川北白云山地区不同密度下亮叶桦人工林群落结构和物种多样性

【目的】对川北白云山地区20年生亮叶桦Betule luminifera不同密度人工林群落结构及物种多样性进行探究,以期为该区亮叶桦人工林可持续经营提供依据。【方法】采用典型样地法,分别选择川北白云山地区现存的低密度(1 050~1 150株·hm~(-2))、中密度(1 450~1 550株·hm~(-2))及高密度(2 150~2 250株·hm~(-2))亮叶桦人工林群落作为研究对象,研究川北白云山地区不同密度下亮叶桦人工林群落结构和物种多样性特征。【结果】共记录到植物110种,隶属于52科91属。高、中和低密度下群落的物种数依次为59、42和57种;从群落结构来看,中、高密度下群落物种多集中于中径级,即胸径为5,11)cm,低密度下群落物种多集中于高径级,即胸径为11,17)cm,3种密度下群落物种的高度级结构相似,物种多集中于中高度级,即高度为9,13)m;不同密度下群落各层次物种丰富度指数(D)、Shannon-wiener指数(H)和Simpson优势度指数(H')等均表现为乔木层灌木层草本层;在乔木层中,群落各物种多样性指数在中密度下最高,低密度次之,高密度最低;草本、灌木层D和H均表现为:低密度中密度高密度。【结论】中等密度(1 450~1 550株·hm~(-2))更利于川北白云山地区亮叶桦人工林多样性的维持及树种的自然更新。

Community structure and species diversity of Betula luminifera plantation under different stand densities in Baiyunshan, north Sichuan

Objective] In order to provide a scientific basis for sustainable management of Betula luminifera plantation, we studied the effects of different stand densities on community structure and species diversity of 20-year-old B.luminifera plantation in Baiyunshan, north Sichuan.Method] Using the typical sampling method, the community structure and species diversity of B.luminifera plantation under low density (1 050-1 150 trees·hm-2), medium density (1 450-1 550 trees·hm-2) and high density (2 150-2 250 trees·hm-2) in Baiyunshan were studied.Result] In total, 110 species belonging to 52 families and 91 genera were recorded.There were 59, 42 and 57 species under high, medium and low densities respectively.In terms of community structure, most species in communities of medium and high densities were of medium diameters 5,11) cm, while most species in communities of low density were of large diameters 11,17) cm.Communities of three different densities were composed of species with similar heights, mostly ranged from medium to high height 9,13) m.The species richness indexes (D), Shannon-wienner indexes (H) and Simpson indexes (H′) were all in the order of tree layerlow density>high density, while in the shrub and herb layers, the indexes of D and H were in the order of low density>medium density>high density.Conclusion]Medium density is most conducive to the maintenance of species diversity and the natural regeneration of B.luminifera plantation in Baiyunshan, north Sichuan.