南亚热带马尾松人工林近自然恢复过程中林下木本植物生态位动态

Niche Dynamics of Understory Woody Plants During the Nearnatural Restoration of Pinus massoniana Plantations in Southern Subtropics

为了解广西南亚热带近自然恢复过程中马尾松Pinus massoniana人工林林下主要木本植物的生态位动态变化特征,以“空间代替时间”的方法,在群落学调查的基础上采用Levins生态位宽度指数和Pianka生态位重叠指数对马尾松人工林亚乔木层和灌木层木本植物种群生态位进行定量分析。结果表明:(1)马尾松中龄林亚乔木层的山乌桕Sapium discolor、灌木层的鹅掌柴Schefflera heptaphylla,成熟林亚乔木层的狭基润楠Machilus attenuata、灌木层的三桠苦Evodia lepta,以及过熟林亚乔木层的鹅掌柴、灌木层的纽子果Ardisia palysticta生态位宽度较大,在各自群落中属于优势种群;(2)重要值越大的物种通常生态位宽度越大,但是二者之间的排序并不完全相同,生态位宽度与生态位重叠之间无显著的正相关关系;(3)随着马尾松人工林从中龄林到成熟林到过熟林近自然恢复的进行,亚乔木层物种间生态位分化程度增加,生态位重叠程度逐渐下降,灌木层物种受到可利用资源和自身生物学特性的限制,物种间生态位分化不明显,生态位重叠程度增加,马尾松人工林群落中亚乔木层较灌木层有更高的稳定性。

In order to understand the dynamic changes of the niche characteristics of the main woody plants under the Pinus massoniana plantations of near-natural recovery in southern subtropical of Guangxi,based on community survey,the method of"space instead of time",the Levins niche breadth index and the Pianka niche overlap index were used to quantitatively analyze the niche of wood plant populations in the understory trees and shrub layer of P.massoniana plantations.The results showed that Sapium discolor in the understory trees and Schefflera heptaphylla in the shrub layer of the middle-aged P.massoniana plantations,Machilus attenuate in the understory trees and Evodia lepta in the shrub layer of mature P.massoniana plantations,S.heptaphylla in the understory trees and Ardisia palysticta in the shrub layer of the overripe P.massoniana plantations,exhibited larger niche breath and belonged to the dominant population in their respective communities.Species with greater importance value generally had larger niche breadth,but the order between the two was not exactly the same,and there was no significant positive correlation between niche breadth and niche overlap.With the advancing of near-natural restoration in P.massoniana plantations from middle-aged forest to mature forest to overripe forest,the degree of niche differentiation among species in the understory trees increased,while the degree of niche overlap gradually decreased.Species in the shrub layer were limited by available resources and their own biological characteristics,and the niche differentiation among species was not obvious and the degree of niche overlap increased.The understory trees in P.massoniana plantations communities had higher stability than the shrub layer.