高寒草甸退化草地植被与土壤因子关系冗余分析

旨在研究高寒草甸退化草地植被与土壤因子的关系,设置研究样地、观测植物群落特征、采集土样、分析土壤主要物理化学性质,依据数量生态学基本原理,利用退化草地植被—土壤因子数据矩阵进行冗余分析。结果表明:高寒草甸群落莎草科高山嵩草、禾本科垂穗披碱草优势度随草地退化程度的加剧而降低,杂类草黄帚橐吾、豆科黄花棘豆优势度则呈相反变化趋势;RDA排序图中,第1排序轴反映高寒草甸退化程度及土壤温度、容质量、土壤含水量、全氮等因子的综合变化;第2排序轴反映土壤机械组成的综合变化。第1、第2排序轴解释74.5%的植被变化和83.2%的植被—土壤因子关系,并表明退化草地植被与土壤因子间极显著相关;莎草科、禾本科植物与土壤有机碳、全氮、土壤含水量等极显著正相关,与容质量、土壤温度极显著负相关;杂类草及豆科植物与土壤有机碳、全氮、土壤含水量等极显著负相关,而与容质量、土壤温度极显著正相关;13个土壤因子边际作用检验表明,土壤温度、容质量、有效氮、全氮等与退化草地植被的关系更密切。利用退化草地植被—土壤因子数据进行冗余分析反映出退化草地植被与土壤因子间关系密切,不同土壤因子对草地植被分布的影响不同。

Redundancy Analysis on Relationships Between Grassland Vegetation and Soil Factors on Degraded Alpine Meadow

In order to study the relationships between vegetation and soil factors on alpine meadow degraded grassland, the study plots were set up to observe the characteristics of plant community. Soil samples were collected and the main physical and chemical properties of soil were analyzed. Using degraded grassland vegetation-Matrix and based on the basic principles of quantitative ecology, the redundancy analysis was conducted.The results showed that the dominance degree of alpine meadow plant community decreased with aggravation of the grassland degradation , such as Kobresia pygmaea of sedge family and Elymus nutans of the grass family. On the contrary, poisonous forbs showed conspicuous increasing tendency, such as Ligularia virgaurea of forb and Oxytropis ochrocephala of pea family. In the RDA sorting map, the first ordinal axis reflected the degradation degree of alpine meadow and the synthesize variation of soil temperature, bulk density, soil water content, total nitrogen and other factors; the second order axis reflected the comprehensive change of soil mechanical composition. The first and second sorting axes could explain 74.5% of the vegetation variation and 83.2% of the vegetation-soil relationship. The results also showed that extremely significant correlation between the degraded grassland vegetation and soil factors, extremely significant positive correlation between Cyperaceae and Gramineae plants with soil organic carbon, total nitrogen and soil water content, and extremely significant negative correlation with bulk density and soil temperature. In addition, there was a extremely significant negative correlation between forbs and leguminous plants with soil organic carbon, total nitrogen and soil water content,an extremely significant positive correlation with bulk density and soil temperature.The results of 13 soil factors marginal test also showed that soil temperature, bulk density, available nitrogen, total nitrogen were more closely related to degraded grassland vegetation. Redundancy analysis of degraded grassland vegetation-soil factor data reflected the close relationship between degraded grassland vegetation and soil factors, and different soil factors had different effects on grassland vegetation distribution.