Variation of Leaf Area Index in China from 1982 to 1999 and Its Relationship with Climate Change
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摘要: 利用1982~1999年AVHRR Pathfinder卫星遥感观测的植被叶面积指数(leaf area index,LAI)资料和中国730个气象台站的温度、降水观测资料,研究了中国不同地区(东北地区、华北地区、长江流域、华南地区和西南地区)LAI的季节、生长季和年变化,及其与气候变化(温度、降水)的关系。结果表明,在中国大部分地区,年平均LAI和生长季平均LAI均是增加的。由于区域和季节气候的差异,LAI变化趋势具有明显的空间和季节非均一性。从区域平均的角度来看,不同地区年和生长季平均LAI都有增加趋势,并且在华南地区增加最快。因而,在全球变化背景下,华南地区可能是潜在的碳汇。在季节尺度上,各地区区域平均LAI基本上都是增加的,并且都在春季增加最快。温度变化是LAI变化的主要原因。但是人类活动如农业活动、城市化等对华北平原、长江三角洲和珠江三角洲等地区LAI变化的作用不容忽视。
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关键词:
- 叶面积指数 (LAI) /
- 植被变化 /
- 季节变化 /
- 气候变化 /
- 人类活动
Abstract: Using the AVHRR Pathfinder remote sensing data of leaf area index (LAI) during 1982-1999 and observed temperature and precipitation data collected at 730 meteorological stations in China, the changes in seasonal LAI, LAI in the growing season and annual LAI are investigated in different areas of China (including Northeast China, North China, the Yangtze valley, South China and Southwest China). Their relationships with climate change (temperature and precipitation) are also explored. Results show that in most areas of China, annual LAI and LAI in the growing season has been increasing during the study period, which are mainly caused by the rising temperature. Due to the difference in seasonal and regional climate, there exist obvious regional and seasonal heterogeneities in the LAI variation tendency. From the perspective of regional averages, both annual LAI and LAI in the growing season over different regions demonstrate an increasing trend, especially in South China. Therefore South China might be a potential carbon sink under the context of global change. On the seasonal scale, regional average LAI in different sub-regions basically has been increasing as well, especially in the spring. In addition, changes in LAI are mainly attributed to the variation in temperature. However, impacts of human activities, such as agricultural activities and urbanization, on the LAI changes in the North China Plain, the Yangtze River delta and the Pearl River delta couldn't be ignored.-
Key words:
- Leaf area index /
- Vegetation change /
- Seasonal change /
- Climate change /
- Human activity
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图 2 中国地区1982~1999年的(a)年平均LAI、(b)生长季平均LAI,(c)年平均温度、(d)生长季平均温度,(e)年总降水量、(f)生长季总降水量的线性变化趋势
Figure 2. Linear variation trends of (a) annual mean LAI, (b) growing season mean LAI, (c) annual mean temperature, (d) growing season mean temperature, (e) annual total precipitation, and (f) total precipitation in the growing season during the period of 1982-1999 in China
图 3 中国地区1982~1999年的(a)春季平均LAI、(b)夏季平均LAI、(c)秋季平均LAI,(d)春季平均温度、(e)夏季平均温度、(f)秋季平均温度,(g)春季总降水量、(h)夏季总降水量、(i)秋季总降水量的线性变化趋势
Figure 3. Linear variation trends of (a-c) LAI, (d-f) temperature, and (g-i) total precipitation in spring (left panel), summer (middle panel), and autumn (right panel) during the pcried period of 1982-1999 in China
图 4 相关系数的空间分布:(a、b)年、(c、d)生长季、(e、f)春季、(g、h)夏季和(i、j)秋季LAI与温度(左列)、降水(右列)之间的相关系数(±0.46、±0.59分别和950.05%、99%0.01的显著性水平相对应)
Figure 4. Spatial distributions of correlation coefficients between LAI and (a) annual mean temperature, (c) average temperature in the growing season, (e) average temperature in the spring, (g) average temperature in the summer, and (i) average temperature in the autumn; and between LAI and (b) annual mean total precipitation, (d) precipitation in the growing season, (f) precipitation in the spring, (h) precipitation in the summer, and (j) precipitation in the autumn (±0.46 and±0.59 correspond to the 0.0595% and 0.0199% confidence significance levels, respectively)
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