基于GreenLab原理构建油松成年树的结构-功能模型

 林木的结构-功能模型(functional-structural tree modeling, FSTMs)是基于器官级组件构建的将植物结构和功能结合起来的一类模型, 在应用于成年树时需要解决拓扑结构复杂性和年轮分配模式普适性的问题。该文以18年生和41年生的油松 (Pinus tabulaeformis)成年树为研究对象, 将GreenLab模型应用到成年树的模拟中。采用破坏性取样, 实测了2株油松成年树的形态结构, 利用子结构模型解决成年树拓扑结构复杂性的问题, 引入年轮影响系数λ, 将全局分配模式和Pressler模式结合起 来, 解决年轮分配模式在不同年龄和环境条件下不同的问题。模型的直接参数通过实测数据获得, 隐含参数利用非线性最小二乘法拟合反求获得。通过实测数据与模拟数据的对比、模拟数据与经验模型模拟数据的对比, 对模型的模拟效果进行了评估, 发现节间总重、针叶总重、树高、树干节间重观测值和模型模拟值建立的回归方程的决定系数为0.84–0.98, 结构-功能模型与经验模型对总生物量模拟的决定系数为0.95, 表明该模型能较真实地反映油松的结构和生长过程。     

基于源库生长单位的温室番茄干物质生产-分配模拟

为了量化研究温室番茄果穗间干物质的分配,提高温室番茄栽培的效益,采用源库生长单位的测定方法,将经典的单叶同化物生产模型与GreenLab模型相结合,构建了干物质向源库生长单位内茎节、叶片、果实分配的动态模型,利用越冬茬、早春茬和春夏茬温室番茄各器官的干物质测定数据对模型进行了验证.结果表明:所构建的模型模拟结果与实测结果吻合性较好,不同茬口同化物生产模拟值与实测值的回归方程斜率为0.93,R~2为0.92;源库生长单位内茎节、叶片、果实以及根系的模拟值与实测值间回归方程斜率在0.85～0.89之间,其相对误差(R_e)均值分别为5.3%、5.6%、8.1%和3.6%,说明模型的模拟准确度较高,可为不同茬口温室番茄栽培管理提供理论依据和决策支持.     

基于植株拓扑结构的生物量分配的玉米虚拟模型

依据植物结构—功能相互作用机理,建立了能模拟玉米生长发育与形态结构建成的虚拟模型。该模型的重要部分为基于植株拓扑结构的生物量分配模块。叙述了该模块的构建原理,以2000年田间试验数据提取了玉米的发育、生物量生产和生物量分配参数。模型模拟了2001年的玉米生长发育与生物量分配过程,模拟结果与田间试验结果比较吻合。应用该模型模拟了2001年玉米不同生育阶段植株的生物量分配和各器官生物量积累动态。     

基于无人机SfM数据的挺水植物生物量反演

生物量是衡量挺水植物生长状况的重要参数,对湿地生态系统健康评价具有重要意义。利用无人机影像生成运动重建结构Sf M(Structure from Motion,Sf M)数据,结合野外实测生物量构建定量反演模型,并根据反演模型对生物量进行空间制图,最后分析了挺水植物类型对生物量空间分布的影响。结果表明,文中基于Sf M数据建立的逐步线性回归模型(Stepwise Linear(SWL)regression model)具有较好的反演精度及估测能力。其模型显著性为显著(P0.01),决定系数为0.86,相对均方根误差为6.1%。挺水植物类型对生物量空间分布影响显著(P0.05)。通过对研究区挺水植物的生物量进行估算,为利用无人机遥感监测挺水植物生物量提供了新思路。     

绿洲生态系统生物量与植被指数分析

利用阜康绿洲野外实测的53个样方的植物生物量数据与同期陆地卫星MODIS影像的第1,2通道250 m遥感数据,分析植被指数与绿洲植物生物量的相关关系,建立植被指数与绿洲植物生物量的一元线性和非线性回归模型。结果表明,植被指数NDVI和MSAVI与绿洲生态系统植物生物量之间存在较好的相关性;所建植被指数与植物生物量的回归模型中,三次方程为所得到的回归模型中最适合用于绿洲生态系统植物生物量和生长监测。     

大兴安岭植被生物量的ALOS PALSAR估算

利用野外实测调查数据,系统分析了ALOS PALSAR L波段HH(L-HH)极化数据与大兴安岭地区森林各成分参数的关系,并采用简单线性模型、指数模型和加入地理因子模型建立森林生物量的估算模型进行最优反演.结果表明:后向散射系数与树木地上部分总生物量相关性最大,其次是干生物量,L-HH数据可以用来反演正确的树木地上部分总生物量.3种模型中,加入地理因子模型降低了植被生物量估算的误差,精度达0.851,反演结果与实际相符.在41.5°入射角L-HH极化数据下,大兴安岭塔河林业局和阿木尔林业局的森林生物量饱和点在15.4 kg·m-2.     

利用航空影像和雷达数据估算韩国单株个体赤松林的碳储量

利用航空影像和激光雷达数据, 对韩国赤松林的碳储量进行了估算. 基于雷达数据建立数字冠层模型, 再与航空影像融合, 进而划分单株树木的冠幅范围. 为消除分段误差, 采用高斯滤波方法对融合后的影像进行平滑, 然后利用标记控制阈值分割方法提取出单株树木的冠幅范围, 再通过建立实测冠幅面积和胸径间的回归方程计算出单株树木的胸径. 在此基础上, 利用韩国森林研究所建立的回归模型, 计算单株树木的地上生物量. 单株树木的碳储量由地上生物量乘以转化系数(0.5)得到. 结果显示, 用此方法估算的平均单株树木碳储量为193.7 kgC, 与实际测量值223.8 kgC较为接近, 说明本研究提供的基于航空影像和雷达的方法, 可以有效地估算大面积森林树木的生物量和碳储量.     

水曲柳落叶松人工混交林中树木个体生长的竞争效应模型

本研究从水曲柳落叶松混交林中树木的种内种间竞争机制出发,对与距离有关的竞争模型和邻体干扰模型进行了改进,提出了以竞争指数分量和竞争效应系数来量化树木间的空间竞争。根据野外的实测数据,以年材积生长量为因变量各竞争指数分量为自变量,通过多元回归分析建立了树木个体生长的竞争效应模型,回归结果有很好的拟合优度。本研究为空间竞争模型的进一步改进和生态学研究植物竞争生长关系提供了新的思路。     

树木叶片面积与叶柄长、节间长和叶倾角的关系初探

树木的叶片面积与叶柄长、节间长之间有着明显的内在联系．本文分析研究了这个联系,在适当的理想假设下通过数学建模得到了反映树木叶片面积与叶柄长、节间长和叶倾角之间的关系模型．接着,文章对模型的不合理之处进行了分析与改进,并得到叶片面积与节间长、心茎距之间的关系表达式．最后,本文利用分别采集到的13种互生和对生树木叶子上的相关数据对模型进行了检验．检验结果表明建立的模型是正确的,能够反映树木的叶片面积与叶柄长、节间长和叶倾角之间的相互数量关系．     

基于器官生物量构建植株形态的玉米虚拟模型

探讨了基于玉米器官生物量模拟其形态的方法,并应用2000年田间试验数据提取了玉米节间、叶鞘和叶片的形态构建参数。基于玉米虚拟模型生物量分配模块模拟的器官生物量积累和建立的形态构建方法与提取的参数,模拟了2001年玉米不同生长阶段的器官形态,模拟结果与田间试验数据吻合较好。应用本模型实现了玉米生长过程中植株各个器官形态变化以及植株高度、叶面积动态的模拟,并实现了植株形态的可视化。     

A Functional and Structural Mongolian Scots Pine (Pinus sylvestris var. mongolica) Model Integrating Architecture, Biomass and Effects of Precipitation

Mongolian Scots pine (Pinus sylvestris var. mongolica) is one of the principal tree species in the network of Three-North Shelterbelt for windbreak and sand stabilisation in China. The functions of shelterbelts are highly correlated with the architecture and eco-physiological processes of individual tree. Thus, model-assisted analysis of canopy architecture and function dynamic in Mongolian Scots pine is of value for better understanding its role and behaviour within shelterbelt ecosystems in these arid and semiarid regions. We present here a single-tree functional and structural model, derived from the GreenLab model, which is adapted for young Mongolian Scots pines by incorporation of plant biomass production, allocation, allometric rules and soil water dynamics. The model is calibrated and validated based on experimental measurements taken on Mongolian Scots pines in 2007 and 2006 under local meteorological conditions. Measurements include plant biomass, topology and geometry, as well as soil attributes and standard meteorological data. After calibration, the model allows reconstruction of three-dimensional (3D) canopy architecture and biomass dynamics for trees from one- to six-year-old at the same site using meteorological data for the six years from 2001 to 2006. Sensitivity analysis indicates that rainfall variation has more influence on biomass increment than on architecture, and the internode and needle compartments and the aboveground biomass respond linearly to increases in precipitation. Sensitivity analysis also shows that the balance between internode and needle growth varies only slightly within the range of precipitations considered here. The model is expected to be used to investigate the growth of Mongolian Scots pines in other regions with different soils and climates.     

Using L-systems for modeling source-sink interactions, architecture and physiology of growing trees: the L-PEACH model

Functional-structural plant models simulate the development of plant structure, taking into account plant physiology and environmental factors. The L-PEACH model is based on the development of peach trees. It demonstrates the usefulness of L-systems in constructing functional-structural models. L-PEACH uses L-systems both to simulate the development of tree structure and to solve differential equations for carbohydrate flow and allocation. New L-system-based algorithms are devised for simulating the behavior of dynamically changing structures made of hundreds of interacting, time-varying, nonlinear components. L-PEACH incorporates a carbon-allocation model driven by source-sink interactions between tree components. Storage and mobilization of carbohydrates during the annual life cycle of a tree are taken into account. Carbohydrate production in the leaves is simulated based on the availability of water and light. Apices, internodes, leaves and fruit grow according to the resulting local carbohydrate supply. L-PEACH outputs an animated three-dimensional visual representation of the growing tree and user-specified statistics that characterize selected stages of plant development. The model is applied to simulate a tree's response to fruit thinning and changes in water stress. L-PEACH may be used to assist in horticultural decision-making processes after being calibrated to specific trees.     

A virtual plant that responds to the environment like a real one: the case for chrysanthemum

? Plants respond to environmental change through alterations in organ size, number and biomass. However, different phenotypes are rarely integrated in a single model, and the prediction of plant responses to environmental conditions is challenging. The aim of this study was to simulate and predict plant phenotypic plasticity in development and growth using an organ-level functional-structural plant model, GreenLab. ? Chrysanthemum plants were grown in climate chambers in 16 different environmental regimes: four different temperatures (15, 18, 21 and 24°C) combined with four different light intensities (40%, 51%, 65% and 100%, where 100% is 340 μmol m?2 s?1). Measurements included plant height, flower number and major organ dry mass (main and side-shoot stems, main and side-shoot leaves and flowers). To describe the basipetal flowering sequence, a position-dependent growth delay function was introduced into the model. ? The model was calibrated on eight treatments. It was capable of simulating multiple plant phenotypes (flower number, organ biomass, plant height) with visual output. Furthermore, it predicted well the phenotypes of the other eight treatments (validation) through parameter interpolation. ? This model could potentially serve to bridge models of different scales, and to link energy input to crop output in glasshouses.     

Characterization of the effects of inter-tree competition on source–sink balance in Chinese pine trees with the GreenLab model

We investigate the characteristics of individual tree response to competition on source–sink balance through the functional–structural plant model GreenLab. Four Chinese pine (Pinus tabulaeformis Carr.) trees were destructively sampled and were divided into two groups: high-density group and low-density group. First, the effects of density on organ dimensions and on organ relative mass were analysed based on experimental measurements. These were primary indicators of the plant response to competition. Second, the hidden parameters of the GreenLab model, as well as a tree-specific characteristic surface, were estimated using the data of total tree biomass for needle and wood compartments, for each of the four trees in parallel. The quality of the fitting is finally validated using data of individual organ mass at shoot level for the sampled branches. The Mann–Whitney Student’s t test showed that there were significant differences between the shoot attributes of the two groups for shoot diameter, shoot biomass and needle biomass. No significant difference was found for current year shoot lengths of the two groups. The parametric identification of the model allowed estimating and comparing the amount of biomass that was allocated to primary growth and to secondary growth in the two density conditions. It showed that biomass allocated to secondary growth (ring compartment) was the most strongly affected by density, and that the organ demand satisfaction ratio profiles of each of these trees were a relevant, integrated indicator of the tree state.     

闽楠幼树光合特性及生物量分配对光环境的响应

设置100%光环境(L100)、40%光环境(L40)、8%光环境(L8)3种光照梯度,分析万木林闽楠(Phoebe bournei)幼树的光合特性及生物量分配特征对不同光环境的响应。结果表明:(1)闽楠幼树在不同光环境下的最大净光合速率(Pnmax),表观量子效率(AQY),光饱和点(LSP),光补偿点(LCP),暗呼吸速率(Rd)均有显著差异(P<0.05),且随着光照强度的降低,Pnmax,LSP,LCP,Rd随之降低,而AQY却呈现升高的趋势。(2)总生物量、茎生物量、叶生物量、根生物量均表现为L100最大,根冠比、叶生物量比、茎生物量比及根生物量比在3种光环境下无显著差异。(3)闽楠幼树通过改变光合特性,生物量积累来适应光环境的变化,其中光照强度的降低限制了生物量的积累,但并未显著改变生物量地上地下分配比例。闽楠幼树在3种光环境下生物量分配比例并无显著的改变,生物量分配可塑性极低可能是闽楠零散分布的一个重要非人为干扰因素。(4)闽楠幼树所采取的生存策略以地上部分生长为主,光照强度降低时则采取保守策略进行缓慢的资源获取和消耗,全光照条件下采取快速的资源获取和消耗策略。未来造林时可以将闽楠与毛竹(Phyllostachys pubescens)混交来减少郁闭度,促进闽楠幼树的生长。     

Application of the Functional-Structural Tree Model LIGNUM to Sugar Maple Saplings (Acer saccharum Marsh) Growing in Forest Gaps

LIGNUM is a functional-structural model that represents a treeusing four modelling units which closely resemble the real structureof trees: tree segments, tree axes, branching points and buds.Metabolic processes are explicitly related to the structuralunits in which they take place. Here we adapt earlier versionsof LIGNUM designed to model growth of conifers for use withbroad-leaved trees. Two primary changes are involved. First,the tree segment for broad-leaved trees consists of enclosedcylinders of heartwood, sapwood and bark. Leaves consistingof petioles and blades are attached to the segments. Secondly,axillary buds and rules governing their dormancy are includedin the model. This modified version of LIGNUM is used to simulatethe growth and form of sugar maple saplings in forest gaps.The annual growth of the model tree is driven by net productionafter respiration losses are taken into account. The productionrate of each leaf depends on the amount of photosyntheticallyactive radiation it receives. The radiation regime is trackedexplicitly in different parts of the tree crown using a modelof mutual shading of the leaves. Forest gaps are representedby changing the radiation intensity in different parts of themodel sky. This version of LIGNUM modified for use with broad-leaf,deciduous trees and parameterized for sugar maple, yields goodsimulations of growth and form in saplings from different forestgap environments. Copyright 2001 Annals of Botany Company LIGNUM, functional-structural tree model, tree architecture, sugar maple, modelling growth and form     

Performance of trees in forest canopies: explorations with a bottom-up functional-structural plant growth model

Here we present a functional-structural plant model that integrates the growth of metamers into a growing, three-dimensional tree structure, and study the effects of different constraints and strategies on tree performance in different canopies. The tree is a three-dimensional system of connected metamers, and growth is defined by the flush probability of metamers. Tree growth was simulated for different canopy light environments. The result suggest that: the constraints result in an exponential, logistic and decay phase; a mono-layered-leaf crown results from self-shading in a closed canopy; a strong apical control results in slender trees like tall stature species; the interaction between weak apical control and light response results in a crown architecture and performance known from short stature species in closed forest; correlated leaf traits explain interspecific differences in growth, survival and adult stature. The model successfully unravels the interaction effects of different constraints and strategies on tree growth in different canopy light environments.     

Evaluating a non-destructive method for calibrating tree biomass equations derived from tree branching architecture

Key message

Functional branch analysis (FBA) is a promising non-destructive method that can produce accurate tree biomass equations when applied to trees which exhibit fractal branching architecture.

Abstract

Functional branch analysis (FBA) is a promising non-destructive alternative to the standard destructive method of tree biomass equation development. In FBA, a theoretical model of tree branching architecture is calibrated with measurements of tree stems and branches to estimate the coefficients of the biomass equation. In this study, species-specific and mixed-species tree biomass equations were derived from destructive sampling of trees in Western Kenya and compared to tree biomass equations derived non-destructively from FBA. The results indicated that the non-destructive FBA method can produce biomass equations that are similar to, but less accurate than, those derived from standard methods. FBA biomass prediction bias was attributed to the fact that real trees diverged from fractal branching architecture due to highly variable length–diameter relationships of stems and branches and inaccurate scaling relationships for the lengths of tree crowns and trunks assumed under the FBA model.     

Factors controlling resource allocation in mountain birch

We present a comprehensive analysis of factors affecting resource allocation and crown formation in a subarctic birch tree, Betula pubescens ssp. czerepanovii (Orlova) Hämet-Ahti. Using biomass measurements and digitized data on tree architecture, we investigated several hypotheses on various factors that may modify plant growth. We also analyzed the extent to which different mechanisms operate at different scales, ranging from individual shoots to the whole branches or trees. Different factors affected allocation at different levels of organization. Stem age had a minor effect, suggesting that similar control mechanisms operate at all stages of development. Fates of individual shoots were affected by their local growing conditions as indicated, for example, by the dependence of long shoot production on light. Buds formed in the current long shoots were likely to become new long shoots. In the innermost crown parts, radial growth had priority compared to long shoot production. Elongation of individual long shoots was controlled by two conflicting factors. Long distance from the roots suppressed growth, probably indicating costs associated with resource transportation, whereas a high level of light augmented growth. In contrast, growth of entire branches was not so clearly related to the availability of resources, but showed limitation due to allometric scaling. This set a relationship between the maximum long shoot number and the overall branch size, and may indicate allometric constraints to the way a tree is constructed. Strict allometric relationships existed also between other structural traits of mountain birch, most of them similar at all levels of branching hierarchy. However, despite the upper level restrictions set by allometry, source-sink interactions and localized responses of individual shoots operated as local processes that directed allocation towards the most favourable positions. This may be a mechanism for achieving efficient tree architecture in terms of resource intake and costs of transportation.