基于地形汇流值的东北天然次生林主要树种的生态位

以不同汇流值梯度作为资源轴,以树种重要值为生态位计测的资源状态指标,在集水区尺度上分析了东北天然次生林群落中主林层和演替层11个主要树种(水曲柳、胡桃楸、黄檗、紫椴、糠椴、山杨、白桦、枫桦、春榆、色木槭、蒙古栎)的生态位。提出相对汇流值生态幅和汇流值竞争指数的概念来丰富生态位的测度指标。研究结果显示:在各项生态位指标计算中,主林层以色木槭、蒙古栎以及先锋树种山杨和白桦为主,演替层则以色木槭、春榆、水曲柳、紫椴等原始阔叶红松林的主要阔叶伴生树种占优;另一方面,以群落分层为资源位,主林层和演替层各树种生态位的差异揭示了主要乔木树种在该地区天然次生林群落的演替系列中对资源的占有与利用的情况及其发展变化趋势。在集水区尺度上采用汇流值作为生态位的空间维度能够较好地反映植物种群在不同地形和水分梯度上生态位的时空分布特性。

Determining niches of the major tree species based on a flow accumulation technique in a natural secondary forest in Northeastern China

We studied niche characteristics of key arbor tree species including Fraxinus mandshurica, Juglans mandshurica, Phellodendron amurense, Tilia amurensis, Tilia mandshurica, Populus davidiana, Betula platyphylla, Betula costata, Ulmus pumila, Acer mono and Quercus mongolica that represent natural secondary forests in Northeastern China. We conducted these studies at the catchment scale, taking flow accumulation gradient as resource axes, also forest storey as the resource states. Relative flow accumulation ecological amplitude and flow accumulation competition index were proposed to enrich the measurement of niche characteristics. We found that Acer mono, Quercus mongolica and light-demanding pioneer species including Populus davidiana and Betula, platyphylla occupied dominant position in the main storey while the main associated broadleaved tree species of the primary broadleaved-Korean pine mixed forest including Acer mono, Ulmus pumila, Fraxinus mandshurica, and Tilia amurensis occupied dominant position in the succession storey. On the other hand, niche differences between main and succession storey, based on the forest storey resource theory, indicate requirement of tree species for the habitat and the variation trends of this requirement in the succession sere of the natural secondary forest community in this area. We concluded that it was effective to use flow accumulation as a spatial dimension of niche, which aims to illustrate the niche spatiotemporal patterns among different tree species under the topographic and moisture gradients at a catchment scale.