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

摘要

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.%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∶P＞C∶N＞N∶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.