1999-2019年青藏高原不同植被类型NDVI时空演变特征及其对气候因子的响应

Spatiotemporal Evolution Characteristics of NDVI of Different Vegetation Types and Its Response to Climate Factors on the Qinghai-Tibet Plateau from 1999 to 2019

研究青藏高原不同植被类型NDVI时空变化特征,探讨不同植被类型NDVI对气候因子的响应机制,为青藏高原生态保护提供科学依据。基于1999—2019年的SPOT/VEG NDVI数据、植被类型和气象数据,采用线性趋势分析、Pearson相关分析及偏相关分析方法,对1999—2019年青藏高原不同植被类型NDVI时空变化特征进行了分析,并探讨了不同植被类型NDVI变化对气候因子的响应。结果表明:(1)青藏高原整体植被生长状况良好,青藏高原各植被类型生长季平均NDVI均值从高到低依次为森林(0.6)、灌丛(0.48)、草甸(0.37)、草原(0.16)、高山植被(0.13)。(2)除高山植被有轻微退化趋势外,其他植被类型均有显著改善,改善面积占比依次为灌丛58.46%(p<0.05)、森林52.78%(p<0.05)、草甸51.60%(p<0.05)、草原32.65%(p<0.05)。(3)气候因子对植被NDVI的影响具有明显的地域差异性,平均气温对青藏高原植被生长季NDVI变化的影响更为显著,且影响范围更为广阔;而降水主要影响青藏高原北部地区的草原、草甸等植被的NDVI变化。研究结果能够为青藏高原生态保护和制定科学合理的植被修复策略提供一定的方法支撑。

To study the temporal and spatial variation characteristics of NDVI of different vegetation types in the Qinghai-Tibet Plateau, explore the response mechanism of NDVI of different vegetation types to climatic factors, and provide a certain basis for the ecological protection of the Qinghai-Tibet Plateau, based on the SPOT/VEG NDVI data, vegetation types and meteorological data from 1999 to 2019, linear trend analysis, Pearson correlation analysis and partial correlation analysis methods, the temporal and spatial changes of NDVI of different vegetation types on the Qinghai-Tibet Plateau from 1999 to 2019 were examined. The responses of different vegetation types to climatic factors were analyzed and discussed. The results showed that:(1) the overall vegetation on the Qinghai-Tibet Plateau was growing well, and the average NDVI of different vegetation types during the growing season was 0.6 for forest, 0.48 for shrub, 0.37 for meadow, 0.16 for grassland and 0.13 for alpine vegetation in descending order;(2) except for the slight degradation of alpine vegetation, other vegetation types had been significantly improved, and the proportions of improved areas were 58.46% for shrub(p<0.05), 52.78% for forest(p<0.05), 51.60% for meadow(p<0.05) and 32.65% for grassland(p<0.05);(3) the effects of climate factors on NDVI had obvious regional differences;average temperature had a more significant impact on NDVI in the growing season of the Qinghai-Tibet Plateau, and the impact range was broader;precipitation mainly affected the NDVI change of grassland, meadow and other vegetation in the northern part of the Qinghai-Tibet Plateau. It can be concluded that the NDVI change of vegetation in the growing season of the Qinghai-Tibet Plateau is more affected by average temperature than precipitation in the same period. These results can provide a scientific basis for the ecological protection of the Qinghai-Tibet Plateau and the formulation of a scientific and reasonable vegetation restoration strategy.