水土保持研究

地处青藏高原东缘且作为重要生态屏障的川西高原生态环境脆弱,属全球变化敏感区,但由于2000年之前MODIS数据的缺失,限制了川西高原针对大范围较高分辨率数据进行植被气候响应的研究。为研究其长期的植被时空格局及其对气候变化的响应,基于增强型自适应反射率时空融合模型(Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model,ESTARFM),根据MODIS NDVI(500 m)数据得到研究区1995年GIMMS NDVI3g(8 km)的高空间分辨率数据(500 m),并结合年均气温和年降水量开展川西高原1995—2015年植被时空格局及其对气候变化响应的研究。结果表明:(1)ESTARFM模型融合的GIMMS NDVI3g与真实MODIS NDVI数据吻合度较高,融合结果可用于地形复杂的川西高原植被变化的研究。(2)1995—2015年川西高原植被覆盖呈现沿海拔梯度先升高后降低的垂直分布特点,植被变化趋势稳定;(3)1995—2015年川西高原年均气温和年降水量空间分布特征主要表现为西部年均气温和年降水量低于东部。植被覆盖对年降水量的变化较年均气温更加敏感,植被覆盖与年均气温呈正相关的区域占14.9%,与年降水量呈正相关的区域约占35.4%。总体而言,川西高原总体植被覆盖程度较好,且变化趋势稳定。年降水量相较于年均气温影响植被变化更明显。

The western Sichuan Plateau, as an important ecological barrier located on the eastern edge of the Qinghai—Tibet Plateau, is eco-environmental fragile and belongs to a sensitive area in globally change. However, due to the lack of MODIS data before 2000, studies on vegetation climate response in the western Sichuan Plateau were restricted based on a large range of higher resolution data. In order to study its long-term spatiotemporal pattern of vegetation and its response to climate change from 1995 to 2015, we employed MODIS NDVI(500 m)data to obtain high spatial resolution data(500 m)of 1995 GIMMS NDVI3g(8 km)of the study area based on the Enhanced Adaptive Reflective Temporal Adaptive Reflectance Fusion Model(ESTARFM), combined annual average temperature with annual precipitation to study the spatial and temporal pattern of vegetation and its response to climate change in the Western Sichuan Plateau from 1995 to 2015. The results show that:(1)the GIMMS NDVI3g fused by ESTARFM is in relatively good agreement with the actual MODIS NDVI data; the fusion results can be applied in estimating the vegetation of the Western Sichuan Plateau with complex terrain;(2)from 1995 to 2015, the vegetation cover of the Western Sichuan Plateau distributed a vertical characteristic which increased first and then decreased and its variation presented the trend to become stable along the elevation gradient;(3)with respect to the spatial distribution of annual average temperature and annual precipitation in the Western Sichuan Plateau from 1995 to 2015, annual average temperature and annual precipitation in the west were lower than east; vegetation coverage was more sensitive to annual precipitation change than annual average temperature change; the area where vegetation coverage was positively related to annual average temperature accounted for 14.9%, the area where vegetation coverage was positively related to annual precipitation accounted for about 35.4%. In general, the vegetation coverage of Western Sichuan Plateau is in good condition and has a stable change tendency. The influence caused by annual precipitation on vegetation change is more obvious than by average annual temperature.