甘肃亚高山云杉人工林下植物种群生态位特征

根据野外110个样方的调查数据,应用Levins、Shannon-Wiener生态位宽度指数和Levins生态位重叠指数对甘肃亚高山云杉(Picea asperata)人工林下30个种(包括15种灌木和15种草本植物)的生态位特征进行定量分析。结果表明,灌木针刺悬钩子(Rubus pungens)、箭竹(Sinarundinaria nitida)、秀丽莓(Rubus amabilis)、草本东方草莓(Fragaria orientalis)、鸭茅(Dactylis glomerata)和紫花碎米荠(Cardamine tangutorum)的生态位宽度较大,表明这些物种适应能力强,分布范围广,倾向于泛化种。生态位宽的种群可能产生较小的生态位重叠,生态位较窄的种群间也会产生较大的生态位重叠,生态位宽度与生态位重叠程度无相关性。总体上看,亚高山云杉人工林下物种间生态位重叠程度均较小,种间竞争并不激烈。从生态响应来看,灌木层的红桦(Betula albo-sinensis)幼苗和草本层的老鹳草(Geranium wilfordii)发展性最强,今后可能会发展为云杉人工林下的优势种群。

Niche characteristics of the primary understory populations of a Picea asperata plantation in the subalpine region of Gansu Province

Based on the data from 110 plots obtained from field surveys,and using the Levins and Shannon-Wie-ner niche breadth index and Levins niche overlapping index,a quantitative analysis was conducted on the niche characteristics of 30 species,including 15 shrub species and 15 herb species in the understory populations of a spruce plantation in the subalpine region of Gansu Province.In the shrub layer,Rubus pungens,Sinarundinar-ia nitida and R.amabilis had a greater niche breadth than other species.In herb layer,Fragaria orientalis, Dactylis glomerata,and Cardamine tangutorum had greater niche breadths.These species were highly adapta-ble,had broad habitats,and tended to be generalist species.The populations with greater niche breadth exhibi-ted smaller niche overlap,whereas those with smaller niche breadth exhibited larger niche overlap.Niche breadth and niche overlap did not have a positive direct liner relationship.In conclusion,niche overlap of the primary understory populations in a spruce plantation was relatively low,and interspecific competition was not intense.Betula albo-sinensis and Geranium wilfordii were more aggressive than other species based on their eco-response,and they will develop as the dominant species of main understory population in the spruce planta-tion in the future.