宁夏六盘山华北落叶松人工林...碳密度时空特征及其环境响应_张紫优.pdf

doi：10.11707/j.1001-7488.LYKX20230037宁夏六盘山华北落叶松人工林植被碳密度时空特征及其环境响应*张紫优1,2王彦辉2田奥2,3刘泽彬2郭建斌1于澎涛2王晓2于艺鹏2（1.北京林业大学水土保持学院北京 100083；2.中国林业科学研究院森林生态环境与自然保护研究所国家林业和草原局森林生态环境重点实验室北京 100091；3.贵州省山地资源研究所贵阳 550001）摘要：【目的】调查分析宁夏南部六盘山区华北落叶松人工林乔木层、灌木层和草本层碳密度大小及其时空变化规律，建立考虑立地环境和林分结构等主要因子影响的碳密度模型，为我国西北山区复杂地形条件下人工林碳密度估算和可持续经营提供理论基础和决策工具。【方法】采用样地清查与数学模型相结合的方法确定研究区华北落叶松人工林乔木层和林下灌草层碳密度；应用外包线法确定各植被层碳密度对各主要因子（林龄、林分密度、年均降水量、年均气温和坡向）的响应规律及其函数形式，通过连乘耦合构建反映多因子综合影响的植被碳密度模型，并基于实测数据进行模型率定和检验。【结果】1）六盘山区华北落叶松人工林植被碳密度平均为 46.82 thm2，其中乔木层占94.92%，灌木层和草本层分别占 4.76%和 0.32%。2）乔木层碳密度随林龄、林分密度、年均降水量增大先快速增加、超过阈值后缓慢增加并渐趋最大值，相应阈值为林龄 30 年、林分密度 1 500 株hm2、年均降水量 525 mm；随年均气温增加先增后减，6 时达到峰值；随坡向增大（正北为 0，随向两侧偏离正北方向的角度而增大）呈近线性降低。3）林下灌草层碳密度随乔木层碳密度增加近线性减少，随年均气温、年均降水量和坡向的变化规律与乔木层相同，相应阈值同样为年均气温 6、年均降水量 525 mm。4）多因子耦合模型可较好估算乔木层和林下灌草层碳密度变化，其 R2分别为0.8 和 0.7。5）根据模型模拟结果，华北落叶松人工林植被碳密度随海拔升高先增后降，垂直差异较大，最高分布范围在海拔 2 2002 400 m 之间；受地形和气候影响表现出一定的水平差异，西高东低、南高北低；阴坡植被碳密度高于阳坡，其中乔木层相差约 20%，灌草层相差可达 1 倍。【结论】宁夏六盘山华北落叶松人工林植被碳密度平均为 46.82 thm2，以乔木层为主，受立地环境（年均降水量、年均气温、坡向）和林分结构（林龄、林分密度）的多因子综合影响，林下灌草层碳密度受乔木层生物量影响，应用多因子耦合模型可较好解释并预测其时空变化；合理选择造林立地类型和林分密度有利于维持较好的华北落叶松林植被碳密度和层次组成。关键词：华北落叶松人工林；植被层；碳密度；耦合模型；宁夏六盘山中图分类号：Q958.15;S154.5文献标识码：A文章编号：10017488(2023)04003214Spatiotemporal Characteristics and Environmental Response of Vegetation Carbon Densities ofLarix principis-rupprechtii Plantations in the Liupan Mountains of Ningxia,ChinaZhang Ziyou1,2Wang Yanhui2Tian Ao2,3Liu Zebin2Guo Jianbin1Yu Pengtao2Wang Xiao2Yu Yipeng2（1.College of Soil and Water Conservation,Beijing Forestry UniversityBeijing 100083；2.Key Laboratory of Forestry Ecology and Environment of NationalForestry and Grassland AdministrationEcology and Nature Conservation Institute,Chinese Academy of ForestryBeijing 100091；3.Institute of MountainResource of Guizhou ProvinceGuiyang 550001）Abstract：【Objective】In this study,the spatiotemporal variation of vegetation carbon densities(VCD)of the tree layer,understory shrub layer and herb layer of larch(Larix principis-rupprechtii)plantations in the Liupan Mountains area of southernNingxia of northwest China were investigated and analyzed,and the VCD models considering the effects of multiple factors of sitequality and stand structure were established,so as to provide theoretical basis and decision-making tools for estimating VCD andtheir sustainable management of the larch plantations under complex topographic conditions in the mountainous regions ofnorthwest China.【Method】The VCD of tree,shrub and herb layers of larch plantations in the study area was determined by thecombined application of sample plot inventory and mathematical models.The upper boundary line method was used to determinethe response pattern and corresponding function form of VCD to each main influencing factor(forest age,density,mean annual 收稿日期：20230201；修回日期：20230228。基金项目：国家重点研发计划项目（2022YFF1300404，2022YFF0801803）；国家自然科学基金项目（U20A2085，U21A2005，42161144008，32271959）。*郭建斌为通讯作者。第 59 卷 第 4 期林业科学 Vol.59，No.42 0 2 3 年 4 月SCIENTIA SILVAE SINICAEApr.，2 0 2 3precipitation,mean annual air temperature,slope aspect).A VCD model that can reflect the comprehensive impact of multiplefactors was constructed through multiplicative coupling,and then the measured data were used to calibrate and validate the model.【Result】1)The average VCD of the existing larch plantations in the Liupan Mountains area was 46.82 t Chm-2,of which thetree layer accounted for 94.92%,while the shrub layer and herb layer only accounted for 4.76%and 0.32%,respectively.2)TheVCD of tree layer firstly increased rapidly with the increase of forest age,stand density,and mean annual precipitation,and thenincreased slowly and gradually tended to its maximum value after exceeding the certain threshold values of those factors.Thecorresponding threshold values for those influencing factors were 30 years of forest age,1500 treehm-2 of tree density,and 525mm of mean annual precipitation.The VCD of tree layer firstly increased and then decreased with rising mean annual temperatureand reached its peak at 6C.It decreased nearly linearly with rising slope aspect(0 to due north,increasing with the deviationangle from north direction to both sides).3)The VCD of the understory shrub-herb layers decreased linearly with rising tree layerVCD,and varied with mean annual temperature and precipitation as well as slope aspect in the same patterns of tree layer VCD andthe same threshold values of 6 C and 525 mm.4)The established multi-factor coupled model of VCD was able to better estimatethe variation of VCD of tree layer and understory shrub-herb layer,with R2 of 0.8*and 0.7*,respectively.(5)According tosimulation results of the model,the VCD of larch plantations firstly increased and then decreased with rising elevation,showing arelatively bigger difference among elevation gradients,the elevation range with the highest VCD was 22002400 m.Due to theeffects of topography and climatic factors,there existed a certain horizontal difference,namely decreasing from west to east andfrom south to no