新疆焉耆盆地人类活动与气候变化的效应机制

通过对新疆焉耆盆地及其周边近40a(1973—2014)的气候变化趋势检测、LUCC和生物量估算,探讨气候变化和人类活动的生态效应机制,研究区域陆地生态系统演变及其归因。分析结果表明:(1)焉耆盆地山区和平原区降水变化都有明显的突变点,并呈现增加趋势,蒸发量在山区减少,在平原区波动性减少趋势;(2)LUCC分析表明,山区裸地面积减少5.40%,冰川面积减少3.36%,高地植被面积增加8.76%;同时平原区天然绿洲面积增加1.96%,沙漠面积减少1.62%,水域面积减少1.30%,人工绿洲面积增加15.41%,湿地面积增加1.27%;(3)山区陆地生态系统对区域气候变化非常敏感,其中降水变化是决定山区地表植被生存状态和分布的重要因素;(4)人类活动的推动作用和有益气候变化的支撑是绿洲平原区生态系统好转的原因,其中人口急剧增加和社会经济快速发展,导致绿洲平原区生态系统结构及其时空分布的主要因素。焉耆盆地及其周围区域陆地生态系统的演变对气候变化和人类活动有明显的时空尺度效应,其反应程度各不相同。

Ecological effects of human activities and climate change in Yanqi Basin, Xinjiang, China

The relationships among terrestrial ecosystems, climate change, and human activities are important aspects to consider in the field of global change. Recently, it has become a hot research topic to study the effect of global change and the response of biologically distinct climate regions to the changes on different time and spatial scales. It has become especially important to study, on various spatiotemporal scales, the sensitivity of ecosystems to climate change and anthropogenic pressure in arid areas. However, it is difficult to monitor the temporal change of vegetation on different spatial scales, and as expected, the research achievements on this topic are few. In this study, the mechanisms of ecological effects on climate change and human activities in terrestrial ecosystems were investigated by combining the climate change point detection and trend test methodology; Land use and land cover change (LUCC), and biomass estimation after selecting a typical inland terrestrial ecosystem area:the Yanqi basin in Xinjiang, China. According to the degree of the effect of climate change and human activities, the research area was divided into two parts:a mountain (which was mainly affected by climate change) and plain oasis (which was mainly affected by human activities) at a contour of 1400 m above sea level. In respect to the vegetation, land cover types reflect the change in the ecological environment, and they were divided into the vegetation and non-vegetation cover types. According to type and affect, the land cover was classified as highland vegetation, artificial oasis, natural oasis, bare land, desert, water, glacier, and wetland. The main conclusions drawn from this study encompassed the recent 40 year period between 1973 and 2014 are:(1) distinct change points of precipitation and evaporation in mountain and plain areas of the Yanqi basin were detected by the Mann-Kendall-Sneyers test, the results of the nonparametric Mann-Kendall tests reveal that:the precipitation increased and the evaporation declined in mountain and plain areas in the same fashion; (2) in mountainous areas, the areas considered to be bare land and glacier decreased 5.4% and 3.36%, respectively, whereas the highland vegetation increased by 8.76%. In the plain area, the areas of the natural oasis, artificial oasis and wetland increased 1.96%, 15.41% and 1.27% respectively. The areas of desert and water decreased 1.62% and 1.30%, respectively; (3) biomass in mountain and plain areas distinctly variable, and the main cause attested as coupled effect of climate change and human activities in different scale with different spatiotemporal patterns. Terrestrial ecosystems in mountainous areas are sensitive to climate change, and precipitation is estimated to be the most important factor affecting vegetation growth and distribution; (4) the main reasons for oasis improvement in plain areas include enlarging an artificial oasis by intensified human activities and supporting favorable climate change. Among these reasons, enlargement of agricultural areas to accommodate an increased population and socio-economic development are the driving forces of structural change and the distribution of ecosystems plains. In summary, climate change and human activities are expected to affect terrestrial ecosystems according to different degrees and spatiotemporal patterns in the coming 40 years in Yanqi basin.