恩施州不同海拔马尾松天然次生林林分结构特征研究

Structure Characteristics of Pinus massoniana Natural Secondary Forest at Different Altitude of Enshi

  • 摘要: 以恩施州不同海拔马尾松天然次生林为研究对象,根据海拔梯度设置湖北民族学院后山(T1)、恩施市莲花池村(T2)、恩施市吉心村(T3)、利川市毛家院子(T4)4个样地,每个海拔梯度地点用全站仪建立4块20 m×20 m固定监测样地,分别对每块样地展开调查,分析其树种组成、胸径结构等非空间结构和角尺度、混交度、大小比等空间结构特征。结果表明:不同海拔马尾松天然次生林多为小径阶林木,天然更新状况良好,胸径分布宽度与海拔呈极显著正相关关系;林分的平均角尺度随着海拔的上升趋于随机分布,其中T1至T3的林分中,海拔与角尺度呈极显著正相关关系;不同海拔的各林分平均混交度普遍处于弱度混交和中度混交之间,其中T2至T4的马尾松天然次生林林分中,海拔与混交度呈极显著正相关关系;各林分整体平均大小比数在0.5左右,其中T2至T4的林分海拔与大小比数呈极显著正相关关系;随着海拔的升高,天然次生林中马尾松、杉木和柏木等针叶树种成为主要优势种。

     

    Abstract: The Pinus massoniana natural secondary forests of different altitudes in the state of Enshi from different altitudes were taken as the research objects, and the upper limit exclusion method was chosen to set up 4 elevation gradients:the behind the mountain of Hubei institute of nationalities (T1), Lotus pond village in Enshi City (T2), Jixin village in Enshi City (T3), Mao Jia yard in Lichuan City (T4), 4 stands of 20 m×20 m were bulit at each elevation gradient using total station instrument. The stand structure characteristics were investigated in each plot and the collected data were analyzed using spatial structure and non-spatial structure indicators such as uniform angle index, mingling index, neighborhood comparison, species composition and diameter distribution. Results show that there are many small diameter classes trees in the P. massoniana natural secondary forest from different altitudes, and exhibit good natural regeneration. The width of the diameter distribution is highly significant positively correlated with the elevation height. The average uniform angle indices of different forests are tending to be distributed randomly as the altitude rises, which is in a middle state. From T1 to T3, there is a highly significant positive correlation between the elevation and the uniform angle indices of the different forest stands. The average mingling of each forest at different altitude is low in general, and is between weak mixed and moderate mixed degree. The relationship between the elevation and mingling is highly significant positively correlated of the P. massoniana natural secondary forest stands from the altitude T2 to T4. The overall average neighborhood comparison of each forest is about 0.5, which is in a middle state. From T2 to T4, there is a highly significant positive correlation between the elevation and the neighborhood comparison of the different forest stands. As the altitude rises, the coniferous trees of natural secondary forests such as P. massoniana, Cunninghamia lanceolata and Cupressus funebris become the dominant species.

     

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