黄土丘陵沟壑区退耕地植被自然恢复过程--以吴起县双树沟流域为例

Natural succession process of vegetation on the abanded land in the Hilly-gully Region of Loess Plateau: A case study of Shuangshugou Watershed in Wuqi County

采用TWINSPAN分类法对黄土丘陵沟壑区吴起县双树沟流域30个自然恢复草地植被进行分类,并对分类后各植被群落特征和地上生物量进行统计分析。结果表明:在自然恢复条件下,随着退耕年限的不断增加,退耕地植被自然恢复依次经历了猪毛蒿群落—赖草+长芒草群落—赖草+铁杆蒿群落—铁杆蒿群落—铁杆蒿+茭蒿群落5个发展阶段,地带性植被类型铁杆蒿+茭蒿群落在研究区内开始出现,并且已经占有一定优势;随着退耕地植被自然恢复的不断进行,Margalef等丰富度指数以及Shannon-wiener等多样性指数、Pielou等物种均匀度指数和地上生物量都呈现出先减小后增大的发展趋势;在植被自然恢复的稳定阶段,虽然物种丰富度指数和物种多样性指数有一定的增加,但是相对恢复初期来讲还是有所下降,并且有达到与初期相当水平的趋势;物种丰富度指数均在第1恢复阶段最大,而均匀度指数Jsw以及Shannon-wiener指数在第5恢复阶段最高。随着退耕地植被自然恢复的不断进行,植被群落总盖度随着退耕年限的延长而不断增大。

The two-way indicator species analysis were adopted to classify the vegetation naturally recuperating on 30 sample sites of abandoned lands distributed in Shuangshugou Watershed of Wuqi County, which is located in the Hilly-gully Region of Loess Plateau. The plant community characteristics of different natural restoration grasslands and above-ground biomass were calculated. The results showed that the vegetations on the abandoned lands successfully experienced Artemisia scoparia community, Leymus scalinus and Stipa bungeana community, Leymus scalinus and Artemisia sacrorum community, Artemisia sacrorum community, Artemisia sacrorum and Artemisia giraldii Pamp community. The typical vegetation Artemisia sacrorum and Artemisia giraldii Pamp community has ap of Margalef, Shannon-wiener, Pielou and peared , and it takes great advantage in this study area. The indexes above-ground biomass manifested decrease with removal time passing by at first and then increase. Though the richness indexes and diversity indexes increased in the stable stage of vegetation restoration, there was a little lower than elementary stage. And it also had the trend to reach the initial stage. The richness indexes of the first stage were the largest, and the evenness indexes of the fifth stage were the biggest. The vegetation coverage degree became larger with the prolonging of vegetation restoration.