天目山自然保护区常绿落叶阔叶林优势种群空间分布格局

基于浙江省天目山常绿阔叶林1 hm²样地调查数据,应用点格局方法分析了3种优势种细叶青冈(Cyclobalanopsis gracilis)、杉木(Cryptomeria fortunei)、短尾柯(Lithocarpus brevicaudatus)的空间分布格局,对比了优势种不同生长阶段(幼苗、幼树、中树、大树)的空间分布格局以及不同生长阶段之间的空间关联性.结果表明:(1)3个主要优势种并未受到明显的生境异质性的影响,总体呈现随机分布格局,其中短尾柯由于具有较高的根蘖率,导致在中树种群阶段于2~10 m处呈现聚集分布;(2)3个主要优势种在不同生长阶段之间1~25 m尺度范围内总体表现为无关联性,其中幼树与幼苗在小尺度(1~3 m)上均表现为正相关,细叶青冈中树与大树阶段之间存在潜在的负相关趋势,杉木幼树与大树阶段存在潜在的正相关趋势;(3)3个优势种群在发育过程中均未明显受到密度制约造成的自疏效应的影响.

Dominant species populations and their spatial patterns in evergreen and deciduous broad-leaved forest in Tianmu Mountain,China

Population structure and spatial pattern are important characteristics of plant community which can reveal ecological characteristics of a species.In this study,we established a 1hm2 plot in subtropical evergreen broadleaved forest in the Tianmu Mountain National Nature Reserve,China.All trees with a diameter at breast height of at least 1cm were mapped and identified.Point pattern analysis was applied to analyze the tree spatial distribution patterns and spatial associations of the dominant species at different growth stages（i.e.seedling,young,middle and mature trees stage）.The three dominant species are Cyclobalanopsis gracilis,Cryptomeria fortunei and Lithocarpus brevicaudatus.Results show that the three dominant species show a random distribution pattern at different environmental heterogeneity.However,Lithocarpus brevicaudatus under middle stage appeares an aggregate distribution pattern at 2-10mscale due to high rate of tillers.In addition,three dominant species have no interspecific association in different growth stages at 1-25mscale.The saplings and seedlings show positive correlation,and the middle and mature trees of Cyclobalanopsis gracilis have potentially negative correlation at 1-3mscale.Moreover,young and mature trees of Cryptomeria fortunei have a potential positive correlation.Three dominant species have not been clearly influenced by the density dependence effect in the process of growth.