摘要
本研究以东北林业大学帽儿山实验林场55块长白落叶松人工林固定样地调查数据为基础,采用均值±标准差法将林分密度指数(SDI)划分为3个等级,即SDI Ⅰ∈(0,695]、SDI Ⅱ∈(695,1027]、SDI Ⅲ∈(1027,∞]株·hm^(-2);以Logistic方程为基础,耦合哑变量和分位数回归构建不同SDI等级下的3个分位点处(0.90、0.95和0.99)的单木最大冠幅预测模型,进而采用树冠投影面积法编制不同SDI等级下的林分经营密度数表,探讨林分密度对蓄积量和碳储量的影响。结果表明:不同SDI的单木最大冠幅模型具有显著差异,且均以0.90分位点能够更好地模拟单木最大冠幅;独立样本检验表明,与Logistic基础模型相比,单木哑变量分位数最大冠幅模型的R_(adj)^(2)可显著提高0.20,而均方根误差显著降低0.15 m。基于建立的单木哑变量分位数最大冠幅模型和树冠投影面积法,编制出了不同SDI等级下的林分经营密度数表;当培育目标直径为30 cm时,与SDI Ⅰ相比,不区分SDI等级时相应的林分蓄积量和碳储量分别被高估26.16 m^(3)·hm^(-2)和10.10 t C·hm^(-2);与SDI Ⅱ相比,其同样被高估15.99 m^(3)·hm^(-2)和6.12 t C·hm^(-2);但与SDI Ⅲ相比,其被显著低估85.13 m^(3)·hm^(-2)和33.04 t C·hm^(-2),表明忽略SDI等级差异会系统性高估低密度林分的碳汇能力,同时低估高密度林分的实际贡献。因此,按SDI等级开展林分密度调控,有利于实现该地区长白落叶松人工林质量的精准提升。
Based on the survey data of 55 permanent plots of Larix olgensis plantation in Maoershan Experimental Forest Farm of Northeast Forestry University,we divided the stand density index(SDI)of the plots into three grades by mean±standard deviation method,namely SDIⅠ∈(0,695],SDIⅡ∈(695,1027],and SDIⅢ∈(1027,∞]trees·hm^(-2).Based on the Logistic equation,we constructed the maximum crown width prediction model of individual tree at three quantiles(0.90,0.95,and 0.99)under different SDI grades by coupling dummy variables and quantile regression.We further used the crown projection area method to compile the stand management density number table under different SDI grades and quantified the influence of stand density on stand volume and carbon storage.The results showed that the maximum crown width models of individual tree with different SDI had significant differences,and that the maximum crown width of individual tree could be better simulated at 0.90 quantile.The independent sample test showed that compared with the Logistic basic model,the R_(adj)^(2) of the single-tree dummy variable quantile maximum crown model could be significantly increased by 0.20,while the root mean square error was significantly reduced by 0.15 m.Based on the established single tree dummy variable quantile maximum crown width model and crown projection area method,we compiled the stand management density number table under different SDI grades.When the target diameter of cultivation was 30 cm,compared with SDIⅠ,stand volume and carbon storage were overestimated by 26.16 m^(3)·hm^(-2) and 10.10 t C·hm^(-2),respectively,when SDI grades were not distinguished.Similarly,compared with SDIⅡ,these values were overestimated by 15.99 m^(3)·hm^(-2) and 6.12 t C·hm^(-2).However,compared with SDIⅢ,they were significantly underestimated by 85.13 m^(3)·hm^(-2) and 33.04 t C·hm^(-2).Our results indicated that ignoring the differences of SDI grades could overestimate the carbon sequestration capacity of low-density stands but underestimate the actual contribution of high-density stands.Therefore,implementing stand density regulation based on SDI grades is conducive to achieving precise quality improvement of L.olgensis plantations.
作者
张薇
陈冠谋
董灵波
ZHANG Wei;CHEN Guanmou;DONG Lingbo(Ministry of Education Key Laboratory of Sustainable Forest Ecosystem Management,School of Forestry,Northeast Forestry University,Harbin 150040,China)
出处
《应用生态学报》
北大核心
2025年第8期2270-2278,共9页
Chinese Journal of Applied Ecology
基金
国家自然科学基金项目(32171778)资助。
关键词
长白落叶松
分位数回归
冠幅模型
林分经营密度数表
Larix olgensis
quantile regression
crown width model
stand management density number table
