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林窗是森林群落物种多样性维持中十分重要的结构,但其本身物种多样性的维持机制尚不清楚,可能与相邻群落的物种丰富度、林窗面积以及土壤和地形因子等有关。本文选取浙江天童20 ha森林动态监测样地内的84个冠林窗作为研究对象,分析了林窗内部以及不同距离邻域内的物种组成,选取包含大部分林窗内物种(≥75%),并且对林窗内物种丰富度影响最大的邻域作为相关邻域(林窗周围成熟植株通过种子传播影响林窗物种丰富度,把距离冠林窗边缘5 m范围内的区域作为种源效应邻域;由于距离林窗较近,物种组成与林窗形成时仍存活个体的物种组成相似,故把距离冠林窗边缘4 m范围内的区域作为距离效应邻域),然后计算种源效应邻域内成熟植株的物种丰富度、距离效应邻域内所有植株的物种丰富度、冠林窗的面积、地形因子(海拔、坡度、坡向、凸度)和土壤因子(p H值、全氮、全碳、全磷),最后对11个潜在的影响因素进行随机组合,构建广义线性回归模型,筛选最优模型(AICc最小)进行分析。结果显示:种源效应邻域内成熟植株的物种丰富度和冠林窗面积显著影响林窗内物种丰富度,其他因素并未对冠林窗内物种丰富度产生显著影响。上述结果说明,冠林窗面积的大小以及外部种源的丰富程度是决定冠林窗内物种丰富度的主要因素,其他因素可能只产生间接影响。
Gap is a very important structure for the maintenance of species diversity in forest communities. However, the maintenance mechanism of its own species diversity is not yet clear, which may be related to the species richness, gap area and soil and topographical factors in adjacent communities. In this paper, we selected 84 Corolla forest in the 20 ha forest dynamic monitoring plots of the Tiantong, Zhejiang Province as the research object, and analyzed the species composition within the forest gaps and neighborhoods with different distances, including most of the species (≥75%), The neighborhood which has the most influence on the species richness in the alpine window is regarded as the relevant neighborhood (the mature plants around the alpina affect the species richness of the alpine meadow through the propagation of seeds, and the area within 5 m from the edge of the canopy forest window serves as the source effect neighborhood . Because the species composition is similar to that of individuals still alive when the gap was formed, the area within 4 m from the edge of the Gap in the forest is considered as the distance effect neighborhood, and then the neighborhood of the source effect is calculated The species richness of mature plants, the species richness of all the plants within the distance effect, the area of canopy gaps, topographical factors (elevation, slope, aspect and crown) and soil factors (p H, total nitrogen, , Total phosphorus). Finally, 11 potential influencing factors were randomly combined to construct a generalized linear regression model and the optimal model (AICc minimum) was selected for analysis. The results showed that the species richness and crown forest window area of mature plants in the neighborhood of provenance effect significantly affected the species richness in the gap and other factors did not significantly affect the species richness in the canopy gap. The above results show that the size of the crown forest window area and the abundance of external provenances are the main factors that determine the species richness in the canopy gap. Other factors may have only indirect effects.