What diameter?What height?Influence of measures of average tree size on area-based allometric volume relationships

Volume is an important attribute used in many forest management decisions.Data from 83 fixed-area plots located in central New Brunswick,Canada,are used to examine how different measures of stand-level diameter and height influence volume prediction using a stand-level variant of Honer's(1967)volume equation.When density was included in the models(Volume=f(Diameter,Height,Density))choice of diameter measure was more important than choice of height measure.When density was not included(Volume=f(Diameter,Height)),the opposite was true.For models with density included,moment-based estimators of stand diameter and height performed better than all other measures.For models without density,largest tree estimators of stand diameter and height performed better than other measures.The overall best equation used quadratic mean diameter,Lorey's height,and density(root mean square error=5.26 m^3·ha^(-1);1.9%relative error).The best equation without density used mean diameter of the largest trees needed to calculate a stand density index of 400 and the mean height of the tallest 400 trees per ha(root mean square error=32.08 m^(3)·ha^(-1);11.8%relative error).The results of this study have some important implications for height subsampling and LiDAR-derived forest inventory analyses.

Ecological Networks of Allometric Growth,Feeding Behavior and Gut Microbiota in Chinese Alligator Hatchlings

Chinese alligator hatchlings in captivity are fragile and have a high mortality rate within first year.The body mass gain of reptile animals is closely related to their feeding behavior and gut microbiota.This study analyzed the intrinsic factors influencing the allometric growth of Chinese alligator hatchlings based on their body mass gain,feeding behavior,and gut microbiota.This information would enhance the health management of Chinese alligator hatchlings.There was a significant correlation between the total distance moved,the average number of conspecifics nearby,and body mass gain.Chinese alligator hatchlings with a greater growth rate showed greater activity and more independent behavior during feeding than those with a lower growth rate.Moreover,after feeding started,some functions of the gut microbiota showed significant relationships with growth rate and feeding activity.Chinese alligator hatchlings with a greater growth rate showed greater levels of heme biosynthesis than those with a lower growth rate,and feeding activity was inhibited by long-chain fatty acid biosynthesis.These results elucidate the relationships between health,feeding behavior,and the gut microbiota of Chinese alligator hatchlings.Understanding the intrinsic factors of their health and feeding behavior can improve the health management of Chinese alligator hatchlings in captivity for conservation.

Geographic Differences in Allometric Patterns of Males of the Japanese Firefly Luciola parvula

It has been well known for many years that males of Luciola parvula (Coleoptera, Lampyridae) have two morphs, namely small and large morphs in Japan. This article performed a statistical reanalysis of their morphological measurements based on previously published data and compared them. As a result, the two morphs were found to have different allometric patterns in the Hakone and Nagano areas, Japan. In Hakone, the relationships between their pronotum width and length were expressed by a common allometric line and a shift in location along the line. However, in Nagano, the relationships between their pronotum width and body length were expressed by two parallel allometric lines (a common slope and different intercepts). The allometric pattern of males of this species may vary among different parts of the body or among different areas. Therefore, this article recommends future studies to measure the same parts of the body as previous studies to clarify geographic variation in allometric relationships.

Are allometric model parameters of aboveground biomass for trees phylogenetically constrained?

Knowledge of which biological and functional traits have,or lack,phylogenetic signal in a particular group of organisms is important to understanding the formation and functioning of biological communities.Allometric biomass models reflecting tree growth characteristics are commonly used to predict forest biomass.However,few studies have examined whether model parameters are constrained by phylogeny.Here,we use a comprehensive database(including 276 tree species) compiled from 894 allometric biomass models published in 302 articles to examine whether parameters a and b of the model W=aD~b(where W stands for aboveground biomass,D is diameter at breast height) exhibit phylogenetic signal for all tree species as a whole and for different groups of tree species.For either model parameter,we relate difference in model parameter between different tree species to phylogenetic distance and to environmental distance between pairwise sites.Our study shows that neither model parameter exhibits phylogenetic signals(Pagel's λ and Blomberg's K both approach zero).This is the case regardless of whether all tree species in our data set were analyzed as a whole or tree species in different taxonomic groups(gymnosperm and angiosperm),leaf duration groups(evergreen and deciduous),or ecological groups(tropical,temperate and boreal) were analyzed separately.Our study also shows that difference in each parameter of the allometric biomass model is not significantly related to phylogenetic and environmental distances between tree species in different sites.

Filling the“vertical gap”between canopy tree species and understory shrub species:biomass allometric equations for subcanopy tree species

Subcanopy tree species are an important component of temperate secondary forests.However,their biomass equations are rarely reported,which forms a“vertical gap”between canopy tree species and understory shrub species.In this study,we destructively sampled six common subcanopy species(Syringa reticulate var.amurensis(Rupr.)Pringle,Padus racemosa(Lam.)Gilib.,Acer ginnala Maxim.,Malus baccata(Linn.)Borkh.,Rhamnus davurica Pall.,and Maackia amurensis Rupr.et Maxim.)to establish biomass equations in a temperate forest of Northeast China.The mixed-species and species-specifi c biomass allometric equations were well fi tted against diameter at breast height(DBH).Adding tree height(H)as the second predictor increased the R^(2)of the models compared with the DBH-only models by–1%to+3%.The R^(2)of DBH-only and DBH-H equations for the total biomass of mixed-species were 0.985 and 0.986,respectively.On average,the biomass allocation proportions for the six species were in the order of stem(45.5%)>branch(30.1%)>belowground(19.5%)>foliage(4.9%),with a mean root:shoot ratio of 0.24.Biomass allocation to each specifi c component diff ered among species,which aff ected the performance of the mixed-species model for particular biomass component.When estimating the biomass of subcanopy species using the equations for canopy species(e.g.,Betula platyphylla Suk.,Ulmus davidiana var.japonica(Rehd.)Nakai,and Acer mono Maxim.),the errors in individual biomass estimation increased with tree size(up to 68.8%at 30 cm DBH),and the errors in stand biomass estimation(up to 19.2%)increased with increasing percentage of basal area shared by subcanopy species.The errors caused by selecting such inappropriate models could be removed by multiplying adjustment factors,which were usually power functions of DBH for biomass components.These results provide methodological support for accurate biomass estimation in temperate China and useful guidelines for biomass estimation for subcanopy species in other regions,which can help to improve estimates of forest biomass and carbon stocks.

The worldwide allometric relationship in anatomical structures for plant roots

The cortex(i.e.,absorptive tissue)and stele(transportive vascular tissue)are fundamental to the function of plant roots.Unraveling how these anatomical structures are assembled in absorptive roots is essential for our understanding of plant ecology,physiology,and plant responses to global environmental changes.In this review,we first compile a large data set on anatomical traits in absorptive roots,including cortex thickness and stele radius,across 698 observations and 512 species.Using this data set,we reveal a common root allometry in absorptive root structures,i.e.,cortex thickness increases much faster than stele radius with increasing root diameter(hereafter,root allometry).Root allometry is further validated within and across plant growth forms(woody,grass,and liana species),mycorrhiza types(arbuscular mycorrhiza,ectomycorrhiza,and orchid mycorrhizas),phylogenetic gradients(from ferns to Orchidaceae),and environmental change scenarios(e.g.,elevation of atmospheric CO_(2)concentration and nitrogen fertilization).These findings indicate that root allometry is common in plants.Importantly,root allometry varies greatly across species.We then summarize recent research on the mechanisms of root allometry and potential issues regarding these mechanisms.We further discuss ecological and evolutionary implications of root allometry.Finally,we propose several important research directions that should be pursued regarding root allometry.

Developing allometric equations to estimate forest biomass for tree species categories based on phylogenetic relationships

The development of allometric biomass models is important process in biomass estimation because the reliability of forest biomass and carbon estimations largely depends on the accuracy and precision of such models.National Forest Inventories(NFI)are detailed assessments of forest resources at national and regional levels that provide valuable data for forest biomass estimation.However,the lack of biomass allometric equations for each tree species in the NFI currently hampers the estimation of national-scale forest biomass.The main objective of this study was to develop allometric biomass regression equations for each tree species in the NFI of China based on limited biomass observations.These equations optimally grouped NFI and biomass observation species according to their phylogenetic relationships.Significant phylogenetic signals demonstrated phylogenetic conservation of the crown-to-stem biomass ratio.Based on phylogenetic relationships,we grouped and matched NFI and biomass observation species into 22 categories.Allometric biomass regression models were developed for each of these 22 species categories,and the models performed successfully(R^(2)=0.97,root mean square error(RMSE)=12.9​t·ha^(–1),relative RMSE=11.5%).Furthermore,we found that phylogeny-based models performed more effectively than wood density-based models.The results suggest that grouping species based on their phylogenetic relationships is a reliable approach for the development and selection of accurate allometric equations.

Effects of Pruning Types on Tree Vigor of Bamboo-Leaf Oak Inferred from Allometric Analysis

There are two well-known types of tree pruning, crown raising and crown reduction. In Japan, the former has been rarely used, whereas the latter has been widely used. However, it remains unclear which type is more effective to maintain tree vigor and health. Bamboo-leaf oak (Quercus myrsinifolia) trees were experimentally planted and pruned with the two pruning types compared with the no-pruning type. In the crown raising, the lower part of each tree was pruned, and its dominant leader was maintained from the aspect of structural pruning, whereas in the crown reduction, the upper part of each tree was pruned, and the tree height was reduced. The oak trees were observed and recorded in terms of leaf area, leaf weight, branch weight, and tree shape for about one year. The morphological data were statistically analyzed in terms of their allometric relationships. The crown raising type shared the same allometric patterns with the no-pruning types, but the crown reduction type did not. The trees of the crown reduction type were more likely to suffer from pests and disease. The allometric differences between the two pruning types may be considered the result of a decline in whole-tree vigor and health in crown reduction. The crown raising seemed more likely to control tree vigor and health than the crown reduction. The present results would help arborists determine which method to use for pruning.

桂西南岩溶区植物叶性状的系统发育信号及其关联分析

【目的】探究岩溶植物叶性状在不同生活型水平上的差异以及系统发育保守性,有助于深入理解植物对异质性生境的适应机制,进而为岩溶植被的保护与恢复提供科学依据。【方法】以桂西南岩溶区20种常见阔叶木本植物为对象,采用K值法检验了叶性状的系统发育信号,并运用系统发育独立比较(PIC)和标准化主轴估计(SMA)的方法分析了叶性状间的关联适应性。【结果】1)研究区植物群落10个叶性状均未表现出较强的系统发育保守性,系统发育结构与性状结构并不完全一致。2)叶面积(LA)与叶长(LL)、叶宽(LW)以及叶组织密度(LTD)与LL、叶体积(LV)间均呈异速生长关系,而LL与LW、LA与叶干质量(LDW)间均呈等速生长关系;其中,LTD与LL的生长关系在常绿植物组发生了改变,由异速生长关系转变为等速生长关系;其他性状组合间的生长关系并未因生活型的不同而引起差异,表明常绿植物倾向于限制LL以适应环境的变化;3)LA、LL和LW以及LTD与LL、LV在常绿和落叶植物组间的斜率均沿共同主轴方向显著漂移(P<0.05),表明常绿和落叶植物对环境的适应策略发生了位移,常绿植物倾向于选择小叶、组织密度大的资源保守型生长策略,而落叶植物则倾向于选择大叶、组织密度小的资源获取型生长策略。【结论】生态位分化在很大程度上是促进亚热带阔叶林群落物种共存和生物多样性维持的重要机制。

气候对不同林型兴安落叶松林生产力的影响

以内蒙古大兴安岭地区两种林型的兴安落叶松(Larix gmelinii)天然林为对象,运用树木年轮学与异速生长方程模型,推算过去20 a杜香(Ledum palustre L.)-兴安落叶松林及草类-兴安落叶松林净初级生产力(N_(PP))的年际变化,结合中国气象数据网获取的气象数据,分析气候因子对不同林型兴安落叶松林N_(PP)的影响。结果表明:两种林型生物量呈逐年上升的趋势,N_(PP)呈“上升-下降-上升”的波动式上升趋势。不同林型N_(PP)与各气候因子的相关分析表明,2000—2020年温度(T)对两种林型兴安落叶松林N_(PP)起正向影响,而降水(P)对草类-兴安落叶松林N_(PP)起正向影响。由于气候的“滞后效应”,杜香-兴安落叶松林N_(PP)与上一年8月份月平均最高温度呈极显著正相关,草类-兴安落叶松林N_(PP)与上一年11月份月平均温度、上一年7月份降水量呈显著正相关。

黄河流域生态承载力及人地关系可持续发展——基于异速生长模型的研究

厘清黄河流域人口与土地异速生长关系的空间分异特征与时空变化趋势对协调黄河流域人地关系,提高黄河流域生态承载力有重要借鉴意义。文章引入生物学异速生长模型对黄河流域生态承载力的人地协调关系进行研究。结果表明:第一,黄河流域城市主要以正异速二级,土地明显扩张类型为主,其在黄河流域上中下游占比分别为44.45%、52.94%和84.61%。第二,以2015年为分界点,黄河流域异速生长系数有显著的阶段性转换特征。2015年前黄河流域异速生长系数总体呈现下降趋势,2015年后则小幅提升。从2013年开始,黄河上游异速生长类型由正异速转为负异速,黄河中下游一直为正异速生长。第三,黄河上中下游异速生长系数的全局莫兰指数均为负数,异速生长系数呈现高低集聚分布态势。第四,从影响土地和人口数量变化的因素上看,工业化水平、金融发展对土地扩张和人口增长均有正向促进作用,政府干预可促进人口增长,但教育资源不足成为抑制人口增长的重要因素。从而得到以下政策启示:在提高城市土地利用率的基础上,上中下游城市群均应充分利用市场机制对城市建设用地进行资源配置,进一步提高城市建设用地的利用效率,积极推进土地的二次开发和利用,优化城市土地的利用结构,积极发挥城市集聚效应,合理规划城市增长边界。

混交对杉木和山杜英混交林生长、结构和生产力的影响

为探究杉木(Cunninghamia lanceolata)与山杜英(Elaeocarpus sylvestris)的混交效应,以景德镇枫树山林场20年生杉木纯林、山杜英纯林和杉木-山杜英混交林为研究对象,每种林分类型设置3种坡位(上坡、中坡和下坡),分析树种混交对林分生长的影响,并分别探究混交效应对立地条件和生境因子的响应。结果表明:混交林蓄积较预期蓄积增加5%,表现略微增产;混交林中杉木蓄积较杉木纯林增加15%,混交林中山杜英蓄积较山杜英纯林减少13%。相对于纯林,两树种直径分布特征对混交的响应呈相反趋势,混交林中杉木直径分布峰值向高阶移动,而混交林中山杜英直径分布峰值向低阶移动。混交林及其纯林粗根直径-胸径的异速生长分析表明,混交林中杉木生长侧重于树干生长,而山杜英生长侧重于根系生长;无论林型和树种,坡位由上到下,林木生长会侧重于树干生长。杉木-山杜英混交效应与地位指数呈显著负相关(P<0.05),土壤有效磷是混交林生长的主要限制因子。杉木与山杜英混交可促进林分生长,且混交林对较差立地条件有更好的适应性。

不同林龄西南桦人工林的生物量及其分配特征

西南桦为我国南方主要造林树种,分布范围较广,开展不同林龄的西南桦人工林生物量及其分配特征研究,可为其科学经营及碳循环研究提供科学依据。为探讨西南桦人工林不同龄级林分生物量的组成、分配及变化趋势,本研究以采集于滇南和滇西南64块(666.7 m^(2))样地调查数据和150株西南桦样木生物量数据为研究对象,建立胸径(D)和树高(H)为变量的生物量异速生长方程。结果显示:(1)西南桦各器官生物量异速生长方程的预估精度均达98%以上,能较好地估测西南桦各器官生物量,西南桦人工林幼龄林、中龄林、近熟林、成过熟林森林平均总生物量分别为137.92、181.34、245.87、292.43 t·hm^(-2)。(2)从分配特征来看,乔木层生物量占绝对优势,其次为凋落物层、灌木层和草本层;从各器官来看,乔木层树干、灌木层的根、草本层的地上部分、凋落物层的枯落物生物量占各层生物量的比例最高。结果表明:西南桦人工林总生物量随林龄增大而增加,灌木层、草本层、凋落物层生物量随林龄增大无显著差异,西南桦人工林生物量较高,是一个固碳潜力大的造林树种。

云南松苗木N、P、K元素含量间异速生长关系对N、P添加的响应

为了解云南松苗木不同器官N、P、K的分布特征,分析云南松不同器官N、P、K含量间的分配差异,进一步探讨各器官N、P、K元素间的异速生长关系。采用N、P二因素三水平的方法开展不同施肥试验,并对苗木采样测定,研究云南松苗木N、P、K元素含量间异速生长关系对N、P添加的响应。结果表明,云南松苗木对N、P、K在不同器官间具有不同的分配策略,总体K变动较小,N、P波动较大且相似,在各器官中N、K分配表现为萌条>叶>茎>根;P表现为萌条>茎>叶>根。与对照相比,单施N、P和N、P配施均对云南松苗木生长的影响产生一定差异,总体来看N、P配施更能促进苗木的养分合理分配,有效缓解单施N、P对植株的限制作用,使养分处于一个平衡状态,进而促进苗木的生长。随施肥时间的推移,各器官营养元素间的异速生长关系也随之发生变化,且各器官表现为N、P的积累速度相接近,总体表现为K的积累速度低于N、P。总体而言,随施肥时间的改变,云南松苗木各器官之间元素的异速生长轨迹发生了显著变化,形成不同的营养元素分配模式。

长三角地区城区面积−绿地面积异速增长关系及协调性研究

城区面积与绿地面积发展关系是影响城市新型城镇化质量提高的关键问题。以长三角地区为研究区,利用异速增长模型和耦合协调度模型探讨2000―2020年城区面积与绿地面积的发展关系,分析城区面积−绿地面积异速增长与耦合协调的交互规律及影响因素。研究发现:①长三角城区面积和绿地面积呈现出“一极多核”的空间结构,其结构具有较强的稳定性。时间上,异速增长关系类型沿着绿地扩张弱型−城区绿地基本协调型−绿地扩张弱型演进;空间上,以绿地扩张弱型城市为主,即正异速增长型城市数量占据主导地位。②长三角城区面积与绿地面积的协调度总体呈上升趋势,协调度格局具有较强的稳定性,在空间上呈“东高西低”的分布格局,协调度空间差异呈扩大态势。③长三角城区面积与绿地面积协调度类型的数量结构由“金字塔型”转变为“橄榄型”,正异速增长型城市协调度趋于上升且空间差异较大,负异速增长型城市协调度趋于下降且空间差异较大。④城镇化率、人均GDP和人口密度对耦合协调度影响较强,第三产业比重、固定资产投资率、财政自给率耦合协调度和异速增长均有不同程度影响,各因素对耦合协调度的影响均超过异速增长。

蔡家川流域人工刺槐生物量模型的构建与比较

利用蔡家川流域不同立地条件下48株刺槐样木生物量的实测数据,以胸径、树高、冠幅、冠长及胸径、树高的复合因子为自变量,构建生物量异速生长模型、多元线性模型和相容性生物量模型。采用决定系数(R^(2))、均方根误差(RMSE)、估计标准误差(SEE)、总相对误差(TRE)、平均相对误差(ARE)和平均百分比误差(MPE)等6个指标对模型进行拟合度和精确度的检验。结果表明:以胸径(D_(BH))、树高(h)的复合因子构建的生物量模型估测效果较好。3种模型的检验指标均在可接受的范围内,均适用于蔡家川流域刺槐生物量的预测。其中,多元线性模型对树枝、树叶生物量预测效果最佳,预测精度为90.11%和89.72%;相容性生物量模型对总树干、根系和总生物量的预测精度高达91.38%、90.83%、93.90%,并且解决了各器官生物量与总生物量的相容性问题。构建的模型中,相容性生物量模型的估测效果最好,多元线性模型和生物量异速生长模型次之。

盐度对青虾幼虾生长及其异速生长的影响

为探讨盐度对青虾(Macrobrachium nipponense)幼虾生长及其异速生长的影响,本研究将1月龄青虾幼虾分别养殖在盐度0、7和14的水体中,每隔15 d分别随机抽样90尾并测定个体的体长、体质量等形态性状,计算并比较不同盐度中青虾幼虾生长速度。结果显示:在60 d的养殖过程中,青虾幼虾在盐度0中的平均体长、体质量均显著高于盐度7、14;第15、60天时,青虾幼虾在盐度0中的体长、体质量相对增长率均显著高于盐度7、14;不同盐度梯度下青虾幼虾个体生长速度均存在显著差异,体长、体质量的差异随养殖时间的增加而显著加大,其中盐度0中个体间异速生长差异程度最大,盐度14中个体间异速生长差异程度较小。综上所述,青虾幼虾在不同盐度中均存在异速生长现象,青虾幼虾在盐度14中个体间异速生长最小。

基于随机森林算法的桉树人工林单木生物量预估模型

单木生物量模型是估测森林生物量的基础。通过标准木法实测雷州半岛地区90株桉树单株生物量数据,随机划分60个样本数据作为训练集,30个样本数据作为验证集。以林龄、树高和胸径为自变量,单木生物量为因变量,使用岭回归模型、异速生长模型和随机森林算法构建模型,采用决定系数(R^(2))、均方根误差(RMSE)和平均绝对误差(MAE)对模型进行评价。结果表明:随机森林模型的R~2、RMSE和MAE无论在训练集还是验证集均高于岭回归模型和异速生长模型。由随机森林模型的因子重要值可知,胸径是影响单木生物量的主要因子。引入林龄因子后的随机森林模型可以提高单木生物量的预测精度,为碳汇计量提供基础数据和模型支撑。

浑善达克沙地黄柳小枝功能性状对风蚀环境响应的性别差异

植物功能性状及性状间权衡关系对揭示植物生长策略、资源分配模式以及探讨其生理生态过程的内在机制具有重要意义,但针对雌雄异株植物功能性状对其生境响应的性别差异却鲜有报道。以雌雄异株植物黄柳当年生末端小枝为研究对象,从枝水平、叶水平比较雌雄植株功能性状及性状间权衡关系对风蚀环境响应的性别差异。结果显示:小枝水平上,对照环境下雌雄植株茎干重-总叶干重之间的权衡均倾向于总叶干重,风蚀环境下则倾向于茎干重,且雌株权衡值分别为雄株的4.3倍和3.7倍;雌雄植株茎干重-总叶面积的权衡在各生境下均偏向于茎干重,两性的权衡值差异不大。叶水平上,相同叶片干重下,风蚀对雄株叶片面积生长的抑制作用更显著;雌株叶片干重与叶柄干重呈等速生长关系,而雄株呈小于理论值1的异速生长关系,且在风蚀环境中,相同叶柄干重下,雌株叶片干重的累积速率比雄株快。研究表明,黄柳雌雄植株小枝各功能性状间的关系对风蚀环境具有不同的响应,雌株比雄株更倾向于将资源投资在光合器官生长中,且风蚀对雄株光合器官生长的抑制作用更显著。

Tree allometry responses to competition and complementarity in mixed-species plantations of Betula alnoides

Tree allometry plays a crucial role in tree survival,stability,and timber quantity and quality of mixed-species plantations.However,the responses of tree allometry to resource utilisation within the framework of interspecific competition and complementarity remain poorly understood.Taking into consideration strong-and weakspace competition(SC and WC),as well as N_(2)-fixing and non-N_(2)-fixing tree species(FN and nFN),a mixedspecies planting trial was conducted for Betula alnoides,a pioneer tree species,which was separately mixed with Acacia melanoxylon(SC+FN),Erythrophleum fordii(WC+FN),Eucalyptus cloeziana(SC+nFN)and Pinus kesiya var.langbianensis(WC+nFN)in southern China.Six years after planting,tree growth,total nitrogen(N)and carbon(C)contents,and the natural abundances of^(15)N and^(13)C in the leaves were measured for each species,and the mycorrhizal colonisation rates of B.alnoides were investigated under each treatment.Allometric variations and their relationships with space competition and nutrient-related factors were analyzed.The results showed a consistent effect of space competition on the height-diameter relationship of B.alnoides in mixtures with FN or nFN.The tree height growth of B.alnoides was significantly promoted under high space competition,and growth in diameter at breast height(DBH),tree height and crown size were all expedited in mixtures with FN.The symbiotic relationship between ectomycorrhizal fungi and B.alnoides was significantly influenced by both space competition and N_(2) fixation by the accompanying tree species,whereas such significant effects were absent for arbuscular mycorrhizal fungi.Furthermore,high space competition significantly decreased the water use efficiency(WUE)of B.alnoides,and its N use efficiency(NUE)was much lower in the FN mixtures.Structural equation modeling further demonstrated that the stem allometry of B.alnoides was affected by its NUE and WUE via changes in its height growth,and crown allometry was influenced by the mycorrhizal symbiotic relationship.Our findings provide new insights into the mechanisms driving tree allometric responses to above-and belowground resource competition and complementarity in mixed-species plantations,which are instructive for the establishment of mixed-species plantations.