不同植被恢复模式土壤结构特征与健康评价

Structure Characteristics and Health Evaluation of Soil in Different Vegetation Restoration Communities

对湘西女儿寨流域不同植被恢复类型的土壤结构特征研究和健康评价的结果寝明。荒草灌丛容量最高．人工林土壤容重高于天然林及混交林，对土壤孔隙状况的改善作用表现为林分类型优于荒草灌丛类型．天然林优于人工林，0-20cm土层优于20—40cm土层；土壤团聚体平均重量直径以油桐人工林、杜仲人工林最高．马尾松天然林、毛竹杉木混交林其次．而润楠次生林、荒草灌丛、杉木人工林较低，各层土壤团聚体分形维数值大小排序为：毛竹杉木混交林〉马尾松天然林〉荒草灌丛、润楠次生林〉杜仲人工林〉油桐人工林〉杉术人工林；土壤结构健康综合评价的灰色关联分析结果表明．土壤结构以荒草灌丛最差，油桐人工林最好，其余类型介于两者之间．研究结果可为女儿寨流域及我国类似生态脆弱区的植被恢复与重建提供一定依据和参考．

It is of great importance to improve soil structure by restoring vegetation in hilly and mountainous soil erosion districts. This paper makes a careful study of the characteristics of soil structure and its health evaluation in different forest restoration communities in Nuerzhai watershed. The main results are stated in the following. Firstly, the soil bulk density of wasteland-shrub type was the highest among all vegetation types, and that of the plantations was higher than those of the natural and mixed forests. Secondly, the improving effects of vegetation restoration on the soil porosity were better in forest types than in wasteland-shrub type, better in natural forests than in plantations, and better in the soil layer of 0-20 cm depth than in that of 20-40 cm depth. Thirdly, Vernicia fordii and Eucommia ulmoides plantations had the biggest mean weight diameter values of soll aggregates, followed by Pinus massoniana natural forest and Phyllostachys edulis-Cunnlnghamia lanceolata mixed forest; however, Machilus pingii secondary forest, wasteland-shrub and Cunninghamia lanceolata plantations had the smaller mean weight diameter. And the fractal dimension of soil aggregates it. different vegetation communities shows the regularity of Phyllostachys edulis-Cunninghamia lanceolata 〉 Pinus massoniana 〉 wasteland-shrub and Machilus pingii〉 Eucommia ulmoides〉Vernicia fordii〉 Cunninghamia lanceolata. Finally, the result of soil structure and health evaluation by gray incidence analysis demonstrates that the worst soil structure took place in wasteland-shrub but the best in Vernicia fordii plantations. These results could offer some basis and references for vegetation restoration in Nuerzhai watershed and other similar vulnerable eco-regions in China.