陕北黄龙山辽东栎群落优势种群生态位研究

Dominant Species Niche of Quercus liaotungensis Communities in Huanglong Mt.of Shaanxi

经实地踏查,在陕北黄龙林区选择有辽东栎林分布的环境类型6个,设置20 m×20 m的样地共30个,并通过各样地组成种类重要值的计算和排序,确定辽东栎群落中的优势种群,其中乔木层14种、灌木层27种、草本层11种。依此作为统计分析对象,对黄龙山林区辽东栎群落优势种群生态位宽度和生态位重叠状况进行研究,以揭示森林群落内种间竞争的机理。结果显示:乔木层中,辽东栎、白桦、油松种群的生态位宽度较大,LNB值分别为1.4611、1.4132、1.2588,且两两之间生态位重叠值亦较大(Oik>0.7);灌木层中,土庄绣线菊、虎榛子、铁杆蒿和黄蔷薇等的生态位宽度大(LNB>1),是辽东栎林下常见的灌木种类;草本层中,披针叶苔草、华北风毛菊、草地早熟禾和大油芒具有较宽的生态位,LNB值分别为1.4456、1.2841、1.0603、1.0573,是草本层的优势种。结果表明,乔、灌、草三层的优势种群对当地环境具有较高的适应性和环境资源的利用能力;同层之间的生态位重叠表明在辽东栎群落发展过程中种群间对环境资源的利用性竞争不可避免。

Based on the field survey to Huanglong forest region,6 environmental types for Quercus liaotungensis were selected and 30 plots in 20 m × 20 m were investigated in those types. Then the dominant populations taken as research objects in Quercus liaotungensis community were chosen by the calculation and arrangement of the importance values of all species in those plots, that are 14 species in arbor layer, 27 species in shrub layer, 11 species in grass layer. According to those species,the niche breadth and niche overlap of the dominant populations in Quercus liaotungensis communities in this region were researched to understand the mechanism of inter-specific competition in the community. It is shown that comparing with other species,the niche breadth of Quercus liaotungensis,Pinus tabulaeformis and Betula platyphylla is bigger （LNB= 1. 461 1,1. 413 2,1. 258 8 respectively） and the niche overlap is bigger than others too（Oik〉0.7） ; the niche breadth of Spiraea pubescens,Ostryopsis davidiana ,Artemisia sacrorum and Rosa hugonis that are common species in Quercus liaotungensis communities, is bigger than other shrub species; the niche breadth of Carex lanceolata , Saussurea mongolica , Poa pratensis and Spodiopogon sibiricus is greater than other grass species （LNB=1. 445 6,1. 284 1,1. 060 3,1. 057 3 respectively）. It is concluded that the dominant populations from various layers of this community are adaptable to the local climate and those abilities to use the environmental resources are stronger than others;the niche overlap within the same layers shown the competition in the use of the environmental resources among species is not evitable in the process of the community succession.