Topographic and climatic controls on soil environments and net primary production in a rugged temperate hardwood forest in Korea

Eight years (1994–2001) of field data and a biogeochemical process model, BIOME-BGC, were used to examine effects of local topography and inter-annual climatic variability on soil physical (i.e., soil moisture and temperature) and biogeochemical (i.e., organic matter content, soil respiration, and leaf litter production) variables in a temperate hardwood forest in Korea. The field data were collected from adjacent south-facing (S) and north-facing (N) slopes, respectively, to examine effects of local topography, and were utilized to validate predictability according to BIOME-BGC which was applied to model unmeasured hydro-ecological processes [i.e., evapotranspiration, net primary production (NPP), and net ecosystem exchange of carbon]. Our field-data analyses indicated that soil-related variables including soil temperature, water content, organic matter, soil respiration, and floor leaf litter store significantly differed between the S and N slopes, while leaf litter production did not differ as significantly as the soil-related variables. The BIOME-BGC predictions showed good agreement with the mean field data aggregated across the slopes. Our simulation results and field observations indicated that the inter-annual variations of leaf litter production and maximum leaf area index were best explained by precipitation, both at a 1-year lag, while variation in annual NPP was well correlated with precipitation without a temporal lag. Our results imply that: (1) local topography needs to be explicitly considered in ecosystem studies as a forcing function generating spatial heterogeneity in soil physical and biogeochemical variables within a rugged landscape, and (2) water limits vegetation productivity in our study forest, in spite of a relatively high annual precipitation rate (1,579 mm year^–1).     

Assessing scale‐dependent effects on Forest biomass productivity based on machine learning

Estimating forest above‐ground biomass (AGB) productivity constitutes one of the most fundamental topics in forest ecological research. Based on a 30‐ha permanent field plot in Northeastern China, we modeled AGB productivity as output, and topography, species diversity, stand structure, and a stand density variable as input across a series of area scales using the Random Forest (RF) algorithm. As the grain size increased from 10 to 200 m, we found that the relative importance of explanatory variables that drove the variation of biomass productivity varied a lot, and the model accuracy was gradually improved. The minimum sampling area for biomass productivity modeling in this region was 140 × 140 m. Our study shows that the relationship of topography, species diversity, stand structure, and stand density variables with biomass productivity modeled using the RF algorithm changes when moving from scales typical of forest surveys (10 m) to larger scales (200 m) within a controlled methodology. These results should be of considerable interest to scientists concerned with forest assessment.     

鼎湖山森林生态系统演替过程中的能量生态特征

以时空替代的方法,将灌草丛、针叶林、针阔叶混交林和季风常绿阔叶林等４个处于同一空间下的群落当作同一样落演替进程中的４个阶段,研究了鼎湖山南亚热带森林演替过程中的能量生态特征。结果表明,鼎湖山南亚热带森林群落演替过程中,其垂直层次、叶面积指数、冠层对太阳辐射能的截获量、叶生物量、总生物量、总初级生产力、总呼吸量、净初级生产力、枯树木现存量和年输入量、昆虫啃食量、群落的能量现存量等随演替的进程而增加,     

Assessing bias in diameter at breast height estimated from tree rings and its effects on basal area increment and biomass

Above-ground forest productivity can be reliably estimated from tree-ring width measurements. In doing so, annual growth is linked to the tree’s basal area increment (BAI), which is the change in cross-sectional area associated with each annual ring. When BAI is estimated from ring-width series, a value for the diameter of the tree is required. This diameter is ideally measured in the field, but can also be estimated as the sum of the annual ring widths. Tree biomass can also be estimated directly from the diameter estimates derived from tree-rings. Summing the ring widths, however, typically underestimates the tree’s true diameter. To evaluate this potential bias in diameter, we compared field-measured diameter and diameter estimated from the sum of the ring widths using tree-ring chronologies for seven common species in the eastern United States. We then evaluated the impacts of using the biased diameter estimates on derived BAI and biomass values. To simulate field-sampling error (i.e., failure to reach the pith when obtaining a core sample), we re-calculated BAI and biomass after removing a portion of the innermost rings from each tree. Comparisons of these various methods quantify the substantial and consistent underestimations in forest productivity estimates. To reduce the bias in diameter when using ring widths, we developed a regression model to adjust the diameter using core samples. This model is predicated on having some field-measured diameter values available at a site to calibrate and validate the model, but it can then be used to produce estimates at similar sites with similar species where no field-measured diameter values are available. Values of BAI and biomass derived from model-estimated diameter were more accurate at representing absolute growth than values produced by using the sum of the ring widths. Assessing the interannual variations in tree-growth is dependent on having metrics that accurately reflect the area and mass of wood produced. Our results suggest that published estimates of BAI and biomass using the sum of the ring widths to estimate diameter have substantially underestimated these productivity metrics. Our new procedure allows for more reliable estimates of productivity metrics that use diameter-at-breast height derived from tree rings.     

Solar radiation and functional traits explain the decline of forest primary productivity along a tropical elevation gradient

One of the major challenges in ecology is to understand how ecosystems respond to changes in environmental conditions, and how taxonomic and functional diversity mediate these changes. In this study, we use a trait‐spectra and individual‐based model, to analyse variation in forest primary productivity along a 3.3 km elevation gradient in the Amazon‐Andes. The model accurately predicted the magnitude and trends in forest productivity with elevation, with solar radiation and plant functional traits (leaf dry mass per area, leaf nitrogen and phosphorus concentration, and wood density) collectively accounting for productivity variation. Remarkably, explicit representation of temperature variation with elevation was not required to achieve accurate predictions of forest productivity, as trait variation driven by species turnover appears to capture the effect of temperature. Our semi‐mechanistic model suggests that spatial variation in traits can potentially be used to estimate spatial variation in productivity at the landscape scale.     

Effects of biodiversity,stand factors and functional identity on biomass and productivity during the restoration of subtropical forests in Central China

恢复梯度上华中亚热带森林生物多样性、林分因子及功能特性对生物量、生产力的影响 草地群落上进行的控制实验大都发现生物多样性对生态系统功能有显著促进作用。然而,在天然林中,多样性与林分因子、群落功能特性的相对作用大小仍存在争议。本文在森林恢复梯度上,研究这3类因素对生物量和生产力的相对影响。我们在湖北神农架设置了处于不同恢复阶段的24块(600 m²)亚热 带森林样地,计算了林分生物量和生产力。选择5个关键的植物功能性状,并计算了群落的功能多样性(功能丰富度、功能均匀度和功能离散度)和性状的加权平均值(CWM)。使用一般线性模型(GLMs)、变异分离等方法探究林分因子(密度、林龄、群落最大树高等)、功能特性、物种和功能多样性对生物量和生产力的相对重要性。研究结果表明,随着森林恢复,林分生物量和生产力显著增加,群落物种丰富度显著增加,而功能离散度显著降低。变异分离结果表明,多样性对生物量和生产力的单独效应不显著,但可能通过与林分因子和功能特性的协同效应来影响生物量和生产力。总体而言,我们发现林分因子对亚热带森林生物量和生产力的影响最大,功能特性显著影响生产力,但不影响生物量。这些结果说明,在森林经营中,调整林分结构和群落物种特性是提高森林碳储量和固碳潜力的有效途径。     

Annual soil respiration in broadleaf forests of northern Wisconsin: influence of moisture and site biological,chemical, and physical characteristics

Soil temperature and moisture influence soil respiration at a range of temporal and spatial scales. Although soil temperature and moisture may be seasonally correlated, intra and inter-annual variations in soil moisture do occur. There are few direct observations of the influence of local variation in species composition or other stand/site characteristics on seasonal and annual variations in soil moisture, and on cumulative annual soil carbon release. Soil climate and soil respiration from twelve sites in five different forest types were monitored over a 2-year period (1998–1999). Also measured were stand age, species composition, basal area, litter inputs, total above-ground wood production, leaf area index, forest floor mass, coarse and fine root mass, forest floor carbon and nitrogen concentration, root carbon and nitrogen concentration, soil carbon and nitrogen concentration, coarse fraction mass and volume, and soil texture. General soil respiration models were developed using soil temperature, daily soil moisture, and various site/soil characteristics. Of the site/soil characteristics, above-ground production, soil texture, roots + forest floor mass, roots + forest floor carbon:nitrogen, and soil carbon:nitrogen were significant predictors of soil respiration when used alone in respiration models; all of these site variables were weakly to moderately correlated with mean site soil moisture. Daily soil climate data were used to estimate the annual release of carbon (C) from soil respiration for the period 1998–1999. Mean annual soil temperature did not differ between the 2 years but mean annual soil moisture was approximately 9% lower in 1998 due to a summer drought. Soil C respired during 1998 ranged from 8.57 to 11.43 Mg C ha⁻¹ yr⁻¹ while the same sites released 10.13 and 13.57 Mg C ha⁻¹ yr⁻¹ in 1999; inter-annual differences of 15.41 and 15.73%, respectively. Among the 12 sites studied, we calculated that the depression of soil respiration linked to the drought caused annual differences of soil respiration from 11.00 to 15.78%. Annual estimates of respired soil C decreased with increasing site mean soil moisture. Similarly, the difference of respired carbon between the drought and the non-drought years generally decreased with increasing site mean soil moisture.     

Higher treefall rates on slopes and waterlogged soils result in lower stand biomass and productivity in a tropical rain forest

1.  Relationships between tropical rain forest biomass and environmental factors have been determined at regional scales, e.g. the Amazon Basin, but the reasons for the high variability in forest biomass at local scales are poorly understood. Interactions between topography, soil properties, tree growth and mortality rates, and treefalls are a likely reason for this variability.
2.  We used repeated measurements of permanent plots in lowland rain forest in French Guiana to evaluate these relationships. The plots sampled topographic gradients from hilltops to slopes to bottomlands, with accompanying variation in soil waterlogging along these gradients. Biomass was calculated for >175 tree species in the plots, along with biomass productivity and recruitment rates. Mortality was determined as standing dead and treefalls.
3.  Treefall rates were twice as high in bottomlands as on hilltops, and tree recruitment rates, radial growth rates and the abundance of light-demanding tree species were also higher.
4.  In the bottomlands, the mean wood density was 10% lower than on hilltops, the basal area 29% lower and the height:diameter ratio of trees was lower, collectively resulting in a total woody biomass that was 43% lower in bottomlands than on hilltops.
5.  Biomass productivity was 9% lower in bottomlands than on hilltops, even though soil Olsen P concentrations were higher in bottomlands.
6.   Synthesis . Along a topographic gradient from hilltops to bottomlands there were higher rates of treefall, which decreased the stand basal area and favoured lower allocation to height growth and recruitment of light-demanding species with low wood density. The resultant large variation in tree biomass along the gradient shows the importance of determining site characteristics and including these characteristics when scaling up biomass estimates from stand to local or regional scales.     

Biomass Stock and Productivity of Primeval and Production Beech Forests: Greater Canopy Structural Diversity Promotes Productivity

Our knowledge of temperate broadleaf forest ecology is based mostly on the study of production forests, which lack the terminal stage of forest development and have a simpler stand structure than old-growth and primeval forests. How primeval and production forests differ in net primary production (NPP) is not well known. In three primeval and three nearby production forests of European beech (Fagus sylvatica) in the Slovakian Carpathians, we measured aboveground biomass stocks (live and dead), aboveground NPP (ANPP) and parameters characterizing canopy structural diversity (leaf area index and its spatial variation). Our study aims were (1) to explore the role of canopy structural diversity for ANPP and (2) to assess evidence of a productivity decline in the terminal stage. While aboveground live biomass stocks were on average 20% greater in the primeval forests (386 vs. 320 Mg ha^?1; insignificant difference at two sites), deadwood mass stocks were on average four times larger than in the production forests (86 vs. 19 Mg ha^?1). ANPP was similarly high in the primeval and production forests (10.0 vs. 9.9 Mg ha^?1 y^?1) and did not decrease towards the terminal stage. Production models indicate that, in the primeval forests, about 10% of ANPP (ca. 1 Mg ha^?1 y^?1) was generated by effects related to leaf area heterogeneity, evidencing a positive effect of structural diversity on forest productivity, even though species diversity was low. This study helps to better understand the impact of forest management on the productivity and carbon storage in temperate woodlands.     

The global relationship between forest productivity and biomass

Aim  We aim to determine the empirical relationship between above-ground forest productivity and biomass. There are theoretical reasons to assume a relationship between forest structure and function, as both may be influenced by similar ecological factors such as moisture supply. Also, dynamic global vegetation model simulations imply that any increase in forest productivity driven by climate change will result in increases in biomass and therefore carbon storage. However, few studies have explored the strength and form of the relationship between forest productivity and biomass, whether in space or time.
Location Global scale.
Methods  We collated a large data set of above-ground biomass (AGB) and above-ground net primary productivity (ANPP) and tested the extent to which spatial variation in forest biomass across the Earth can be predicted from forest productivity.
Results  The global ANPP–AGB relationship differs fundamentally from the strongly positive, linear relationship reported in earlier analyses, which mostly lacked tropical sites. AGB begins to peak at c . 15–20 Mg ha⁻¹ year⁻¹ ANPP, plateaus at ANPP > 20–25 Mg ha⁻¹ year⁻¹, and may actually decline at higher levels of production.
Main conclusions  High turnover rates in high-productivity forests may limit AGB by promoting the dominance of species with a low wood density. Predicted increases in ANPP will not necessarily favour increases in forest carbon storage, especially if changes in productivity are accompanied by compositional shifts.     

中国南方3种主要人工林生物量和生产力的动态变化

基于中国南方杉木、马尾松、桉树3种主要人工林的幼龄林、中龄林、近熟林、成熟林、过熟林5个不同年龄各3块1000 m2样地(共计45块)的建立和调查,采用样木回归分析法(乔木层)和样方收获法(灌木层、草本层、地上凋落物)获取不同林型不同林龄径级样木和其它基本数据,探讨了3种人工林各组分各层次林分生物量和生产力的分配特征及随林龄的变化规律,结果表明,林分生物量和生产力与林龄密切相关,增长模型的拟合度均较高,相关显著;杉木、马尾松、桉树人工林的生物量随林龄的增长呈增加趋势,成熟林的生物量分别为192.30、191.53、105.77 Mg/hm2,其中活体植物分别占95.76%—98.39%、75.01%—99.14%、85.60%—97.61%;生物量的层次分配乔木层占绝对优势,并随年龄而增加,其它层次所占比例较小,总体趋势为凋落物草本层灌木层;乔木层的器官分配以干所占比例最高,杉木、马尾松、桉树分别占54.89%—75.97%、49.93%—83.10%、51.07%—98.48%,随年龄的增加而增加,根的比例次之,枝叶所占比例较小,随林龄而下降;灌木层器官分配以枝的相对生物量较大,草本层的地上和地下分配规律不明显;与其它森林类型相比,杉木和马尾松的生物量处于中上游水平,桉树的生物量较低,但3种人工林的生产力均很高,分别为12.37、8.98、21.10 Mg hm-2a-1,均是光合效率高、固碳潜力大的中国南方速生丰产优良造林树种。     

基于MODIS的泾河流域植被动态年际变化

以中分辨率成像光谱仪数据(Moderate resolution imaging spectroradiometer, MODIS)为基础计算泾河流域归一化差异植被指数(Normalized difference vegetation index, NDVI)在2001~2004年的时间序列值,分别采用相关系数r值和成对t检验的t值定量描述年内NDVI曲线在年际间的协同性和差异性。以农田、森林、灌丛和草地4种土地利用类型NDVI曲线在年际间变化显著的面积百分比为参数,在2001~2004年间分为1、2和3年间隔共6个时间组,比较分析4种土地利用类型的NDVI曲线在6个时间组内的协同性和差异性,进而探讨泾河流域植被年际变化及其与土地利用之间的关系。结果表明:4种土地利用类型NDVI波动对外界环境的响应在不同的时间间隔里表现一致,在2001~2003年和2001~2004年间变化比较明显;在各个时间组内比较发现有较大面积的农田和草地NDVI协同性较差,尤其在2001~2002年间,这可能与退耕还林还草政策的实施有关;4年来泾河流域内4种土地利用类型的NDVI值有增加趋势,植被状况趋于良好;NDVI年际间差异最明显的是草地,其次是农田和灌丛,森林的NDVI比较稳定。     

阿尔泰山落叶松林碳储量与生产力时空特征及其气候成因分析

准确把握阿尔泰山落叶松林固碳的动态变化对于维护阿尔泰山地森林生态系统的稳定性具有重要作用。基于4期(2001、2006、2011、2016年)森林资源连续清查资料,采用一元生物量模型、生物量与生产力关系方程、标准系数法和因子分析法等方法,估算了阿尔泰山落叶松林碳密度、碳储量和生产力(NPP),分析其时空变化特征,并探讨了阿尔泰山落叶松林固碳的气候成因。结果表明:(1)2001—2016年间阿尔泰山落叶松林固碳整体呈增长趋势,但增长幅度不大。(2)阿尔泰山落叶松林碳储量呈"富蕴阿勒泰哈巴河、青河布尔津福海"的分布特征;碳密度及NPP表现出"东南高,西北低"的空间分布格局;垂直分布上,碳储量、碳密度及NPP均呈随海拔升高先增后降的变化特征,在北坡和西北坡最大。(3)阿尔泰山落叶松林碳密度及NPP均随气温的升高而增加,是其主导影响因素。     

Can spatial variation and inter-annual variation in precipitation explain the seed density and species richness of the germinable soil seed bank in a tropical dry forest in north-eastern Brazil?

The interaction between microhabitat and inter-annual variation in precipitation has an important role on the dynamics of the seed bank and can play a crucial role in survival and maintenance of plant populations in semi-arid environments. We hypothesized that the type of microhabitat and the inter-annual variability in precipitation can explain the richness and density of the seed bank in a semi-arid region in Brazil. The study was conducted in an area of tropical dry forest with shrub-tree physiognomy, locally called caatinga. We collected 35 soil samples in three distinct microhabitats, at the end of rainy and dry seasons, respectively, over three years, totalling 630 samples. The seed bank (richness and seed density) were determined by seedling emergence method. Over the three years, 79 species emerged from the seed bank, 64, 45 and 42 in riparian, non-riparian and rocky microhabitats, respectively. We recorded differences in species richness and average density between microhabitats and between years, with significant statistical interaction between them. Inter-annual precipitation explained 48% and 5% of the variation in richness and seed density, respectively. Spatial variation explained 7% of the species richness and 31% of the density. Our results show that the interaction between spatial variation and precipitation has an important role on the spatial and temporal heterogeneity of the richness and density of seed banks in dry environments.     

Environmental factors influencing herb layer productivity in Central European oak forests: insights from soil and biomass analyses and a phytometer experiment

Habitat productivity and vegetation biomass are important factors affecting species diversity and ecosystem function, but factors determining productivity are still insufficiently known, especially in the forest herb layer. These factors are difficult to identify because different methods often yield different results. We sampled the herb layer biomass and assessed soil nutrients, moisture and light availability in 100 m² plots in Czech oak forests. Habitat productivity was estimated independently from nutrient content in the soil, herb layer biomass and using a bioassay experiment (growing phytometer plants of Raphanus sativus under standardised conditions in soil samples taken from forest plots). The generalised linear model for herb layer biomass showed it to increase with light, soil phosphorus and moisture availability, but only 10.7% of its variation was explained by these factors. The phytometer biomass increased mainly with soil pH and phosphorus availability; together with soil C/N ratio these factors explained 56.1% of the phytometer biomass variability. Combined evidence based on different approaches indicates that canopy shading and soil phosphorus tend to be the most important factors influencing the herb layer productivity of the studied oak forests.     

Structure and dynamics of the mangrove forest in the Rancheria River delta, Colombian Caribbean

We registered seedling survival and biomass increase for Rhizophora mangle L., Avicennia germinans L. and Laguncularia racemosa (L.) Gaertn. f, main mangrove species in the Rancheria River delta, Colombia. Only seedlings of R. mangle were found to survive. We also measured maximum rate of litterfall. We estimated annual litterfall through interpolation within an exponential regression performed with maximum and annual litterfall data published in other sources; the value of annual litterfall for the area was estimated to be 12.9 mgha(-1)y(-1). We found a 7.4 mgha(-1)y(-1)(-1) increase in biomass. Litterfall constitutes the larger fraction of the 20.2 mgha(-1)y(-1) productivity of this mangrove. We believe this is a very high value for a forest under unfavorable natural and human conditions, such as high seasonality and continuous use of the forest to feed goats and sheep. We consider that the high productivity is a response to both natural and anthropogenic stress.     

黑河流域植被水分利用效率时空分异及其对降水和气温的响应

植被水分利用效率(WUE)是衡量植被生态系统碳水耦合关系的重要指标,研究其时空分异特征对区域水资源合理利用及配置有重要意义。基于改进的光能利用率模型CASA,模拟估算了黑河流域2000—2013年植被净初级生产力(NPP),结合ETWatch模型估算的黑河流域2000—2013年蒸散数据ET,进一步估算了黑河流域植被水分利用效率WUE。分析了黑河流域NPP、ET和WUE空间格局和时间变化特征,探讨了WUE变化对降水和气温的相关性。结果表明:1)黑河流域空间上植被NPP在2000—2013年多年平均值为81.05 gC m^-2 a^-1,ET平均值为133.38 mm,植被WUE平均值为0.448 gC mm^-1 m^-2。植被NPP、ET与WUE的空间格局基本上类似,均呈现出自上游至下游逐渐减少的分布格局。2)黑河流域2000—2013年间植被平均NPP与平均WUE均呈现显著上升趋势(P<0.05),而ET平均值变化不显著。WUE年际变化斜率与其平均值在空间分布上存在一定的对应关系,空间上植被WU...     

Leaf traits and associated ecosystem characteristics across subtropical and timberline forests in the Gongga Mountains,Eastern Tibetan Plateau

Knowledge of how leaf characteristics might be used to deduce information on ecosystem functioning and how this scaling task could be done is limited. In this study, we present field data for leaf lifespan, specific leaf area (SLA) and mass and area-based leaf nitrogen concentrations (N_mass, N_area) of dominant tree species and the associated stand foliage N-pool, leaf area index (LAI), root biomass, aboveground biomass, net primary productivity (NPP) and soil available-N content in six undisturbed forest plots along subtropical to timberline gradients on the eastern slope of the Gongga Mountains. We developed a methodology to calculate the whole-canopy mean leaf traits to include all tree species (groups) in each of the six plots through a series of weighted averages scaled up from leaf-level measurements. These defined whole-canopy mean leaf traits were equivalent to the traits of a leaf in regard to their interrelationships and altitudinal trends, but were more useful for large-scale pattern analysis of ecosystem structure and function. The whole-canopy mean leaf lifespan and leaf N_mass mainly showed significant relationships with stand foliage N-pool, NPP, LAI and root biomass. In general, as elevation increased, the whole-canopy mean leaf lifespan and leaf N_area and stand LAI and foliage N-pool increased to their maximum, whereas the whole-canopy mean SLA and leaf N_mass and stand NPP and root biomass decreased from their maximum. The whole-canopy mean leaf lifespan and stand foliage N-pool both converged towards threshold-like logistic relationships with annual mean temperature and soil available-N variables. Our results are further supported by additional literature data in the Americas and eastern China.     

Precipitation Pattern Determines the Inter-annual Variation of Herbaceous Layer and Carbon Fluxes in a Phreatophyte-Dominated Desert Ecosystem

Arid and semi-arid ecosystems dominated by shrubby species are an important component in the global carbon cycle but are largely under-represented in studies of the effect of climate change on carbon flux. This study synthesizes data from long-term eddy covariance measurements and experiments to assess how changes in ecosystem composition, driven by precipitation patterns, affect inter-annual variability of carbon flux and their components in a halophyte desert community dominated by deep-rooted shrubs (phreatophytes, which depend on groundwater as their primary water source). Our results demonstrated that the carbon balance of this community responded strongly to precipitation variations. Both pre-growing season precipitation and growing season precipitation frequency significantly affected inter-annual variations in ecosystem carbon flux. Heavy pre-growing season precipitation (November–April, mostly as snow) increased annual net ecosystem carbon exchange, by facilitating the growth and carbon assimilation of shallow-rooted annual plants, which used spring and summer precipitation to increase community productivity. Sufficient pre-growing season precipitation led to more germination and growth of shallow-rooted annual plants. When followed by high-frequency growing season precipitation, community productivity of this desert ecosystem was lifted to the level of grassland or forest ecosystems. The long-term observations and experimental results confirmed that precipitation patterns and the herbaceous component were dominant drivers of the carbon dynamics in this phreatophyte-dominated desert ecosystem. This study illustrates the importance of inter-annual variations in climate and ecosystem composition for the carbon flux in arid and semi-arid ecosystems. It also highlights the important effect of changing frequency and seasonal pattern of precipitation on the regional and global carbon cycle in the coming decades.     

How is light interception efficiency related to shoot structure in tall canopy species?

Coexistence of multiple species is a fundamental aspect of plant and forest ecology. Although spatial arrangement of leaves within crowns is an important determinant of light interception and productivity, shoot structure varies considerably among coexisting canopy species. We investigated the relative importance of structural traits in determining the light availability of leaves (I) and light interception efficiency at the current-year shoot level (LIE_CS; the total light interception of leaves divided by shoot biomass) at the top of crowns of 11 canopy species in a cool-temperate forest in Japan. In accordance with Corner’s rules, the total mass, stem mass, total mass of leaf laminae, individual leaf area, and stem cross-sectional area of current-year shoot were positively correlated with each other, and branching intensity (the number of current-year shoots per branch unit of 1-m length) was inversely correlated with these traits across species. In contrast, I was correlated not with these traits, but with leaf elevation angle (a _L). Moreover, variation in LIE_CS across species was caused by variation in I (thus in a _L). Thus, a _L is a key parameter for the leaf light interception of canopy shoots in this cool-temperate forest. Differences in a _L across species might be related to different physiological strategies that developed in the high light and water-limited environment of forest canopies. Small variation in the length of current-year shoots among species implies that variations in I and LIE_CS would be important for the coexistence of these canopy species.