陕北黄土丘陵区不同植被类型群落多样性与土壤有机质、全氮关系研究

为探讨陕北黄土丘陵区不同植被类型物种多样性与土壤有机质、全氮的关系，在野外调查和室内分析的基础上，采用相关性分析对5种不同植被群落特征、多样性、土壤碳氮之间的关系进行研究。结果表明：植物群落组成主要为菊科、禾本科和豆科，这3大科植物在该区具有较强的生态适应性；不同植被类型群落Gleason丰富度指数为30 a撂荒地最大，16 a撂荒地最小，Simpson指数、Shannon-wiener指数和Sheldon均匀度指数均为30 a刺槐林（Robinia pseudoacacia）最大，16 a撂荒地最小；土壤有机质、全氮含量均随土层深度增加而递减，其平均含量在0~30 cm和30~100 cm土层从大到小为30 a刺槐林>30 a撂荒地>16 a刺槐林>30 a柠条林（Caragana microphylla）>16 a撂荒地，30 a刺槐林表现出较好的土壤碳氮累积效果。相关性分析结果表明，不同植被类型群落物种多样性与土壤有机质、全氮之间显著相关（P<0.05），表明土壤有机质和全氮是影响植物群落组成和多样性的关键生态因子。

Relationships among Community Diversity and Soil Organic Matter,Total Nitrogen under Different Vegetation Types in the Gully Region of Loess Region

In order to evaluate the relationships among species diversity characteristics, soil organic matter and total nitrogen under different vegetation types in the gully region of Loess Region, five vegetation types were selected (16 a Robinia pseudoacacia, 30 a R. pseudoacacia, 30 a Caragana microphylla, 16 a abandoned land, 30 a abandoned land) based on the survey of community. Then species diversity characteristics, soil organic matter and total nitrogen were measured and calculated. Results showed that Gramineae, Compositae and Leguminosae had strong ecological adaptability. Richness index was the largest under 30 a abandoned land and the lowest under 16 a abandoned land, whereas Simpson index, Shannon-Wiener index and Sheldon evenness index were the largest under 30 a R. pseudoacacia and the lowest under 16 a abandoned land. The average contents of organic matter and total nitrogen in all tested vegetation types decreased with soil depth increasing, and were ordered as 30 a R. pseudoacacia>30 a abandoned land >16 a R. pseudoacacia>30 a Caragana microphylla>16 a abandoned land. And 30 a R. pseudoacacia showed better effect on soil organic matter and nitrogen accumulation. The significant correlations (P<0.05) among species diversity, soil organic matter and total nitrogen indicated that soil organic matter and total nitrogen were the key factors influencing plant community composition and diversity.