丹江口湖北库区不同调控密度马尾松人工林林分特征

The Stand Features of Pinus massoniana Plantation with Different Regulation Density in Danjiangkou Reservoir Area of Hubei Province

以丹江口湖北库区马尾松人工林为研究对象,从林分结构、天然更新演替和生物多样性等方面探讨不同调控密度的林分特征。结果表明,林分密度的降低有利于乔木层平均树高、平均胸径、优势高、枝下高的明显增加,不同调控密度林分高度分布整体均呈现正态分布曲线,但不同密度林分其峰值波动范围的宽窄程度各不相同,低密度林分高度结构更趋于完整;高密度林分立木胸径以小径阶为主,低中密度林分大径阶立木数量则明显增加。高中低密度马尾松林下更新树种种类分别为5种、7种和8种,均以栓皮栎和盐肤木构成其优势更新树种;随着林分密度的增加,更新幼苗数量以及更新层优势种幼树幼苗与乔木树种数量之比均表现为逐渐降低趋势,且更新幼苗多集中在高度≥50 cm范围。马尾松林分密度的降低均在一定程度上促进林下生物多样性的增加,但不同层次生物多样性变化趋势存在差异。

A Pinus massoniana plantation of Danjiangkou reservoir of Hubei Province was selected as object to analyze the stand features under different regulation density from three respects of the stand structure,natural re-generation status and biodiversity.The results showed that average tree height,average DBH,dominant height,and under branch height were significantly increased with the stand density decreased.At the same time,the height dis-tribution in three densities of Pinus massoniana plantation all showed a normal distribution curve,but the stand height structure at low density tended to be more complete.In high density stand,small diameter class trees were main components,but in low-medium density stand,the number of larger diameter tree was increased significantly. The number of regeneration species under forest of high density,medium density and low density P.massoniana were 5,7 and 8,respectively,and the dominant regeneration species were Quercus variabilis and Rhus chinensis. With the stand density increased,the number of regeneration seedlings,the ratio of saplings and seedlings to domi-nant trees gradually decreased.The seeding characteristic was more concentrated in height≥50 cm,and the stand was lack of low age old seedlings.The density decrease of Pinus massoniana stand promoted the increase of biologi-cal diversity of understory vegetation in some extent,but there were some differences on the variation trends of bio-logical diversity between different layers.