Modelling trees using an object-oriented scheme

Annals of Botany, 1996

The model LIGNUM treats a tree as a collection of a large number of simple units which correspond to the organs of the tree. The model describes the three dimensional structure of the tree crown and defines the growth in terms of the metabolism taking place in these units. The activities of physiological processes can be explicitly related to the tree structures in which they are taking place. The time step is 1 year. The crown of the model tree consists of tree segments, branching points and buds. Each pair of tree segments is separated by a branching point. The buds produce new tree segments, branching points and buds. The tree segments contain wood, bark and foliage. A model tree consisting of simple elements translates conveniently to a list structure : the computer program implementing LIGNUM treats the tree as a collection of lists. The annual growth of the tree is driven by available photosynthetic products after respiration losses are accounted for. The photosynthetic rate of foliage depends on the amount of light. The amount of photosynthates allocated to the growth of new tree segments is controlled by the light conditions and the amount of foliage on the mother tree segment. In principle, the biomass relationships of the tree parts follow the pipe model hypothesis. The orientation of new tree segments results from the application of constant branching angles. LIGNUM has been parametrized for young Scots pine (Pinus syl estris L.) trees. However, the model is generic ; with a change of parameter values and minor modifications it can be applied to other species as well.

Each tree is unique because of the physical environment it experiences over the course of its life. Environmental factors shape a tree within the bounds of its genotype. Only by modeling the environmental influences can we create realistic models of trees. To this end, we constructed a structural simulation that calculates the mass of each branch of the tree to emulate the mechanisms the tree uses to balance its weight, and that estimates the photosynthesis return of the leaves to simulate phototropism. Our effort is motivated by a desire to construct a predictive tool that can be used by both those in computer graphics and forest management, with applications in image synthesis, dendrochronology, mensuration and the simulation of forest succession.

Acta horticulturae, 2011

Studying and developing an integrated understanding fruit tree physiology and growth and development is a difficult endeavor. Plants are very complex organisms that are governed and influenced by a multitude of factors. Traditional experimental approaches to plant function have been largely limited to examining a small number of factors at a time and describing those interactions verbally or with two-or three-dimensional static diagrams. These approaches result in valuable insights into the interactions of a limited number of variables on a similarly limited number of somewhat isolated processes such as organ growth, photosynthesis, or respiration. However it is very difficult to develop and communicate an integrated understanding of natural processes that involve multiple interacting factors. The study and understanding of environmental and endogenous influences on carbon assimilation, partitioning, transport and utilization in plants is a good example of these limitations. The development and testing of hypotheses that explain carbon partitioning and utilization presents complex problems because of the dynamic nature and relationships among carbohydrate partitioning, growth and plant architecture as well as the multitude of factors that can influence each process and organ. One way to dynamically integrate the influence of multiple factors on multiple processes is to use recent advances in computer technology to develop concept-based, computer simulation models of tree crop growth and physiology. For the past two decades research in our laboratories has focused on developing environmental and endogenous influences on carbon assimilation, partitioning, transport and utilization in peach trees. This work has resulted in the PEACH and L-PEACH models. Modeling has allowed us to develop a systematic analysis and integration of hypotheses regarding the factors that control peach fruit growth, crop yield, and tree growth; as well how these processes respond to management practices.

Ecological Modelling, 1998

The model LIGNUM treats a tree as a collection of a large number of simple units that correspond to the organs of a tree. The model describes the three-dimensional structure of the tree crown and derives growth in terms of the metabolism taking place in these units. The time step is one year. The structural units are: tree segments, branching

2020

Introduction : Tree structural and biomass growth studies are mainly carried out on shoot compartment. Root compartment is usually taken apart due to the difficulties on measuring and observing it, especially when considering root growth. AMAP team is already leading experimental studies including both compartments through field experiments and observations. AMAP also provides shoot or root models and simulators of tree architecture and biomass production applied to many agronomic and forest species. It now becomes very critical to study tree structural plasticity according to global climate change. For this purpose, both shoot and root systems have to be considered at the same time since they play collaborative roles dedicated to climate traits (water availability for roots and light or carbon availability for shoots). We propose a whole-plant model and its simulator (RoCoCau) with a linkable external module (TOY) to represent shoot and root compartments dependencies and thus tree ...

Agroforestry Systems, 1995

Modelling plant growth and architecture requires two consecutive and complementary approaches. The first is a qualitative botanical analysis, in which the development sequence of a tree is studied by the identification of various levels of organisation and of homogeneous subunits. All of these-architectural unit, axis, growth unit-follow particular growth processes which can be described by using the second approach, the quantitative analysis. Modelling of the functioning of meristems based upon stochastic processes has been carried out since 1980, in combination with a large amount of experimental work on temperate and tropical plants. Calculations involved in tree simulations from field data are based upon the probabilistic Monte Carlo method for the topological part and on analytical geometry for the morphological part. Computer graphics methods are then used to visualise the computed plant. Several sectors in agroforestry are concerned with application of such plant architecture modelling: tree growth and yield, radiative transfers, timber quality and mechanics, simulation of competition, interaction between plant morphology and physiology.

Frontis, 2007

Carbohydrate partitioning is closely coupled with plant growth and architecture, and therefore constitutes an important aspect of the functional-structural modelling of plants. L-PEACH is an L-systembased tree simulation model that combines supply/demand concepts of carbon partitioning with a developmental model of tree architecture. The model is expressed in terms of modules that represent plant organs. An organ may correspond to one or more elementary sources or sinks for carbohydrates. The whole plant is modelled as a branching network of these sources and sinks, connected by conductive elements. An analogy to an electric network is used to calculate the flow and partitioning of carbohydrates between the individual components. It can simulate multiple years of tree growth while capturing the effects of irrigation, crop load and pruning on carbon partitioning and the dynamics of architectural development. The growing tree can be visualized in a schematic or semi-realistic manner, while quantitative data characterizing individual organs, organ types or the whole tree can be output for visualization and analysis to an external program, such as MATLAB.

Forest Ecology and Management, 1999

A simulation approach is used to describe annual tree growth and tree mortality from the output of a physiologically based model (FORSANA). Height and diameter growth are calculated directly from the amount of carbon allocated to sapwood by considering an optimum height/diameter ratio, which depends on stand density. Tree mortality is de®ned by means of a relation between net primary production and carbon loss due to compartment senescence. Thus, all responses to environmental conditions considered in the physiological part of the model are implicitly considered in the stand development description. The dynamic simulation of stand properties, on the other hand, is required to apply the physiological based process description to long-term assessments. The model is used to describe height and diameter development of three Scots pine (Pinus sylvestris L.) stands in eastern Germany which are exposed to different levels of nitrogen deposition and SO 2 air pollution. Results are compared with tree ring analysis covering a period of 27 years. For further evaluation, the model is initialised with forest inventory data of 288 pine stands and is run over 23 years using daily weather and deposition data as well as fertilisation information as input. The results are compared to data from a second inventory of the same stands. This comparison is conducted separately for regions exposed to high and low deposition. The model represents annual height and diameter development at two of the three selected sites. With respect to the third site, considerable disturbances in the early years of stand development are assumed to be responsible for the unusual growth trend. The regional evaluation of the model yields correlation coef®cients with forest inventory data between 0.57 and 0.86, with a generally better ®t on diameter and stemwood volume than height. The approach demonstrates the uncertainty of estimations which are based on investigations at only few sites, and is discussed as a possible method for regional assessment of forest development under environmental change.

2000

Tree profile or taper models are an important component of decision support systems for forest management. An extensive body of theory and observations on the mechanisms of tree form development has accumulated over the last 150 years. Quantitative mensurational models, however, have made little use of that information. Taper models remain largely empirical and static, describing tree dimensions and shape at one point in time. Here taper equations are derived from simplified models of radial stem growth consistent with physiological knowledge. It is expected that this approach may improve accuracy, especially when stands are subjected to varied density management alternatives. Keywords: taper, tree growth, pipe model [R package: https://cran.r-project.org/package=dyntaper]