气候变化背景下横断山区植被叶面积指数时空变化特征分析

Spatio-temporal Variation of Vegetation LAI in Hengduan Mountains under the Background of Climate Change

叶面积指数作为陆地生态过程的重要参数,对生态系统碳循环和区域水土保持具有重要意义。基于MOD15A2H/LAI遥感数据集,利用Theil-Sen media斜率分析、Mann-Kendall趋势检验法以及相关分析法,研究了2001~2018年横断山区植被LAI时空分布格局及变化趋势,根据气象数据、土地覆盖数据和DEM数据,重点分析了横断山区植被LAI对气候变化的响应。结果表明:(1)2001~2018年横断山区植被LAI均值为1.22,空间上呈由北向南逐渐递增的分布特征;(2)横断山区植被LAI受地形影响明显,植被LAI值随海拔升高表现为“升高-降低-稳定”的特征,随坡度增加植被LAI值呈上升趋势;(3)近18a横断山区植被LAI整体以0.07·(10a)^(-1)的速率增加,其中68.92%的区域呈增加趋势,31.08%的区域呈退化趋势;(4)横断山区植被LAI与气温和日照时长呈正相关关系,与降水呈负相关关系。在P<0.05显著性水平下,植被LAI与气温、降水和日照时长的显著相关面积比例依次为22.7%、33.58%和31.80%,表明植被LAI受降水和日照时长影响较大,气温的影响相对较弱。

As an important parameter of terrestrial ecological processes,leaf area index(LAI)is of great significance to the ecosystem’s carbon cycle and regional water and soil conservation.Based on MOD15A2H/LAI data set from 2001 to 2018,the spatio-temporal distribution pattern and change trend of vegetation LAI were studied.Then based on the meteorological data,land cover data and DEM data,the response of LAI to climate change was analyzed emphatically by using Theil-Sen media analysis method,Mann-Kendall testing method and correlation analysis method.Results showed that:(1)the mean value of vegetation LAI was 1.22 with a spatial distribution feature of high in the south and low in the north of HM from 2001 to 2018.(2)Vegetation LAI is affected significantly by topography factor.Vegetation LAI presented a feature of“elevation-down-stability”with elevation increasing,while vegetation LAI value showed an upward trend with increasing of the slope.(3)In the recent 18 years,the vegetation LAI increased at a rate of 0.07·(10a)^(-1),among which 68.92%showed an increasing trend and 31.08%showed a degradation trend.(4)The LAI was found to be positively correlated with air temperature and sunshine duration,while negatively correlated with precipitation.At the significance level of P<0.05,the areal proportion of significant correlation LAI with air temperature,precipitation and sunshine duration were 22.7%,33.58%,and 31.80%,respectively,which indicating precipitation and sunshine duration were the dominant climate factors on LAI,and air temperature on LAI was weaker relatively.