长季提前是该区植被对近14年气候变化的最主要响应方式,但这种季节响应存在显著的空间差异,若尔盖高原、四川盆地、云贵高原西部及广西丘陵大部的植被主要表现为生长季提前,而四川盆地和广西丘陵中部、及云贵高原中东部表现为生长季延长。

Aiming the issue of adaptability and response to climate in southwest China,in this study, NDVI data during 1999 -2012 and the data of temperature and precipitation in the same period was used to study response mode of main types of vegetation to climate changes. GIS and RS technologies were applied by method of maximum value composites and slope method to analyze spatial changes of vegetation cover in this area in recent 14 years and its correlation with temperature and precipitation. The results show： 1） In recent 14a,vegetation coverage of all seasons in this area presented an decreasing trend. Meanwhile,the increasing rate of vegetation coverage in spring was the most obvious （8.7 %10a. P〈0. 001） and followed by autumn,while the rate in summer was the slowest. 2） This region was characterized by its growth season bringing forward. Temperature was the main natural factor that could influence the growth season, and the increase of precipitation led to increase of growth season amplitude. Growth season bringing forward was the main characteristic of all vegetation types except for agricultural-forest vegetation that was characterized by growth season extension. 3） The vegetation coverage mainly occurred in spring with the largest part in the study area （47. 390/00）. The results exhibited that growth season been ahead of time was the major response of vegetation to climate changes in recent 14a, however, there is a significant spatial difference as seasonal response. Growth season of vegetation in the Zoige Plateau, Sichuan Basin, western part of Yunnan-Guizhou Plateau as well as most part of the Guangxi Hills displayed a trend of ahead of time,growth season of vegetation in the Sichuan Basin,central part of Guangxi Hills,central and eastern part of Yunnan-Guizhou Plateau appeared a trend of extension.