晋西黄土区陡坡植被自然恢复评价

Evaluating natural restoration of vegetation on steep slopes in the Loess Plateau,Shanxi Province

为了解黄土沟壑区35°以上陡坡植被的恢复状况,本文结合遥感和GIS技术,采用野外调查方法,于2016年6—8月,选取山西吉县蔡家川流域35°以上的阴坡、半阴坡、阳坡、半阳坡等无人为干扰的100个陡坡样地进行植被群落调查,在划分立地类型的基础上,以空间代替时间的方法分析陡坡各立地的植被覆盖度、群落恢复度(RD)和恢复速度的变化。结果表明:陡坡立地共分为3个立地类型组,分别为Ⅰ组(35°~45°)、Ⅱ组(45°~55°)和Ⅲ组(>55°);Ⅰ组和Ⅱ组植被覆盖度和生物量与Ⅲ组差异均显著(P<0.05);陡坡植被恢复在早期阶段(RD为0.1~0.3)群落恢复度较低但恢复速度快;在中期阶段(RD为0.3~0.7),恢复度、恢复速度中等;在后期阶段(RD>0.7),恢复度较高,恢复速度慢;Ⅰ组、Ⅱ组和Ⅲ组植物群落自然恢复的策略不同,Ⅰ组和Ⅱ组植被在恢复前期恢复速度最快,Ⅲ组植被在后期恢复速度较快;Ⅰ组和Ⅱ组中已存在恢复度达到0.8以上的群落,植被自然恢复的效果良好,而Ⅲ组群落最大恢复度仅达到0.5,植被自然恢复的效果并不明显。

To understand the restoration status of vegetation on steep slopes above 35°, with the application of RS and GIS tools, 100 plots with different aspects on steep slopes of Caijiachuan watershed in Jixian County of Shanxi Province were selected. On the basis of division of site types, vegetation coverage, community restoration degree （RD） and restoration speed （RS） in different habitats of steep slope were analyzed by using the method of spatial sequence instead of time succession. The results showed that steep slopes could be divided into 3 groups of site types according to different slopes, i.e. group Ⅰ （35°-45°）, group Ⅱ （45°-55°） and group Ⅲ（〉55°）. Coverage and biomass of groups Ⅰ and Ⅱ were obviously different from group Ⅲ（P〈0.05）. According to community RD and vegetation succession, recovery process was divided into early, middle and late stages. There were highest RS but lowest RD in the early stage; the moderate RD and RS in the middle stage; the slowest RS and the highest RD in the late stage. The natural restoration strategy was different for the three site types, and the RD was the highest in the early stage for both groups Ⅰ and Ⅱ, while the RD was the highest in late stage for group Ⅲ. The RD reached up to 0.8 for both groups Ⅰ and Ⅱ; for group Ⅲ, the maximum RD was only 0.5, and the effect of natural vegetation restoration was not obvious.