Abstract:In order to understand the correlation between soil organic content (SOM) and soil physical and chemical indicators and plant diversity indexes in nature recovery process of karst forest, the SOM, soil physical and chemical characters and plant diversity indexes of different forest types in Maolan National Nature Reserve of southern Guizhou Province were studied. According to importance values of species in tree layer, 41 surveying plots in the Reserve were divided into 6 types, such as Lindera communis-Liquidambar formosana forest, Loropetalum chinense-Pinus massoniana forest, Acer sp.-Celtis tetrandra subsp. sinensis forest, Koelreuteria minor-Platycarya strobilacea forest, Cornus controversa-C. parviflora forest and Dendrobenthamia japonica var. chinensis-Cyclobalanopsis glauca forest. The results showed that SOM had significant difference between A or B stratum of soil among forest types, and the species number, diameter, height and density, as well as Margalef index, Simpson index, Shannon-Wiener index and Pielou index of different forest types also had difference significance. The soil porosity, water storage capacity and main fertility indexes increased with SOM increment. Plant diversity indexes of tree layer had positive relationship with SOM, especially significant correlation with SOM in A stratum of soil, and Simpson index and Pielou index with significant correlation to SOM in B stratum of soil, while those in shrub layer and herb layer had no significant correlation with SOM. Multivariate analysis showed that total contribution rate of plant diversity indexes to SOM in A stratum of soil was in the order of shrub layer > tree layer > herb layer, and that to SOM in B stratum of soil was herb layer > tree layer > shrub layer. It was suggested that plant diversity measures of SOM management of vegetation restoration in karst region were suitable for giving priority to with tree species, and combining with shrub and herb species. Meanwhile, the SOM was influenced not only by plant diversity indexes of tree layer, but also by succession stage and structure indexes of forest, the Quadratic polynomial turning point of plant diversity indexes could become to one of reference bases of species quantitative management in karst rocky desertification control engineering.
