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为研究人工林群落的边缘效应特征,本文以川西周公山森林公园的柳杉(Cryptomeria fortunei)人工林破碎化大斑块为对象,以植株平均胸径、平均高度、平均密度、丰富度指数(D)和Shannon-Wiener指数(H)来综合衡量边缘效应深度。在实地踏查的基础上,从林缘向林内(梯度1至梯度5)设置5条样带(宽度为10 m),在每条样带中设置4个10 m×10 m的小样方进行调查。结果表明:(1)从物种组成上看,在总面积为2,000 m~2的20个小样方中共记录到111个物种,隶属于54科96属,物种数从林缘至林内递减。(2)从群落结构上看,乔木层的平均胸径从林缘至林内呈减小趋势,平均密度则相反,平均高度无显著变化;灌木层的平均密度从林缘向林内减小,平均高度无显著变化;草本层的平均密度和平均高度均呈减小趋势。(3)从物种多样性上看,总体上各层次的丰富度指数和Shannon-Wiener指数均从林缘向林内呈减小趋势,其中灌木层和草本层的变化趋势最明显;同时,林内各梯度与梯度1(林缘)的共有种和相似性系数从林缘向林内递减。(4)分析各项群落特征发现,平均高度、平均密度和相似性系数的数值在梯度2向梯度3过渡时的起伏变化最明显,推断本研究中柳杉人工林斑块的边缘深度可达林内20 m。
In order to study the marginal effect characteristics of plantation community, this paper took the fragmented large plaques of Cryptomeria fortunei plantation in Zhougongshan Forest Park in western Sichuan as an example. The average DBH, average height, average density, abundance index (D ) And Shannon-Wiener index (H) to comprehensively measure the depth of edge effect. On the basis of field investigation, five transects (width: 10 m) were set from the forest edge to the forest (gradient 1 to gradient 5), and 4 small samples of 10 m × 10 m were set in each transect survey. The results showed that: (1) From the perspective of species composition, a total of 111 species were recorded in 20 sample plots with a total area of 2,000 m 2, belonging to 54 genera and 96 genera. The species number decreased from the forest margin to the forest. (2) From the perspective of community structure, the average DBH of arbor layer decreased from forest edge to forest, but the average density was opposite. The average height of shrub layer decreased from forest margin to forest, and the average height No significant change; the average density and average height of the herb layer showed a decreasing trend. (3) In terms of species diversity, the overall abundance index and Shannon-Wiener index at all levels decreased from the forest margin to the forest, and the shrub layer and herb layer showed the most obvious trend. At the same time, The common species and similarity coefficient between gradient and gradient 1 (forest margin) decreased from forest margin to forest. (4) It is found that the change of the values of average height, average density and similarity coefficient of each community feature is most obvious when the transition from Gradient 2 to Gradient 3, and it is inferred that the edge depth of the Cryptomeria fortunei plantation patch in this study is up to Inside the forest 20 m.