农牧交错带不同植被群落对土壤微生物量碳氮磷的影响

为了解荒漠化土地植被恢复对土壤微生物量的影响,以地处毛乌素沙地南缘的榆林市沙生植物园植被恢复30年的乔木、灌木和草地3种植被群落下土壤为研究对象,分析了植被恢复对土壤微生物量碳、氮、磷含量及比值的影响及其与土壤理化性质的相关性。结果表明,农牧交错带荒漠化土地植被恢复可以明显提高表层土壤微生物碳、氮、磷的含量。土壤微生物量碳以灌木林地为最高,含量为288.35 mg·kg-1,显著高于草地和乔木,分别是乔木林地和草地的3.99和2.10倍;土壤微生物磷在三种植被群落间差异不明显;三种植被群落下土壤微生物碳氮比的高低为乔木林地草地灌木林地,土壤微生物碳磷比表现为草地略高于乔木林地和灌木林地。相关性分析结果显示微生物量碳、氮、磷与土壤理化性质相关性极为密切,其中与土壤养分各指标大多呈现极显著相关,与土壤容重多为极显著负相关。说明土壤微生物量可以作为评价土壤质量的生物学指标。

Effects of different plant communities on soil microbial biomass carbon, nitrogen and phosphorus in the agro-pastoral transitional zone of northern Shaanxi Province

To investigate the effects of vegetation restoration of the desertification land on microbial contents in the soil, soils underneath three different plant communities including arbor, shrub and grassland restored for 30 years in the south of maowusu sandy land of Yulin psammophyte garden were studied. The resulting effects of restoration on microbial biomass C, N, P, the relationship between them and the soil physicochemical properties were further analyzed. The results showed that vegetation restoration of the desertification land in agro-pastoral transitional zone had a significant promoting impact on microbial biomass C, N, P in the surface soil. The soil microbial biomass C of shrub was 288.35 mg·kg^-1, which was the highest. The soil microbial biomass N of shrub was 3.99 and 2.10 times higher than that of arbor and grassland, respectively. Difference of the soil microbial biomass P among these three plant communities was not apparent. The order of soil microbial biomass C/N ratios was as arbor>grassland>shrub. The ratio of soil microbial biomass C/P of grassland was slightly higher than that of arbor and shrub. The correlation analysis results showed that the soil microbial biomass C, N, P had close correlations with soil physical and chemical properties. The soil nutrient mostly showed extremely significant correlation, and the soil bulk density mostly had extremely significant negative correlation, which meant that the soil microbial biomass could be used as a biological index for soil quality evaluation.