干旱对内蒙古植被生长的累积与滞后影响评估研究

Assessment of the Cumulative and Lagging Effects of Drought on Vegetation Growth in Inner Mongolia

本文为探究干旱对植被的累积和时滞效应,以内蒙古为研究区,基于SPEI base v.2.5和GIMMS NDVI数据集,利用Sen式斜率、Mann-Kendall突变检验和偏相关分析方法,分析干旱对植被的累积和时滞效应。结果表明:内蒙古地区归一化植被指数(Normalized difference vegetation index,NDVI)年最大值随时间变化整体呈上升趋势,标准化降水蒸散指数(Standardized precipitation evapotranspiration index,SPEI)年平均值呈降低趋势,空间趋势变化上两者呈现一定的相似性;干旱的累积效应与内蒙古北部林区及西部荒漠戈壁区NDVI呈负相关,累积月数均在10—12个月;中部草原NDVI与干旱的累积滞后关系呈正相关,且干旱的累积影响大于滞后影响;农田植被NDVI与干旱的累积滞后效应均呈正相关,但相关性较弱;通过不同水分利用条件下干旱累积与时滞效应的相关性对比发现,干旱累积效应对植被的影响远大于时滞效应。

This study was aimed to explore the cumulative and time lag effects of drought on vegetation,based on SPEI base v.2.5 and GIMMS NDVI data sets,the cumulative and time lag effects of drought on vegetation in Inner Mongolia were analyzed using Sen-type slope,Mann-Kendall mutation test and partial correlation analyed methods.The result showed:The annual maximum value of the Normalized difference vegetation index(NDVI)in Inner Mongolia showed an overall upward trend over time,and the annual average value of the Standardized precipitation evapotranspiration index(SPEI)showed a downward trend,the two showed a certain similarity in spatial trend changes;The cumulative effect of drought was negatively correlated with NDVI in the northern forest areas of Inner Mongolia and the western desert and Gobi areas,but the cumulative months of drought were all 10-12 months.There was a positive correlation between NDVI and the cumulative lag of drought in the central grassland,and the cumulative effect of drought was greater than that of drought lag.Both the NDVI of farmland vegetation and the cumulative lag effect of drought were positively correlated,but the correlation was weak;Through the correlation comparison between drought accumulative and time-lag effect under different water use conditions,it was found that the impact of drought accumulation effect on vegetation was far greater than the time lag effect.