| 北京油松人工林竞争指数的适用性评价 |
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| 引用本文： | 李超,裴顺祥,张连金,郭嘉,辛学兵.北京油松人工林竞争指数的适用性评价[J].浙江农林大学学报,2019,36(6):1115-1124. |
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| 作者姓名： | 李超 裴顺祥 张连金 郭嘉 辛学兵 |
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| 作者单位： | 中国林业科学研究院 华北林业实验中心, 北京 102300 |
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| 基金项目： | "十三五"国家重点研发计划项目2016YFD060020304 |
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| 摘 要： | 为筛选北京油松Pinus tabulaeformis人工林的最适竞争指数，获取油松人工林科学经营管理的依据和理论支撑，以九龙山油松人工林内的1 054株油松对象木及4 216株竞争木为研究对象，通过Hegyi竞争指数、Bella竞争指数（CIOi）及基于交角的林木竞争指数（d_α_CIi）进行生物量回归分析和k折交叉验证，筛选并分析油松人工林的最适竞争指数。结果显示:油松的径级分布呈略正偏的正态分布，88.24%的个体分布在10~25 cm径级内；油松生物量与d_α_CIi，Hegyi竞争指数服从幂函数关系，CIOi服从指数函数关系。d_α_CIi与油松生物量的决定系数（R2）、10次10折交叉验证R2值均最高，R2损失量最小，量化效果最好；Hegyi竞争指数次之，CIOi最差，说明d_α_CIi是量化北京典型油松人工林竞争强度的最佳指标。林木竞争受数量、大小和物种共同影响。随着油松对象木胸径的增大，竞争指数逐渐减小，其上方遮盖所占竞争指数比例也逐渐降低，甚至没有。当油松胸径不小于20 cm时（约总体前1/4），随径级增大其竞争指数变化不显著；据此对油松胸径小于20 cm的个体进行合理抚育间伐，能改善油松林结构。油松所受竞争主要来自种内，占总竞争强度的93.64%，种内竞争木数量、竞争强度随径级呈先增大后减小的趋势，而种间竞争木数量、竞争强度随径级总体上呈先减小后增大趋势，表明种内竞争大于种间及两者间的垂直空间分离是物种共存的重要条件。
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| 关 键 词： | 森林经理学 竞争指数 筛选 k折交叉检验 油松 |
| 收稿时间： | 2018-12-12 |
Applicability evaluation of competition indexes for Pinus tabuliformis plantations in Beijing |
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| LI Chao,PEI Shunxiang,ZHANG Lianjin,GUO Jia,XIN Xuebing.Applicability evaluation of competition indexes for Pinus tabuliformis plantations in Beijing[J].Journal of Zhejiang A&F University,2019,36(6):1115-1124. |
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| Authors: | LI Chao PEI Shunxiang ZHANG Lianjin GUO Jia XIN Xuebing |
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| Affiliation: | Forestry Experiment Center of North China, Chinese Academy of Forestry, Beijing 102300, China |
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| Abstract: | Due to poor management, the competition intensity of Pinus tabuliformis plantations of Beijing region are generally strong, which leads to low stand quality. Therefore, scientific management is urgently needed to improve stand competition and stand quality. To provide a basis and theoretical support for scientific management of P. tabuliformis plantations in the Beijing region, an optimal competition index was determined from typical P. tabuliformis plantations in Beijing. A 100 m×100 m sample plot of typical P. tabuliformis plantation was set up in Jiulong Mountains, with 1 054 P. tabuliformis objective trees and 4 216 competitive trees in the sample plot as the research objects. A biomass regression analysis was used with competition indexes of Hegyi, CIOi, and angle-based (d_α_CIi). The optimum competitive index was selected by regression analysis and k-fold cross-validation; Kruskal-Wallis test was used to analyze the competition index of P. tabuliformis with different diameter at breast height (DBH) class size in the sample plot. Results showed that the diameter distribution of P. tabuliformis had a slightly positive normal distribution with 88.24% of the individuals distributed in the 10-25 cm diameter range. P. tabuliformis biomass obeyed the power function relation with (d_α_CIi) and Hegyi competition indexes, and obeyed the exponential function relation with CIOi. The coefficient of determination (R2), and 10 times of 10-fold cross-validation R2 values of (d_α_CIi) were highest (R2 is 0.770 5 and 0.769 5, respectively), and the loss of R2 was smallest (R2=0.001 0) meaning the quantization effect was (d_α_CIi) > Hegyi > CIOi. The competition index gradually decreased with an increase in DBH, and the proportion of over shading of the competition index also gradually decreased or stayed the same. When DBH was not less than 20 cm (about 1/4 of the total), the change in competition index did not vary (P>0.05)with an increase in class size. Competition was mainly intraspecific accounting for 93.64% of the total competition intensity. The quantity and competition intensity of intraspecific competition trees increased first and then decreased with diameter class. However, on the whole, the number and competition intensity of interspecific competition trees decreased first and then increased with the diameter class. Thus, (d_α_CIi) could better quantify competition intensity of typical P. tabuliformis plantations in Beijing; intraspecific competition was greater than interspecific competition with vertical spatial segregation within and between species being important conditions for species coexistence; and according to the spatial distribution of competition indexes for P. tabuliformis, reasonable thinning of individuals with a DBH less than 20 cm could improve forest structure. |
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