桂西南岩溶山地不同土地利用方式土壤微生物量及其活性特征

以广西平果县石漠化典型岩溶山地为研究区域,选择海拔接近的稀疏次生林地、灌丛、荒草地、裸地和农田等5种主要土地利用方式为研究对象,研究土壤微生物生物量及其活性的变异特征。结果表明:在不同土地利用方式下,随着植被的恢复,土壤养分含量不断提高,大小顺序表现为次生林>灌丛>农田>荒草地>裸地。土壤微生物量和呼吸强度变化显著(P<0.05),其中微生物量总体呈上升趋势,次生林和灌丛增幅较大,荒草地和裸地增幅较小;土壤基础呼吸强度除荒草地之外均显著增加,和土壤养分含量的变化趋势相一致。代谢熵(qCO2)变化规律不同,大小关系表现为:灌丛>农田>次生林>荒草地>裸地。不同土地利用方式下,由于相应地上、地下资源输入等环境因素的改变导致了土壤微生物量的差异性。为实现桂西南石漠化地区岩溶山地土壤生态系统的健康发展,从土壤生物学角度出发,积极推进植被生态恢复工程,尽可能减少人为活动对土地的干扰程度更有利于提高土壤质量。

Soilmicrobial biomass and active characters under different land-use types in karst mountain areas of southwest Guangxi

Five kinds of land-use types with the same altitude at typical rocky desertification mountainous region of Pingguo County in Guangxi were chosen to investigate the changes in soil microbial biomass and its differentiation characteristics under different land-use types in karst mountain areas of southwest Guangxi.Five kinds of land uses included secondary forest(SF),bushwood(B),waste grassland(WG),waste land(WL)and cropland(C).The results showed that soil nutrient contents were improved constantly with the vegetation rehabilitation in different land-use types.The rate order of soil nutrient contents was SF>B>C>WG>WL relatively.Soil microbial biomass and respiration changed significantly(P<0.05).There was an increasing trend for soil microbial biomass as a whole,secondary forest and bushwood increased more than waste grassland and waste land obviously.Except for waste grassland,soil basic respiration intensity of other land-use types increased significantly and showed the same trend.The rate order of soil nutrient contents metabolic quotient was B>C>SF>WG>WL similarly.Different environmental factors,such as the input of the above-ground and underground resources in different land-use types,which resulted in the difference of quantity of soil microbial biomass.To promote the healthy development of the soil ecosystem in karst mountain areas of southwest Guangxi,more vegetation ecological restoration projects should be implemented from the perspective of soil biology,and more human disturbance activity should be avoided at the same time.