祁连山北坡自然恢复杨桦林地植物功能型组成及其影响因素

依据生活型(乔木、藤本、灌木、半灌木、多年生禾草、多年生杂类草和一二年生草本)和水分生态型(旱生、旱中生、中生和湿生)将祁连山北坡次生杨桦林28个调查样地中的81个物种划分为18种植物功能型(Plant functiontypes,PFTs),并通过典范对应分析(CCA)方法研究植物功能型与环境因子间的关系.结果表明:自然恢复杨桦林地植物功能型主要集中在中生多年生杂类草(PFTs16)、湿生多年生杂类草(PFTs23)、旱中生多年生杂类草(PFTs9)和中生灌木(PFTs18)4个植物功能型上;乔、灌、草三层冠层特征和中生植物的大量出现,反映了群落植物生活型趋于复杂化和结构化,生态型逐渐向中生化方向演替的特点;土壤容重、有机碳和全氮含量主要影响植物的生活型分异特征,土壤含水量和林冠郁闭度是植物的水分生态型分异的主要环境因子,而坡位、坡度控制着群落植物总体分布格局的形成.图1表3参31

Plant Functional Types and Their Impact Environmental Factors in a Naturally Recovered Poplar - birch Woodland on the North Slope of Qilian Mountains, China

Plant functional types(PFTs) are important in understanding the dynamics and the functions of an ecosystems,which provide also useful information for ecosystem management.In 28 observation plots of a naturally recovered poplarbirch woodland on the north slope of Qilian Mountains,China,81 plant species were classified into 18 plant functional types(PFTs),according to their life forms(including arbors,lianas,subshrub,shrub,perennial grasses,perennial forbs and annual or biennial grass) and ecotypes(including xerophyte,xerophytic and mesophytic,mesophyte and hygrophyte).The relationships between PFTs and environmental factors were studied using Canonical Correspondence Analysis(CCA).The results showed that the dominant PFTs were PFTs16(mesophytic perennial forbs),PFTs23(hygrophytic perennial forbs),PFTs9(xerophytic and mesophytic perennial forbs) and PFTs18(mesophytic shrub) on the poplar-birch restoration woodland.The stratified structure with wood,shrub and herb layers indicated the plant life forms had a tendency of complication and structurization,and the emerging mesophyte plants reflected changes of the micro-environments.The distribution patterns of PFTs were controlled by the soil physical and chemical properties in that soil bulk density,soil organic carbon and content of nitrogen determined the characteristics of the plant life forms,while the soil water moisture and canopy cover were the main ecological factors that affected the distribution of ecotypes.The slope position and slope aspect controlled the plant distribution pattern and formation of the community.Fig 1,Tab 3,Ref 31