基于生态化学计量学的土壤-植物系统在退化草地群落演替中的养分响应

以吉林省西部退化草地为研究对象,基于生态化学计量学理论,分析吉林省西部退化草地群落演替各个阶段,土壤和优势物种(羊草)根、茎、叶中C、N、P元素含量及其比值的生态化学计量特征,以及随着演替的进行,C、N、P元素含量及其比值的变化特征。结果表明:吉林西部退化草地中土壤和根C、N、P元素含量低于我国元素含量均值,其中,P元素属于极贫乏水平。随着草地演替程度的加深,羊草根、茎、叶中N、P元素含量呈先降低后升高的变化趋势。土壤C∶N、C∶P和N∶P远低于我国土壤均值,并且C∶PC∶NN∶P。从草地系统中土、根、茎、叶元素比值来看,C∶P与N∶P在土壤中最低,根系中最高。从N:P来看,羊草在A1(羊草群落)阶段受到N元素的限制,在A2(羊草+虎尾草群落)、A3(虎尾草+羊草+碱茅群落)和A4(碱茅+虎尾草+碱蓬+羊草群落)阶段受到P元素的限制,在演替程度最大的A5(碱蓬+碱茅+虎尾草+羊草群落)阶段受到N、P两种元素的限制。

Research on Nutrient Responses of Soil-Plant System in Community Succession of Degraded Grassland Based on Ecological Stoichiometry

Based on ecological stoichiometry,we studied the various stages of community succession of degraded grassland in western Jilin province,and analyzed the ecological stoichiometry characteristics of C,N and P elements and their ratios in soil and the dominant species'(Leymus chinensis) root,stem and leaf system.The results of the study show that the content of C,N and P elements in the soil and Leymus chinensis root is much lower than the average of the soil in China,and the content of P element belongs to a very poor level.In the community succession process,both the content of N and P elements in Leymus chinensis root,stem and leaf shows the first reducing and then increasing trend.C ∶ N,C ∶ P and N ∶ P ratios in the soil are much lower than the average of the soil in China,and the order is C ∶ P＞ C ∶ N＞ N ∶ P.Among soil,root,stem and leaf,C ∶ P and N ∶ P ratios in the soil are the lowest,while the highest ratio is in the root.Leymus chinensis is limited by N element at A1 stage,limited by the P element at A2 stage,A3 stage and A4 stage,and limited by the N and P elements at extremely serious A5 stage.