The State Key Laboratory of Remote Sensing Science, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing, China.
Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, Qinghai, China; Department of Ecology, College of Urban and Environmental Sciences, Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, China.
Sci Total Environ. 2018 Jun 1;625:1361-1368. doi: 10.1016/j.scitotenv.2018.01.034. Epub 2018 Jan 12.
The distributions of many species show climate-driven shifts towards higher elevations, but evidence for elevational shifts is scarce for the alpine grasslands on the Qinghai-Tibetan Plateau. The upward shift of alpine grassland distribution from 2000 to 2014 was assessed with field measurements and satellite remote sensing data obtained across six elevational transects on the Qinghai-Tibetan Plateau. The aboveground biomass (AGB) of alpine grasslands varied with altitude and its data produced a bell-shaped curve. This was mainly due to the elevational dependency of climate change at the surface (i.e., producing drier climate at low elevations and wetter climate at middle elevations). The normalized difference vegetation index (NDVI) derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) exhibited a positive exponential relationship with the AGB of alpine grasslands. Overall, MODIS NDVI initially increased, then peaked at median altitude sites, then decreased with altitude on each elevational transect. MODIS NDVI at the upper limit of alpine grassland distribution did not show a significant increasing trend from 2000 to 2014, even though land surface temperature increased and precipitation remained approximately constant. High spatial resolution Landsat data supported this result. Further analyses of MODIS NDVI at all other sites found no general increase in AGB towards higher elevations. The results suggest that the distribution of alpine grasslands on the Qinghai-Tibetan Plateau did not show an upward shift despite rapid climate warming having occurred from 2000 to 2014.
许多物种的分布呈现出向高海拔地区转移的气候驱动趋势，但青藏高原高山草原的海拔迁移证据却很少。通过在青藏高原六个海拔梯度上的实地测量和卫星遥感数据，评估了从 2000 年到 2014 年高山草原分布的向上迁移。高山草原的地上生物量（AGB）随海拔而变化，其数据呈现出钟形曲线。这主要是由于地表气候变化的海拔依赖性（即在低海拔地区产生干燥气候，在中海拔地区产生湿润气候）。从中分辨率成像光谱仪（MODIS）得出的归一化差异植被指数（NDVI）与高山草原的 AGB 呈正指数关系。总体而言，MODIS NDVI 在每个海拔梯度上最初增加，然后在中海拔站点达到峰值，然后随海拔下降。在高山草原分布的上限处，MODIS NDVI 从 2000 年到 2014 年并没有显示出显著的增加趋势，尽管地表温度升高，降水基本保持不变。高空间分辨率的 Landsat 数据支持了这一结果。对所有其他地点的 MODIS NDVI 的进一步分析发现，向更高海拔地区的 AGB 并没有普遍增加。研究结果表明，尽管 2000 年至 2014 年期间气候迅速变暖，但青藏高原高山草原的分布并未向上迁移。
