种植巨菌草对乌兰布和沙漠植物物种多样性与土壤理化性质的影响

Effects of Planting Cenchrus fungigraminus on Plant Species Diversity and Soil Physicochemical Properties in the Ulan Buh Desert

了解种植巨菌草对乌兰布和沙漠植物物种多样性及土壤质量状况的影响,可为沙漠生态系统植被恢复与可持续经营提供依据。以巨菌草种植1 a、5 a、8 a样地为研究对象,以围封裸沙地为对照(CK),比较了CK与不同种植年限巨菌草样地植物物种多样性与土壤理化性质的差异及二者相关性。结果表明:与CK相比,种植巨菌草后更新灌草11科31属38种,优势种更替明显,改变了沙地群落结构,显著提高了各物种多样性指数;随年限增加,灌草层物种数增加,灌木层各多样性指数在5 a样地中最佳,草本层各多样性指数在8 a样地中最佳;CK与1年样地间群落相似性指数最大,而后降低。与CK相比,种植巨菌草显著改善了土壤理化环境,降低了土壤容重,提高了孔隙度、含水量、持水量及有机质、氮、磷、钾等养分;随年限增加,8 a和5 a样地土壤理化条件显著优于1 a和CK样地。冗余分析(RDA)分析结果表明灌草层丰富度指数、Shannon-Wiener多样性指数、Simpson优势度指数、Pielou均匀度指数与土壤理化因子密切相关,各指数与除容重外其他因子间均呈正相关关系。同时,1 a与5 a样地间各多样性指数及土壤因子变化幅度明显大于5年与8年样地间。综上,种植巨菌草显著改善了乌兰布和沙漠东缘植物物种多样性与土壤理化性质,随种植年限增加,群落结构与土壤环境不断改善且逐渐稳定,沙漠生态系统朝正向演替发展,5 a可达较好效果,8 a效果最佳。

Understanding the effects of planting Cenchrus fungigraminus on plant species diversity and soil quality in Ulan Buh Desert can provide a basis for vegetation restoration and sustainable management of the desert ecosystem.Using 1-year,5-year,and 8-year plots of Cenchrus fungigraminus as the research objects,and enclosed bare sand as the control(CK),we compared the differences and correlations in plant species diversity and soil physicochemical properties between CK and the sample plots of Cenchrus fungigraminus with different planting years.The results showed that compared with CK,the shrub and herb layers were renewed with a total of 38 species in 11 families and 31 genera in the sample plots with Cenchrus fungigraminus.The dominant species were significantly replaced,the community structure of the sandy land was changed,and the species richness index(D),Shannon-Wiener diversity index(H),Simpson dominance index(H')and Pielou evenness index(JSW)increased significantly.The number of species in the shrub and herb layers increased with the increase of planting years,and D,H,H',JSW of shrub layer were best in the 5-year sample plot,while the D,H,H′,JSW of herb layer were best in the 8-year sample plot.The community similarity indices were highest between CK and 1-year sample plot,and then decreased with the increase of planting years.Compared with CK,the soil physicochemical properties were significantly improved.The soil bulk density was reduced significantly,and the soil porosity,moisture content,water-holding capacity,organic matter,total nitrogen,total phosphorus,total potassium were increased significantly in the sample plots with Cenchrus fungigraminus.The soil physicochemical properties in the 8-year and 5-year plots were significantly better than those in the 1-year and CK plots.The results of Redundancy Analysis(RDA)showed that the D,H,H',JSW of shrub and herb layers were closely related to soil physicochemical factors,and each index was positively correlated with other physicochemical properties except for the soil bulk density.Meanwhile,the range variation of the D,H,H',JSW and soil properties between 1-year and 5-year plots was significantly greater than that between 5-year and 8-year plots.In summary,the planting of Cenchrus fungigraminus can significantly improve the plant species diversities and soil physicochemical properties in the eastern edge of Ulan Buh Desert.With the increase of planting years,the community structure and soil environment were gradually improved and stabilized,and the desert ecosystem developed towards positive succession.Moreover,the improvement effect reached a relatively good result in the 5-year sample plot and was best in the 8-year sample plot.