【摘要】 为了明确喀斯特草地群落多样性海拔特征及其与土壤的互动效应,采用生态学统计与排序分析,连续3年研究了桂西北喀斯特山地草地群落多样性海拔特征及土壤理化性质特征,并探讨了群落多样性与土壤理化性质之间的关系。结果表明,不同海拔草地根长、高度、地上和地下生物量在2015-2017年呈现增加的趋势,但增幅不明显,3年平均值基本表现为中海拔>低海拔>高海拔,并且不同海拔差异均显著(P<0.05)。不同海拔草地土壤全碳、全氮、全钾、碱解氮和速效磷均表现为中海拔>高海拔>低海拔,不同海拔草地土壤全碳、全氮、全钾、碱解氮和速效磷含量差异均显著(P<0.05);土壤pH值呈相反的变化趋势,而土壤全磷在不同海拔之间差异不显著(P>0.05)。不同海拔草地丰富度指数、均匀度指数和多样性指数均表现为中海拔>高海拔>低海拔,而优势度指数呈相反的变化趋势。相关性分析表明:植被多样性各指标和生物量均与pH之间存在负相关关系,与土壤理化性质等均呈正相关关系。物种丰富度指数(S)和多样性指数(H)与土壤理化性质的相关系数绝对值均高于优势度指数(D)和均匀度指数(E);其中土壤全碳和全氮与根长和生物量呈显著正相关(P<0.05),由此可知全碳和全氮是影响根长和生物量的主要土壤因子。冗余分析(RDA)表明植物群落多样性与土壤理化性质均呈正相关(除了pH);沿着RDA的第1排序轴,随着显著性影响因子(土壤理化性质)的增加,植物丰富度指数逐渐增大,其中相关性最大的是全碳及全氮,这是影响研究区植物群落分布的主要因子。更多还原

【Abstract】 In order to clarify the elevation characteristics of grassland community diversity and its interaction with soil, this study used classical statistical analysis and sequencing analysis to study the elevation characteristics and soil physical and chemical propertiesof grassland community diversity in the karst mountains for three consecutive years(from 2015 to 2017), and discussed the relationship between community diversity and soil nutrient. Our results as followed:(1) The root length, height, aboveground and underground biomass of grassland at different elevations showed a trend of increase from 2015 to 2017, and the increase effect was not obvious. The three-year average was basically shown as medium elevation>low elevation>high elevation, and the difference was significant at different elevations(P<0.05). The contents of total carbon, total nitrogen, total potassium, alkali-hydrolyzed nitrogen and available phosphorus in soil of grasslands at different elevations were all expressed as medium elevation>low elevation>high elevation, and the contents of total carbon, total nitrogen, total potassium, alkali-hydrolyzed nitrogen and available phosphorus in soil at different elevations were significantly different(P<0.05). pH value of soil showed an opposite trend, while the difference of total phosphorus in soil was not significant at different elevations(P>0.05). The richness index, evenness index and diversity index of grassland at different elevations was medium elevation>low elevation>high elevation, while the dominance index showed an opposite trend. Correlation analysis showed that soil physical and chemical properties was significantly correlated with soil plant diversity, and soil physical and chemical properties contributed the most to plant community diversity(the absolute value of its correlation coefficient was the largest). Redundancy analysis showed that there was a positive correlation between plant community diversity and soil nutrient content(except pH). Along the first sequencing axis of RDA, with the increase of significant influencing factors(soil physical and chemical properties), the plant richness index gradually increased, and plant richness index was negatively correlated with pH. Among them, total carbon and total nitrogen was the most correlated with richness index. Therefore, total carbon and total nitrogen are the main factors influencing plant diversity in this region.更多还原