岷江上游景观格局与土壤侵蚀变化——以杂古脑流域为例

目的]探索不同景观格局对流域土壤侵蚀过程的影响及动态变化,为岷江上游的生态保护和恢复工作提供依据。方法]应用景观生态学理论与通用土壤流失方程(USLE)分析岷江上游杂古脑流域1990年和2015年的景观格局变化与土壤侵蚀变化。结果]杂谷脑流域景观类型动态主要表现为草地面积由70 125hm~2增加到82 568hm~2,林地和耕地面积少量增加,未利用的其他地类面积减少了12 542hm~2。该区域25a来植被覆盖度显著提高,土壤侵蚀程度显著下降;2015年中度侵蚀强度以上的土壤侵蚀发生面积均出现下降,极强度侵蚀活动的发生面积下降了36 102.69hm~2。结论]25a间杂古脑流域以草地为主的植被恢复和景观格局变化,有效降低了该区域的土壤侵蚀强度,减少了水土流失。

Chang of soil Erosion and Landscape Pattern in Upper Reaches of Minjiang River -A Case Study at Zagunao Watershed

Objective] To explore the impact and dynamic changes of landscape patterns on the soil erosion process, in order to provide a basis for ecological protection and restoration in the upper reaches of Minjiang River. Methods] Landscape ecology theory and universal soil loss equation were applied to analyze the changes of soil and water loss and landscape pattern in Zagunao watershed in the upper reaches of Minjiang River between 1990 and 2015. Results] The soil and water loss and landscape pattern of Zagunao Watershed changed obviously during the period from 1990 to 2015. The area of grassland increased from 70125 hm to 82568 hm, and the area of forest and farmland increased slightly. The area of unused land and other land reduced 12542 hm. The vegetation coverage had increased while the soil erosion had decreased significantly during the past 25 years. The area of soil erosion with moderate erosion intensity or higher had decreased, and the area of extreme erosion reduced 36102.69 hm.Conclusion] The restoration of grassland effectively reduced the amount and intensity of soil erosion in the study area during the past 25 years.