生态输水对青土湖周边区域植被覆盖度的影响

Effect of Ecological Water Conveyance on Vegetation Coverage in Surrounding Area of the Qingtu Lake

以人工干预的形式输水恢复退化的生态是目前缓解生态问题的一种有效方式。石羊河尾闾湖——青土湖是典型应用案例之一,生态输水对区域各种环境机制如何影响备受关注。本文利用青土湖1987—2016年Landsat影像反演植被覆盖度（FVC）,首先探究FVC总体动态变化特征,其次分析其变化除受气候因素的影响外与生态输水之间的关系。研究显示：30 a来青土湖周边区域平均植被覆盖度由10%左右增加到20%以上;2010年前后植被覆盖度变化趋势明显不同。利用趋势分析对比2010年9月生态输水前后植被覆盖度的变化特征,结果表明：尽管气候变化是影响大范围植被覆盖度的主要因素,但在该研究中气候变化对青土湖周边植被覆盖度上升的影响较弱;植被覆盖度主要在靠近湖区区域显著增加,生态输水是其增加的主要影响因素。2010年生态输水前年平均植被覆盖度变化趋势不明显,2010年生态输水后呈显著上升趋势。

Ecological water conveyance is an effective way to alleviate ecological problems in the form of human intervention to regenerate the degenerated ecology,and it is applied in the surrounding area of the Qingtu Lake,the tail-end lake of the Shiyang River in Minqin County,Gansu Province. The effect of ecological water conveyance on the ecology and environment in the region has attracted much attention. In this paper,the inversion of vegetation coverage（ FVC） was reconstructed using the Landsat images in the surrounding area of the Qingtu Lake during the period from 1987 to 2016. The characteristics of the overall dynamic change of FVC were firstly explored,and then the relationship between such change and the ecological water conveyance was analyzed. The results showed that the average vegetation coverage in the surrounding area of the Qingtu Lake was increased from about 10% to 20%in the past 30 years. The change trend of vegetation coverage before and after 2010 was obviously different. The trend analysis was used to compare the characteristics of vegetation cover before and after the ecological water conveyance in September 2010,and the results showed that the effect of climate change on the vegetation coverage in the study area was slight although climate change was the main factor affecting the large-scale vegetation coverage.The vegetation coverage was mainly increased in the area near the lake,and the ecological water conveyance was the main factor affecting its increase. The change of annual vegetation coverage before the ecological water conveyance in 2010 was not obvious,but after that it was in a significant increase trend.