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Title: Simulation of forest ecosystem dynamics, with respect to the problem of hierarchy
Author: Luan, Jingsheng
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1994
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As knowledge about forest ecosystems accumulates, it becomes important to develop an explicit description of the functional relationships between processes. These relationships include processes ranging from cell to leaf, tree and forest. Knowledge obtained at any one of these levels cannot provide much understanding or predictive power, because the overall behaviour is influenced by positive and negative feedback between levels. A hierarchical approach is applied for coupling processes at these levels. In this study, a hierarchical forest model FORDYN is developed, which can integrate knowledge at a biochemical or physiological level to make statements on tree growth and forest succession levels. This procedure is referred to as 'scaling up'. The model FORDYN consists of four levels of processes characterised by the time step or behaviour frequency. In level 1, a forest succession process is described by accounting the fate of spatially distributed individual trees in an annual time step. In level 2, each tree' growth is represented by a 'process-based' approach, whereby assimilation, assimilate allocation, nitrogen dynamics and water balance are accounted for in a daily time step during tree growth. In level 3, daily photosynthesis is accumulated by hourly value by a 3-point Gaussian scheme. In level 4, instantaneously CO2 assimilation rate is calculated by a biochemical (mechanistic) photosynthesis model. To exploit fully the hierarchical feature of the model structure, FORDYN is designed to be used in different simulation modes to meet the demand of different purposes of users. FORDYN was tested against the common data set provided by the European Pine Modelling group, and sensitivity analysis of this model was compared with other published and validated European pines models. It was shown that FORDYN is robust and responsive. FORDYN has been used to analyse current problems of global change, such as the impact of CO2 increase. It was shown that this model can provide new insights into ecosystem dynamics and environmental problems of wide concern. This is probably the first ecological model at can simulate long term forest development by scaling up biochemical processes, physiological processes, and tree growth processes. It is a contribution to the modelling methodology in forest modelling, also it provides a good example of unifying ecosystem science and population biology.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available