Ecosystem service multifunctionality of mixed conifer-broad-leaved forests under climate change and forest management based on matrix growth modelling

Climate change and forest management are recognized as pivotal factors influencing forest ecosystem services and thus multifunctionality.However,the magnitude and the relative importance of climate change and forest management effects on the multifunctionality remain unclear,especially for natural mixed forests.In this study,our objective is to address this gap by utilizing simulations of climate-sensitive transition matrix growth models based on national forest inventory plot data.We evaluated the effects of seven management scenarios(combinations of various cutting methods and intensities)on the future provision of ecosystem services and multifunctionality in mixed conifer-broad-leaved forests in northeastern China,under four climate scenarios(SSP1-2.6,SSP2-4.5,SSP5-8.5,and constant climate).Provisioning,regulating,cultural,and supporting services were described by timber production,carbon storage,carbon sequestration,tree species diversity,deadwood volume,and the number of large living trees.Our findings indicated that timber production was significantly influenced by management scenarios,while tree species diversity,deadwood volume,and large living trees were impacted by both climate and management separately.Carbon storage and sequestration were notably influenced by both management and the interaction of climate and management.These findings emphasized the profound impact of forest management on ecosystem services,outweighing that of climate scenarios alone.We found no single management scenario maximized all six ecosystem service indicators.The upper story thinning by 5%intensity with 5-year interval(UST5)management strategy emerged with the highest multifunctionality,surpassing the lowest values by more than 20%across all climate scenarios.In conclusion,our results underlined the potential of climate-sensitive transition matrix growth models as a decision support tool and provided recommendations for long-term strategies for multifunctional forest management under future climate change context.Ecosystem services and multifunctionality of forests could be enhanced by implementing appropriate management measures amidst a changing climate.

Carbon Dynamics in Woody Biomass of Forest Ecosystem in China with Forest Management Practices under Future Climate Change and Rising CO_2 Concentration

It is critical to study how different forest management practices affect forest carbon sequestration under global climate change regime. Previous researches focused on the stand-level forest carbon sequestration with rare investigation of forest carbon stocks influ- enced by forest management practices and climate change at regional scale. In this study, a general integrative approach was used to simulate spatial and temporal variations of woody biomass and harvested biomass of forest in China during the 21st century under dif- ferent scenarios of climate and CO2 concentration changes and management tasks by coupling Integrated Terrestrial Ecosystem Carbon budget （InTEC） model with Global Forest Model （G4M）. The results showed that forest management practices have more predominant effects on forest stem stocking biomass than climate and CO2 concentration change. Meanwhile, the concurrent future changes in cli- mate and CO2 concentration will enhance the amounts of stem stocking biomass in forests of China by 12%-23% during 2001-2100 relative to that with climate change only. The task for maximizing stem stocking biomass will dramatically enhance the stem stocking biomass from 2001~100, while the task for maximum average increment will result in an increment of stem stocking biomass before 2050 then decline. The difference of woody biomass responding to forest management tasks was owing to the current age structure of forests in China. Meanwhile, the sensitivity of long-term woody biomass to management practices for different forest types （coniferous forest, mixed forest and deciduous forest） under changing climate and CO2 concentration was also analyzed. In addition, longer rotation length under future climate change and rising CO2 concentration scenario will dramatically increase the woody biomass of China during 2001~100. Therefore, our estimation indicated that taking the role of forest management in the carbon cycle into the consideration at regional or national level is very important to project the forest carbon sequestration under future climate change and rising atmospheric CO2 concentration.

Reliability model of organization management chain of South-to-North Water Diversion Project during construction period

In order to analyze the indispensability of the organization management chain of the South-to-North Water Diversion Project （SNWDP）, two basic forms （series connection state and mixed state of both series connection and parallel connection） of the organization management chain can be abstracted. The indispensability of each form has been studied and is described in this paper. Through analysis of the reliability of the two basic forms, reliability models of the organization management chain in the series connection state and the mixed state of both series connection and parallel connection have been set up.

Genetic Worth Effect Models for Boreal Conifers and Their Utility When Integrated into Density Management Decision-Support Systems

Based on approaches deduced from previous research findings and empirical observations from density control experiments, genetic worth effect response models were developed for black spruce (Picea mariana (Mill) BSP.) and jack pine (Pinus banksiana Lamb.) plantations. The models accounted for the increased rate of stand development arising from the planting of genetically-improved stock through temporal adjustments to the species-specific site-based mean dominant height-age functions. The models utilized a relative height growth modifier based on known estimates of genetic gain. The models also incorporated a phenotypic juvenile age-mature age correlation function in order to account for the intrinsic temporal decline in the magnitude of genetic worth effects throughout the rotation. Integrating the functions into algorithmic variants of structural stand density management models produced stand development patterns that were consistent with axioms of even-aged stand dynamics.

Practice of Perioperative Rational Use of Antibacterial Drugs Based on Drug Pathway

[Objectives]To establish a new management model for rational use of perioperative antibacterial drugs in surgical departments.[Methods]Based on evidence-based medicine,the department s drug pathway was formulated,and the new mode of rational drug use control was established by using fine pharmaceutical technology intervention,and the intervention effect was evaluated by the intensity of antibacterial drug use,per capita drug costs and the proportion of drugs.[Results]After adopting drug pathway in departments,the intensity of antibacterial drug use,per capita drug costs and the proportion of drugs decreased significantly,and the effect of rational drug use control was remarkable.[Conclusions]The drug pathway provides a new management and control mode for the rational use of perioperative antibacterial drugs in surgical departments of hospitals.Thus,it is worthy of popularization and application.

Generalized Height-Diameter Models for Pinus montezumae Lamb. and Pinus pseudostrobus Lindl. Plantations in Michoacan, Mexico

Tree height (H) in a natural stand or forest plantation is a fundamental variable in management, and the use of mathematical expressions that estimate H as a function of diameter at breast height (d) or variables at the stand level is a valuable support tool in forest inventories. The objective was to fit and propose a generalized H-d model for Pinus montezumae and Pinus pseudostrobus established in forest plantations of Nuevo San Juan Parangaricutiro, Michoacan, Mexico. Using nonlinear least squares (NLS), 10 generalized H-d models were fitted to 883 and 1226 pairs of H-d data from Pinus montezumae and Pinus pseudostrobus, respectively. The best model was refitted with the maximum likelihood mixed effects model (MEM) approach by including the site as a classification variable and a known variance structure. The Wang and Tang equation was selected as the best model with NLS;the MEM with an additive effect on two of its parameters and an exponential variance function improved the fit statistics for Pinus montezumae and Pinus pseudostrobus, respectively. The model validation showed equality of means among the estimates for both species and an independent subsample. The calibration of the MEM at the plot level was efficient and might increase the applicability of these results. The inclusion of dominant height in the MEM approach helped to reduce bias in the estimates and also to better explain the variability among plots.

A basal area increment model for individual trees in mixed continuous cover forests in Iranian Caspian forests

The aim of this study was to develop and test a new basal area growth model in mixed species continuous cover forests in northern Iran.Weanalyzed 421 core samples from 6 main species in the forest area to develop our growth model.In each plot,we measured variables such as total tree height(m),diameter at breast height(DBH)(cm)and basal area of larger trees as cumulative basal areas of trees(GCUM)ofDBH[5 cm.The empirical data were analyzed using regression analysis.There was a statistically significant nonlinear function between the annual basal area increment,as the dependent variable,and the basal area of the individual trees and competition as explanatory variables.Reference area from the largest trees,was circular plot with area of 0.1 ha.GCUM was estimated for trees of DBH>5 cm.Furthermore,we investigated the dependencies of diameter growth of different species on stand density at different levels of competition,and diameter development of individual trees through time.The results indicate that competition caused by larger neighborhood trees has a negative effect on growth.In addition,the maximum diameter increment is affected by competition level.Therefore,the maximum diameter increment of species occurs when the trees are about 35–40 cm in dense-forest(40 to 0 m^2 per ha)and when the trees are about 60 to 70 cm in very dense forest(60 to 0 m^2 per ha)which is more likely to Caspian natural forests with high level density due to uneven-aged composition of stands.

Bridging mapping and simulation modelling in the ecosystem service assessments of boreal forests:effects of bioenergy production on carbon dynamics

Background:Increasing the use of forest harvest residues for bioenergy production reduces greenhouse emissions from the use of fossil fuels.However,it may also reduce carbon stocks and habitats for deadwood dependent species.Consequently,simple tools for assessing the trade-offs of alternative management practices on forest dynamics and their services to people are needed.The objectives of this study were to combine mapping and simulation modelling to investigate the effects of forest management on ecosystem services related to carbon cycle in the case of bioenergy production;and to evaluate the suitability of this approach for assessing ecosystem services at the landscape level.Stand level simulations of forest growth and carbon budget were combined with extensive multi-source forest inventory data across a southern boreal landscape in Finland.Stochastic changes in the stand age class distribution over the study region were simulated to mimic variation in management regimes.Results:The mapping framework produced reasonable estimates of the effects of forest management on a set of key ecosystem service indicators:the annual carbon stocks and fluxes of forest biomass and soil,timber and energy-wood production and the coarse woody litter production over a simulation period 2012–2100.Regular harvesting,affecting the stand age class distribution,was a key driver of the carbon stock changes at a landscape level.Extracting forest harvest residues in the final felling caused carbon loss from litter and soil,particularly with combined aboveground residue and stump harvesting.It also reduced the annual coarse woody litter production,demonstrating negative impacts on deadwood abundance and,consequently,forest biodiversity.Conclusions:The refined mapping framework was suitable for assessing ecosystem services at the landscape level.The procedure contributes to bridging the gap between ecosystem service mapping and detailed simulation modelling in boreal forests.It allows for visualizing ecosystem services as fine resolution maps to support sustainable land use planning.In the future,more detailed models and a wider variety of ecosystem service indicators could be added to develop the method.

Use of Logistic Regression Model for Prediction of Non-Timber Forest Products

The use of non-timber is a valuable alternative for the conservation of tropical forests. Juçara (Euterpe edulis Mart.) is considered one of the main alternatives in the Atlantic Forest for the production of açaí pulp. However, there are few studies that aim to evaluate their production. The present study aimed to construct a probabilistic model to predict the production of Euterpe edulis bunches, using dendrometric variables and competition index. Twenty plots of 10 × 50 m were sampled in an area with said specie, showing the arboreal entities with diameter at breast height > 4.8 cm, and recording the Euterpe edulis phenomena. The main variables influencing the production of bunches were assessed using logistic regression model. The logistic regression showed the variables diameter breast height (DBH) and total height (h) as significant to explain the variation between productive and non-productive entities. The competition index tested was not significant (p-value = 0.221). The model of prediction of curl production in Juçara can be written as: Zi = -6.878594 + 0.2522454 × DBH + 0.1951574 × h. The use of a logistic regression model showed potential for prediction of non-timber forest products.

长白山主要林分物种多度分布与性状分布的关系

【目的】探究长白山地区群落物种的多度分布格局及其驱动过程,以及多度分布与性状分布之间的关系,为当地森林经营与修复策略的制定提供理论依据。【方法】以长白山不同林分类型的3块5.2 hm2(次生山杨白桦林、次生针阔混交林、原始红松紫椴林)和1块5 hm2原始阔叶红松林固定监测样地为研究对象,通过采集样地内木本个体的6个关键功能性状(叶面积、比叶面积、叶片厚度、最大树高、叶片氮含量、叶片磷含量),分析样地的物种多度分布格局、功能性状分布格局以及二者之间的关系。【结果】不同林分类型中通过统计检验的模型种类各异,但所有最优模型均为统计模型。在性状分布格局中,最大树高、比叶面积和叶磷含量在4块样地均呈现正态分布。然而,功能性状分布格局转化得到的物种分布格局模型显示,尽管部分模型通过了统计检验,但与多度分布结果拟合度不高。【结论】在长白山地区,物种多样性的形成并非主要由随机过程驱动,而是受到竞争作用的显著影响,这决定了演替过程中群落物种组成的变化情况。虽然功能性状分布与物种多度分布之间存在一定的联系,但直接通过群落水平性状分布格局推断物种多度的方法尚不准确。

精细化临床路径管理降低按疾病诊断相关组模式下妇科手术NC1-子宫手术病组费用的效果

目的探讨精细化临床路径管理在降低按疾病诊断相关组(DRG)模式下妇科手术NC1-子宫(除子宫腔内病变以外)手术病组费用的应用效果。方法选取2023年徐州市妇幼保健院因子宫病损行子宫切除术而纳入NC1-子宫手术病组的164例患者进行回顾性分析,其中2023年1月至4月未实施精细化临床路径管理的91例患者作为对照组,2023年7月至10月实施精细化临床路径管理的73例患者作为研究组。比较两组患者的住院费用、住院时间、治愈好转率等。结果两组患者治愈好转率和严重并发症发生率比较,差异无统计学意义(P>0.05);两组患者平均住院日和术前平均住院日比较,差异无统计学意义(P>0.05);两组患者次均综合医疗服务类费用和次均治疗类费用比较,差异无统计学意义(P>0.05)。研究组次均住院费用、次均药费、次均耗材费均低于对照组,差异有统计学意义(P<0.05)。结论通过精细化临床路径管理,在保障医疗安全的前提下,不以缩短住院时间、减少治疗费用为手段,而是通过合理使用药品耗材,能有效降低DRG模式下妇科手术NC1-子宫手术病组患者的住院费用,为患者提供高效优质的医疗服务。

农户分化对农户林地承包经营不履责行为的影响

依据2021年南方集体林区4个省400个样本农户的调查数据,分别采用Logit模型及中介效应模型研究农户分化对农户林地承包经营不履责行为的现实影响。研究表明:农户分化对农户林地承包不履责行为的发生及规模具有显著正向影响;高分化程度农户与较低分化程度农户相比,农户林地承包不履责行为受户主特征及林地特征因素影响更为显著;农户分化能够通过提高村内林业生产资本投资对农户林地承包经营不履责行为产生抑制性影响。故此,应在建立农户林地承包经营履责约束机制以及差异化激励机制以促进农户林地承包责任制落实的同时,通过强化引导和扩大林业资本投资的林业财政金融支持政策来抑制和克服农户分化对农户林地承包经营不履责行为的影响。

山西太岳山不同针叶纯林及混交林土壤有机碳库的变异性

为研究不同针叶林型土壤有机碳及其碳库管理指数变化特征,以山西太岳山林区油松(Pinus tabuliformis)林、华北落叶松(Larix gmelinii var.principis-rupprechtii)林、油松和华北落叶松混交林3种人工林为研究对象,测定了各森林群落的根系生物量、土壤理化性质,分析不同林型土壤理化性质及碳库管理指数的变化特征。结果表明:土壤有机碳质量分数、全氮质量分数、土壤含水率、β-葡萄糖苷酶活性、酸性磷酸酶活性等均在油松落叶松混交林中出现最大值。3种林型的土壤有机碳库中,稳定有机碳的质量分数最高,约占总有机碳的80%以上。在0<h≤10 cm土层中,油松林土壤碳库管理指数显著低于落叶松林和油松落叶松混交林(P<0.05),前者分别比后两者低22.32%、21.69%。相关性分析及结构方程模型(SEM)表明,林分类型的转变对土壤含水率、土壤酶活性有显著正向影响(P<0.05),根系生物量显著促进了土壤养分及土壤酶活性的增加,土壤养分及根系生物量对土壤碳库管理指数产生显著正向影响(P<0.05)。油松和华北落叶松混交可以提高土壤养分质量分数,增强土壤微生物活性,有利于土壤碳库管理指数和碳库质量的提高。

新型林业经营主体政策性森林保险需求的影响因素分析

采用6个省(自治区)15个县市485个新型林业经营主体样本实地调研的2015—2018年面板数据,对新型林业经营主体森林保险需求的影响因素进行实证分析。结果表明:受灾面积和受灾损失每增加1个单位,分别会引起新型林业经营主体对政策性森林保险的需求增加1.728个单位和1.704个单位;生产费用和家庭收入每增加1个单位,分别会引起新型林业经营主体对政策性森林保险的需求增加0.213个单位和0.052个单位;基础设施投入和财务费用投入每增加1个单位,分别导致新型林业经营主体对政策性森林保险的需求下降0.303个单位和0.05个单位。此外,进一步检验了经营规模对政策性森林保险需求的调节作用。针对研究结果,从进一步推动林业生产规模化、促进保险产品多样化、加大政府对森林保险的扶持等方面提出建议。

基于改进的王正非模型结合元胞自动机的林火蔓延预测

【目的】针对当前我国林火蔓延预测仍存在预测精度不高、普适性差等问题,基于王正非速度模型结合多维元胞自动机的林火蔓延预测模型进行改进,研究了不同区域和分辨率下该模型的有效性,增强了该模型对于不同分辨率数据的适应能力,从而更好地对森林火灾蔓延进行预测,并为林区的火灾蔓延预测和管理提供一种科学合理的技术手段。【方法】使用黑龙江省大兴安岭地区2011年10月28日发生的森林火灾(分辨率500 m)与四川省凉山地区2022年3月29日发生的森林火灾(分辨率30 m)作为数据源,提取发生火灾时刻以及蔓延过程的火线。引入归一化植被指数(NDVI)对王正非模型进行改进,并利用反卷积算法对元胞自动机算法进行改进,将改进后模型输出的结果与实际结果进行精度对比,并比较不同分辨率下的模型精度表现。【结果】改进后的模型精度有明显的提升,其中,黑龙江省大兴安岭试验改进后模型的kappa系数提高了0.0297,面积误差率降低了21.33%,火场预测火点170个,平均过火速度0.75 m/min。四川省木里县试验改进后模型的kappa系数提高了0.1165,面积误差率降低了37.08%,火场预测火点1795个,平均过火速度为4.00 m/min。【结论】改进后的林火蔓延预测模型可以更有效地预测火灾蔓延并计算出最可能过火的火点位置,其预测结果具有高度的一致性和准确性,提高了林火蔓延模拟预测的实用性。与原始模型相比,改进后的模型很好地提高了在不同分辨率数据下的预测精度,能为林火预防和管理提供科学依据。

基于农户受偿意愿的天然林管护补偿标准研究

全面停止天然林商业性采伐政策是维护森林资源与生态安全的有效手段,研究效用最大化条件下有效激励农户主动参与天然林管护的补偿标准对政策的进一步完善与推进具有重要的意义。基于陕西、辽宁、湖南、福建4省917份集体林区调研数据,从农户受偿意愿视角,利用非参数估计和参数估计2种方法,测算出政策参与后农户意愿投入禁伐天然林管护的补偿标准,并利用Logistics模型探讨农户天然林管护意愿的影响因素。结果表明,1)样本选区约有76.8%的农户愿意投入天然林管护,仍有进一步提升空间;2)非参数估计方法与参数估计计算结果存在一定的差值,2个补偿额度可作为天然林停伐管护补偿标准的动态调整区间。总体上看,参数估计与非参数估计得到农户的受偿意愿调整区间为0.12~0.18万元/hm^(2),但从不同省份结果看,呈现出“北高南低”的特征;3)农户天然林管护意愿受偿农户个体特征、农户家庭特征、林地经营特征、政策环境特征的共同影响。鉴于此,政府部门应通过动态调整补偿标准、建立多元主体补偿方式、推动林地产权市场化运作等方式提高政策的执行成效。

杉木土壤酚酸物质对草珊瑚生长和品质的影响

【目的】探究杉木人工林土壤中含量较高的4种酚酸物质对草珊瑚生长和品质的化感效应,为杉木林下套种草珊瑚提供理论依据,同时为利用其化感效应指导生产提供参考。【方法】以3个月生草珊瑚为试验材料,分别施加20,40,60,80 mg/L的对羟基苯甲酸、阿魏酸、香草酸和没食子酸处理液,以清水处理为对照,探究其对草珊瑚幼苗生长(苗高增量、地径增量、地上生物量、地下生物量)、光合生理(光合色素含量、净光合速率、蒸腾速率、气孔导度、胞间CO_(2)浓度)和药用成分(异嗪皮啶、绿原酸、迷迭香酸、总黄酮)含量的影响,利用平均敏感指数、相关性分析和主成分分析进行综合评价。【结果】①与对照相比,20~60 mg/L对羟基苯甲酸、阿魏酸和没食子酸总体上对草珊瑚的苗高增量、地径增量、地上生物量、地下生物量以及异嗪皮啶、绿原酸、迷迭香酸和总黄酮单株含量表现出促进作用,而香草酸则仅在质量浓度为20~40 mg/L时表现出促进作用。②与对照相比,4种酚酸在质量浓度为20~40 mg/L时对草珊瑚叶片的净光合速率、气孔导度和蒸腾速率表现为促进作用;在20~60 mg/L时对叶绿素a、叶绿素b、总叶绿素及类胡萝卜素含量提升表现为促进作用;在质量浓度为80 mg/L时对胞间CO_(2)浓度表现为促进作用。③综合分析可知,酚酸处理下草珊瑚的光合生理指标与生长指标、药用成分之间有较强的相关性,说明在一定阈值内酚酸物质可通过增强草珊瑚植株的光合作用,进而促进草珊瑚生长及其体内药用成分的累积。【结论】4种杉木土壤酚酸物质对草珊瑚生长和品质整体呈现出低中质量浓度(20~60 mg/L)促进、高质量浓度(80 mg/L)抑制的化感效应,且20 mg/L阿魏酸、60 mg/L对羟基苯甲酸、40 mg/L的香草酸和没食子酸在促进草珊瑚生长和品质提升方面表现较优。

不同经营措施对马占相思人工林土壤呼吸的影响

以马占相思(Acacia mangium)人工林为研究对象,探讨间伐、皆伐、“皆伐+补种”、“间伐+补种”、封山育林等不同森林经营管理措施对马占相思人工林土壤呼吸的影响,明确影响土壤呼吸的关键环境因子。结果表明:采伐强度(间伐、皆伐、封山育林)、补种均对土壤呼吸速率产生显著影响,土壤呼吸速率从大到小依次为:间伐样地((3.36±0.05)μmol·m^(-2)·s^(-1))、皆伐样地((3.10±0.07)μmol·m^(-2)·s^(-1))、封山育林对照样地((2.83±0.07)μmol·m^(-2)·s^(-1));而补种后的样地土壤呼吸速率((2.73±0.06)μmol·m^(-2)·s^(-1))小于未补种样地((3.34±0.05)μmol·m^(-2)·s^(-1));不同经营管理措施的样地平均呼吸速率从大到小依次为:皆伐、“间伐+补种”、间伐、封山育林对照、“皆伐+补种”。间伐、皆伐后的林地土壤温度显著高于对照样地,而补种对土壤温度没有显著的影响。森林经营管理措施可以改变土壤呼吸速率对温度的敏感性系数(Q_(10)值)。森林经营管理措施对土壤营养元素产生显著影响,封山育林对照样地的土壤营养元素质量分数最高,“间伐+补种”样地最低。因此,在林业生产实践中,可采取合理的经营措施提升森林质量和调控森林碳循环过程。

基于结构方程模型的兴安落叶松天然林碳汇量驱动因素

【目的】探究兴安落叶松天然林碳汇量及其驱动机制,为提升该地区的碳汇功能提供理论依据。【方法】基于黑龙江省大兴安岭地区第7次和第8次国家森林资源连续清查获取的264块固定样地调查数据,考虑林木生长、枯损、进界和采伐4个碳库,分别从林分、气候、多样性、土壤、地形和采伐6个方面选取24项指标,通过逐步回归和结构方程模型,量化了各指标对兴安落叶松天然林碳汇量的影响。【结果】(1)2005—2010年间,该地区兴安落叶松天然林的平均碳汇量为(1.17±0.71)t/(hm^(2)·a)。(2)逐步回归模型的确定系数(R^(2))、均方根误差(RMSE)和平均绝对误差(MAE)分别为0.60、0.60 t/(hm^(2)·a)和0.45 t/(hm^(2)·a),表明所建模型精度较高。模型筛选出的变量包括Shannon-Wiener指数、郁闭度、土壤全氮、土壤全钾、优势木平均胸径、年平均降水量、坡度和林分平均年龄。(3)结构方程模型中各变量对林分碳汇量的路径系数依次为Shannon-Wiener指数(0.462)>郁闭度(0.357)>优势木平均胸径(0.313)>土壤全氮(0.286)>土壤全钾(−0.142)>年平均降水量(−0.107)>坡度(−0.069)。【结论】Shannon-Wiener指数、优势木平均胸径、郁闭度和土壤条件是影响碳汇量的重要驱动因子,可在后续经营中通过合理抚育间伐或冠下补植来调整林分的树种组成、郁闭度和土壤肥力,以达到提升兴安落叶松天然林碳汇功能的目的。

内蒙古大兴安岭林区白桦天然林单木胸径生长模型构建

【目的】为准确预测内蒙古大兴安岭林区的白桦天然林单木生长并制定适应性经营管理措施,构建包含气候因子和林木大小多样性因子的白桦单木胸径生长混合效应模型。【方法】数据来源于内蒙古大兴安岭林区第8和9次森林资源清查数据,共筛选出符合要求的固定样地97块,白桦样木4785株。基于筛选的数据,运用逐步回归法,构建传统单木胸径生长模型,并在此模型的基础上,引入样地随机效应,构建白桦单木胸径生长混合效应模型。利用十折交叉验证法分别对已构建的基础模型和混合效应模型进行检验。【结果】期初胸径的对数、大于对象木的断面积和、样地内胸径标准差、生长积温和年平均降雨量对白桦单木胸径生长量存在显著影响。与基础模型相比,混合效应模型的调整决定系数提高了0.1206,均方根误差降低了0.0971 cm2,模型的预测精度显著提高。十折交叉验证的结果表明混合效应模型同样表现出较好的拟合结果。【结论】包含气候因子和林木大小多样性因子的白桦单木胸径生长混合效应模型能精准预测白桦单木胸径的生长动态,可以为内蒙古大兴安岭林区的白桦天然林的科学经营提供支持。