1982-2016年华东地区叶面积指数变化特征及与气候因子的关系

Characteristics of LAI variation in East China and its relationship with climate factors from 1982 to 2016

为了解华东地区的植被变化特征,基于1982—2016年全球陆表特征参量卫星叶面积指数(Global Land Surface Satellite Leaf Area Index,GLASS LAI)数据,利用趋势分析方法研究过去35 a华东地区植被叶面积指数(Leaf Area Index,LAI)的时空变化特征,采用偏相关方法分析植被LAI与气候因子(温度、降水和太阳辐射)的相关性,并探究华东不同区域LAI变化的主导气候因子。结果表明:(1)华东地区年平均LAI为0.05~7.20,年最大LAI为0.04~8.60,均呈现由南向北递减态势。(2)近35 a华东地区年平均和年最大LAI均呈波动上升趋势,增加率分别为每年0.0079(p<0.05)和0.0226(p<0.05)。虽然华东北部LAI低于南部,但近35 a上升趋势明显;南部LAI虽较高,但部分区域有下降趋势。(3)年平均和年最大LAI显著增加的区域分别占整个区域的60.9%和60.5%,主要分布于江淮以北地区;两者显著降低的区域分别占8.9%和6.4%,主要集中在浙北到苏南一带。(4)不同区域年平均和年最大LAI变化的主要气候影响因子存在差异,年平均LAI主要受温度和降水影响的区域均占13.9%,主要受太阳辐射影响的区域占10.0%;年最大LAI主要受温度影响的区域占26.5%,集中分布于华东中南部。

In order to understand the characteristics of vegetation change in East China,based on the Global Land Surface Satellite Leaf Area Index(GLASS LAI)remote sensing data from 1982 to 2016,the spatial and temporal variation characteristics of vegetation leaf area index(LAI)in East China over the past 35 years were studied using trend analysis method,the correlation between vegetation LAI and climatic factors(temperature,precipitation and solar radiation)was analyzed using the partial correlation method,and the dominant climatic factors of LAI changes in different regions were explored.Results are as follows:(1)The annual average LAI in East China ranged from 0.05 to 7.20,and the multi-year average annual maximum LAI ranged from 0.04 to 8.60,both showing a decreasing trend from south to north.(2)The overall annual average LAI and annual maximum LAI in East China in the last 35 years showed a fluctuating increase trend,with growth rates of 0.0079(p<0.05)and 0.0226(p<0.05)per year,respectively.Although the LAI in the northern part of East China was lower than that in the southern part,the increasing trend was obvious in the last 35 years;the LAI in the southern part of East China was higher,but there was a decreasing trend in some regions.(3)The pixels with significant increasing trend of annual mean LAI and annual maximum LAI accounted for 60.9%and 60.5%of the whole region,respectively,and were mainly located in the north of Jianghuai regions.In contrast,the pixels with significant decreasing trend of annual mean LAI and annual maxi-mum LAI accounted for 8.9%and 6.4%,respectively,which were concentrated in northern Zhejiang and southern Jiangsu.(4)There were differences in the major climate factors affecting annual mean LAI and annual maximum LAI changes in different regions.As for annual mean LAI,the regions mainly affected by temperature and precipitation accounted for 13.9%,and the regions mainly affected by solar radiation accounted for 10.0%.As to annual maximum LAI,there was 26.5%region dominated by temperature,and they were mainly distributed in the south-central part of the study area.