庆阳市人工造林对物种多样性的影响

Changes of species diversity in the early stage of large-scale plantation in Qingyang City

【目的】调查人工造林后第2年和第6年样地物种组成及其多样性变化,为人工林经营可持续发展提供理论依据,并为庆阳市生态系统修复和植被恢复提供参考依据。【方法】采用样地调查法,通过调查造林地乔、灌、草3层植物种类、数量、多度,运用Shannon-Wiener多样性指数和Pielou均匀度指数、Margalef丰富度和Simpson优势度指数,分析人工造林恢复过程中物种组成及其多样性变化情况。【结果】人工造林后,林地内物种从40种增加到113种,种类增加明显。庆阳市人工造林乔木层油松、樟子松相对多度较大,为乔木层的主要优势树种;灌木层植物相对多度差异不大;草本层单科(属)物种数量占比相对较大,白莲蒿、黄蒿、冷蒿等蒿类植物为草本层优势群落。实施人工造林6 a后,样地各层物种多样性指数、均匀度和丰富度指数均高于造林初期。不同层间优势度指数、多样性指数和丰富度均表现为草本层>灌木层>乔木层,而均匀度则乔木层最高。【结论】人工造林后,随着时间推移,植被得到有效恢复,林地生态系统物种趋于丰富,稳定性趋步向好,但物种优势度降低,物种分布更趋向均匀;人工造林有利于区域生态系统物种多样性恢复。

【Objective】To investigate the species composition and diversity changes of sample plots in the second and sixth years after afforestation in Qingyang City,to provide theoretical basis for the sustain‐able development of plantation management,and to provide a reference basis for ecosystem restoration and vegetation restoration in Qingyang.【Method】The species,quantity and abundance of trees,shrubs and grasses of the afforestation land were investigated by using the sample plot investigation method.The changes of species composition and diversity in the process of artificial afforestation restoration were ana‐lyzed by using Shannon Wiener diversity index,Pielou evenness index,Margalef richness and Simpson dominance index.【Result】After artificial afforestation,the species in the forest land increased from 40 to 113.Pinus tabulaeformis and P.sylvestris var.mongolica are the main dominant tree species in the tree layer of artificial afforestation in Qingyang.After 6 years of artificial afforestation,the species diversity in‐dex,evenness and richness index of each layer of the sample plot were higher than those in the initial stage of afforestation.The dominance index,diversity index and richness of different layers were herb layer>shrub layer>tree layer,and the evenness was the highest in tree layer.【Conclusion】After artificial affor‐estation,the vegetation has been effectively restored,the species of forest ecosystem tend to be rich and the stability tends to be better with the time extension,however,the species dominance decreases,the spe‐cies distribution tends to be more uniform.Artificial afforestation is conducive to the restoration of species diversity in regional ecosystem.