青藏高原生态环境脆弱,对人类活动和气候变化敏感,而其植被覆盖率和物候期变化对全球生态变化具有重要的指示作用.文章基于Global Inventory Modelling and Mapping Studies(GIMMS)与Moderate-Resolution Imaging Spectroradiometer(MODIS)两种长时间序列青藏高原NDVI数据集,分析1982-2020年5-10月逐月青藏高原归一化植被指数(NDVI)的时空变化趋势及其与月降水量、月均气温和土地利用的关系.结果表明,青藏高原近40年5-10月逐月NDVI整体呈增长趋势;植被生长季初始期有所提前,并且生长季有延长趋势.近40年,5-10月逐月NDVI出现下降趋势的地区集中分布在青藏高原的西部和东南部,西部草地对气温上升的敏感性与过度放牧等人类活动的影响导致部分草地退化为荒漠,近年来水热条件的改善和生态保护政策的实施使植被有所恢复;而东南部的植被变化则主要与人类活动和气温升高有关.该研究有助于理解气候变化和人类活动对植被覆盖率的影响规律,为全球气候变化下青藏高原的生态保护政策优化提供数据支持.
Spatial-temporal Variation Characteristics and Influencing Factors of Monthly NDVI during the Vegetation Growing Season on the Tibetan Plateau from 1982 to 2020
The Tibetan Plateau has a fragile ecological environment that is sensitive to human activities and cli-mate change.Its vegetation coverage and phenological phase changes significantly contribute to indicate global ecological changes.Based on the long-term time series Normalized Difference Vegetation Index(NDVI)datasets of the Tibetan Plateau from the Global Inventory Modeling and Mapping Studies(GIMMS)and the Moderate-Resolution Imaging Spectroradiometer(MODIS),the spatiotemporal variation trend of monthly NDVI on the Ti-betan Plateau from May to October between 1982 and 2020 and its relationship with monthly precipitation,mean monthly temperature and land use were analyzed.The results indicated that over the past four decades,there has been an overall increasing trend in the monthly NDVI on the Tibetan Plateau from May to October.The initial period of the vegetation growing season has advanced,and there is a trend towards an extended growing season.Over the past 40 years,the areas with a decreasing trend in monthly NDVI from May to October are main-ly concentrated in the western and southeastern parts of the Tibetan Plateau.The sensitivity of the western grass-lands to rising temperatures,coupled with the impact of human activities such as overgrazing,has led to the deg-radation of some grasslands into deserts.However,in recent years,improvements in hydrothermal conditions and the implementation of ecological protection policies have led to some recovery of the vegetation.The vegetation changes in the southeastern region are primarily related to human activities and rising temperatures.This study contributes to the understanding of the impact patterns of climate change and human activities on vegetation cov-erage,with the aim of providing data support for the optimization of ecological protection policies on the Tibetan Plateau under the global climate change.
NETL
NSTL
万方数据
