吉林西部草地生态系统不同退化演替阶段表层土壤有机碳变化

Changes of Surface Soil Organic Carbon in Different Degradation Succession Stages of Grassland Ecosystem in the Western Part of Jilin Province

草地退化是吉林西部主要的生态环境问题之一,改变了草地生态系统碳收支平衡。以吉林西部不同退化演替阶段的草地为研究对象,以大安市姜家甸草场为典型区,经过野外样地调查,选取40个样地,采集160份土壤样品,进行室内实验分析。土壤理化性质测定及群落植被调查结果表明,随着各群落逆行演替的进行,土壤含水率逐渐降低、土壤的透水性变差、土壤逐步贫瘠化、盖度变小,植被生物量及生物多样性先升高再降低;不同退化演替阶段期间,从羊草群落(Leymus chinense)到碱蓬群落(Suaedaglauca)直至退化为盐碱地,40cm土壤有机碳密度从羊草群落的47.72t/hm2升高到羊草-虎尾草群落的48.46t/hm2,再减少至盐碱地的27.44t/hm2,与羊草群落相比减少约42%;草地退化所形成的逆行演替对0-40cm土层土壤有机碳密度分别降低了8.45,5.72,3.68和1.74t/hm2。草地适度退化能增加草地碳储量,而过度退化则会加速草地碳库的损失。

Grassland degradation is one of the major ecological problems in the western part of Jilin Province; grassland degradation changes the carbon balance of grassland ecosystem. By taking different succession stages of grassland degradation in the western part of Jilin Province as the research object, 40 sample plots were selected, and 160 soil samples were collected for further experimental analysis via wild plots investigation in Jiangjiadian of Da＇an City. The following results are achieved through determining soil characteristic and investigating vegetation community. As converse succession is on tbe way, the water ratio of soil and coverage is decreasing, soil permeability is worse while vegetation biomass and biology diversity first go up and then fall. In different stage of degradation succession, organic carbon density in 40cm soil is increased from 47.72 t/hm2 in Leymus chinense to 48.46 t/hm2 in Carex duiuscula, and then the density is cutting down to 27.44 t/hm2 in salt flat. Converse succession caused by grassland degradation made the organic carbon density in surface soil （0-40cm） decrease 8.45, 5.72, 3.68, and 1.74t/hm2, respectively. The conclusions are listed as follows： Grassland degradation causes the large influence of organic carbon on surface soil, meanwhile has little influence on deep soil. It is not a simple carbon exposed process. Certain grassland degradation might increase the carbon reserves caused by artificial or natural impacts, while excessive degradation could accelerate the loss of grassland carbon store.