长江上游植被生态系统应对干旱的适应性与滞后性响应研究

Frequency extremely climate were projected in many regions, especially the severity drought by the global climate change in early 21st century. The drought significantly affected the process of ecosystem carbon cycle. However, the effects of drought on ecosystem were still not clear. More and more studies showed that the effects of drought on biomes are not simple negative effects. For one thing, biomes could reduce their moisture loss, change their own structure, maintain or increase their water absorption to adapt the effects of drought. People defined this phenomenon as the resilience of ecosystem. For the other thing, studies showed that the influence of climate change on bio-environment is an accumulation effect. Researchers defined the influence of previous climate factor on the current biomes' growth as the legacy effect. The ecological-environmental conditions in upper stream of Yangtze River, which is rich in natural biomes and abundant rainfall intensity, is very complex and fragile, particularly affected by the Three Gorges Project and other hydropower project in upstream. Since 21st century, frequency droughts have been projected in this area under the influence of El Nino and climate change. Based on these above, in this research, four kinds of hypothesis had been put forward to explain the resilience and lag effect of four biomes by drought in upper stream of Yangtze River in early 21th century. Then we try to develop and validate a predictive model of ecosystem based on the drought of both current and previous years. This model is particularly useful for understanding the impact of drought at the landscape scale.

在全球气候变化的背景下，21世纪初期北半球气候加速变暖，导致的干旱的频发显著的影响了植被生态系统中碳循环的过程。研究发现，干旱灾害对植被生态系统的影响并非是简单的负面影响，而是一个长期的复杂的影响过程。一方面，当气候条件变化时，植被会通过改变自身的结构，减少水分丢失，维持或升高水分吸收，从而适应干旱对生态系统造成的影响，这一现象称之为植被生态系统的适应性；另一方面，干旱灾害不仅仅影响当年的植被生长，也会影响到之后很长时间的植被生长，这一影响称之为植被响应干旱的滞后性。长江上游地区，自然植被丰富，降雨充沛强度大。受三峡工程及上游阶梯水电工程的影响，其生态环境条件复杂且脆弱。在气候变暖与厄尔尼诺的影响下，这一地区近年来干旱灾害频发。基于此，本研究针对21世纪以来长江上游地区四种自然植被应对干旱灾害的适应性与滞后性，提出植被响应的四种假设，基于植被响应规律，构建植被生态系统响应预测模型。

在全球气候变化的背景下，21世纪初期北半球气候加速变暖，导致的干旱的频发显著的影 响了植被生态系统中碳循环的过程。研究发现，干旱灾害对植被生态系统的影响并非是简单的 负面影响，而是一个长期的复杂的影响过程。一方面，当气候条件变化时，植被会通过改变自 身的结构，减少水分丢失，维持或升高水分吸收，从而适应干旱对生态系统造成的影响，这一 现象称之为植被生态系统的适应性；另一方面，干旱灾害不仅仅影响当年的植被生长，也会影 响到之后很长时间的植被生长，这一影响称之为植被响应干旱的滞后性。长江上游地区，自然 植被丰富，降雨充沛强度大。受三峡工程及上游阶梯水电工程的影响，其生态环境条件复杂且脆弱。在气候变暖与厄尔尼诺的影响下，这一地区近年来干旱灾害频发。. 本研究创新性的提出了长江上游地区土地覆被遥感监测方法和地上生物量遥感监测方法，基于该方法，对三峡库区土地覆被和地上生物量开展了动态监测分析，项目的部分成果应用在长江三峡工程生态与环境监测系统生态环境遥感监测重点站年度监测任务中。具备一定的使用价值。