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An ecological model for the management of natural forests derived from the Tropenbos permanent sample plots at Pibiri, Guyana June 2002

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  • Tropenbos International
... The Silviculture and Yield Management for Tropical Forests (SYMFOR) is a modeling framework that combines a management model, which allows the user to specify silvicultural activities in mixed tropical forest (e.g., harvest, thinning, poisoning, enrichment planting), with an empirical spatially explicit individual tree-based ecological model, which simulates the natural processes of recruitment, growth and mortality. The SYMFOR model, originally designed for use in Indonesia (Phillips et al., 2003), was adapted for use in Guyana (Phillips et al. 2002b) and then for the Brazilian Amazon . In Brazil, the model was further adapted by incorporating new management options and translating the user interface into ...
... SYMFOR is a software framework for ecological and management models relating to species rich tropical forests (Phillips & van Gardingen 2001a, 2001b, Phillips et al. 2002. Models within SYMFOR have been applied in Indonesia and Guyana to analyse the sustainability of alternative management scenarios (van Phillips et al. 2003, van Gardingen et al. 2003, chapter 4). ...
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Population dynamics models for tropical rain forests rarely include detailed descriptions of regeneration. In this chapter we describe models for juvenile tree (seedlings and saplings < 2 cm DBH) growth and juvenile mortality that were included in a forest simulation model that also includes seed production, seed dispersal and germination. Growth of juvenile trees in relation to competition index was very variable. Many seedlings showed reductions in stem height that are not related to light availability, but probably are the result of falling debris, browsing, herbivory and dieback due to pathogens and pests. These effects can be regarded as rather stochastic processes (from a seedling's point of view). Therefore we developed a modelling approach that can accommodate stochastic variation in growth and temporal auto-correlation. We then evaluate the significance of stochastic variation and auto-correlation for the fraction of recruits that will successfully recruit to 2 cm DBH using simulated growth trajectories and explore the differences between nine functional groups of species. Faster growing seedlings had a higher probability to survive the time needed to reach 2 cm DBH than slower growing seedlings from the same functional group. Hence the seedlings that reach a size of 2 cm DBH on average have grown faster than the other seedlings. In a traditional modelling approach, however, all seedlings that grow at a certain light availability grow according the average of all seedlings at that light availability. Thus seedlings that normally would grow faster (by chance) and reach 2 cm DBH will then grow slower, which reduces their survivorship and vice versa for individuals that normally grow slower because of a random reduction in stem height for instance. Inclusion of the stochastic variation in growth resulted in two clear patterns. For functional groups that had a relatively slow growth rate in relation to their annual mortality probability the inclusion of stochastic mortality resulted in a higher survivorship (increased fraction of the individuals reached 2 cm DBH) than with the average model, while functional groups that had a relatively fast growth rate in relation to their annual mortality probability showed the opposite pattern (decreased survivorship). Hence, allowing stochastic variation in growth rates has important consequences and leads to significantly different results than the average model. Total auto-correlation did significantly affect these patterns, but the degree of auto-correlation comparable with field data had no major affect on the model results. Estimated mean ages for juveniles at 2 cm DBH, based on the growth trajectories including stochastic variation in growth and including mortality, ranged from 7 years for small pioneers to 68 years for the understorey climax group. The 2.5 % fastest growing juveniles reached a size of 2 cm DBH already at 4 and at 45 years, respectively.
... Similar work has been carried out for African forests in Uganda and Ghana using approaches described by Alder (Alder, 1995;Alder et al., 2001). In addition to the SYMFOR ecological model for Indonesia (Phillips et al., 2002b), there are also models for Guyana (Phillips et al., 2002c) and Brazil (Phillips et al., 2002a). Further developments are likely and will be published as SYMFOR technical notes (http://www.symfor.org/technical). ...
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This document is an output from a project funded through the Forestry Research Programme of the UK Department for International Development (DFID) for the benefit of developing countries. The views expressed are not necessarily those of DFID. R6915 Forestry Research Programme.
... The classified category was the area potentially available to each tree, calculated by sharing the total plot area among the trees according to their size. Competition indices included absolute variables such as stand density and basal area (Ong & Kleine 1995), and competition environment for each tree in the plot, overtopping basal area, diameter independent competition index and over-topping shade index (Phillips & van Gardingen 2001b). Topographic features and environmental variables used in the growth model included site-specific factors (e.g. ...
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This paper examines the diameter growth of planted Dryobalanops sumatrensis based on the results of measurements for all trees with diameter ≥ 10 cm collected between 1997 and 2000. The study was carried out at Bukit Lagong Forest Reserve, Selangor, Peninsular Malaysia. Least square method using transformed and weighted models was developed to relate periodic annual diameter increment to diameter, competition indices and environmental factors as independent variables. The results indicated that transformed model relating periodic annual diameter increment to diameter, competition indices (basal area and over-topping basal area) and environmental variables (elevation and slope) explained a significant proportion of the variation in the periodic annual diameter increment at 36.7% (p < 0.05). Overall results of the modelling were negatively biased and underestimated the predicted periodic annual diameter increments of the species.
... SYMFOR is a modelling framework that combines a management model, allowing the user to specify silvicultural activities in mixed tropical forest (e.g., harvest, thinning, poisoning, enrichment planting), with an empirical spatially explicit individual tree-based ecological model, which simulates the natural processes of recruitment, growth and mortality. The SYMFOR model, originally designed for use in Indonesia (Phillips et al., 2003), was adapted for use in Guyana (Phillips et al., 2002) and then in the Brazilian Amazon (Phillips et al., 2004). In Brazil the model was further adapted by incorporating new management options and translating it into Portuguese to become the model SIMFLORA. ...
Article
Timber logging is one of the main land uses in the Brazilian Amazon. Despite its recognized potential as a sustainable activity, logging is generally conducted in an unsustainable or predatory manner, with significant negative environmental impact. There is increasing pressure to adopt more sustainable practices and reduced-impact logging (RIL) is gaining acceptance as a more environmentally benign alternative to unplanned, conventional logging (CL). Comparisons of these two harvest systems have largely focused on differences in efficiency (financial) and immediate impacts on stand structure, residual timber stocks and the physical environment.
... In Bolivia, a simulation model based on diameter distribution, increment and natural mean mortality of commercial species was developed, revealing that complete volume recovery will not be possible under currently prescribed cutting cycles and minimum felling diameter (Dauber et al., 2005). The SYMFOR model originally designed for use in Indonesia (Phillips et al., 2003) was adapted for use in Guyana (Phillips et al., 2002a) and then the Brazilian Amazon (Phillips et al., 2004). This model for Brazil was further adapted for use in this study with the incorporation of new management options and translation into Portuguese to become the model SIMFLORA. ...
Article
The sustainability of a range of forest management scenarios were evaluated for the Tapajós region of the Brazilian Amazon using the growth and yield simulation model, Simflora, a derivative of the model SYMFOR developed for application in Indonesia. A simulation of current management regulations based upon a maximum extracted volume of 35 m3 ha−1 and a 30-year cutting cycle was found to be unsustainable. A range of alternative specifications for the control (regulation) of harvested timber yield were compared, along with associated estimates of timber increment and description of the ecological composition of the stand. The alternative scenarios included cutting cycles ranging from 10 to 60 years and maximum yields from 10 to 40 m3 ha−1.
Article
The sustainable management of areas of logged-over tropical forests requires an understanding of the potential yield from the forest and likely financial performance of the management system. This paper describes an analytical approach that involves the linkage of a simulation model of forest growth and yield to a financial model based on data from a forest concession in East Kalimantan (Indonesian Borneo). The growth and yield model SYMFOR (silviculture and yield management for tropical forests) was linked to a financial model derived for a forest concession managed under the Indonesian selective logging and replanting system (TPTI). This combined approach was used in this study to predict the likely timber yield for contrasting management regimes and then to calculate estimates of the financial performance described as the internal rate of return (IRR) and net present value (NPV) of the forest estate.
Article
A model of ecological processes that determine the behaviour of individual trees, and thus the overall characteristics of forest stands, is described, evaluated and discussed. The purpose of the model is to simulate individual trees as part of the SYMFOR framework for modelling the effects of silviculture on the growth and yield of tropical forests. The model encompasses the response of individual trees to a range of conditions, described in a spatially explicit form, that represent typical situations occurring in forests at all stages following management interventions. The model describes the processes governing the behaviour of trees, allowing it to be used with validity for simulations of management regimes that do not have experimental precedent. The model can thus guide or negate the requirement for lengthy and laborious field trials. Sub-models of tree growth, natural mortality and recruitment processes specify the ecological model. The growth model describes the annual diameter increment for an individual tree, calculated from a deterministic component using tree diameter, local competition (5 m radius), wider competition (30 m radius) and the effect of previous harvesting and a stochastic component representing the remaining variation. The mortality model represents the death of trees as a probability function that increases with diameter. Damage from falling trees is represented by a trapezium-shaped area in which all trees smaller than the falling tree are killed. The recruitment model uses 10 by 10 m2 grid-squares to represent the probability of recruitment of trees past the 10 cm diameter threshold of the SYMFOR framework based upon the average competition within a grid-square. The whole model is derived from data and does not rely on theories of tree or forest behaviour, but all aspects represent real forest processes.
SYMFOR: a tool for sustainable forest management
  • P R Van Gardingen
  • P D Phillips
  • Y Laumonier
van Gardingen, P.R. and Phillips, P.D., 1998. SYMFOR: a tool for sustainable forest management. In: Laumonier, Y., Proceedings of the EU_FIMP/INTAG international conference on data management and modelling using remote sensing and GIS for tropical forest land inventory, Jakarta, Indonesia, 473-490.
Development of Modelling Objectives, Guyana: Back to Office Report. The University of Edinburgh, Edinburgh, 30 pgs Plant diversity in Guyana: with recommendations for a protected areas strategy
  • P D Phillips
Phillips, P.D., 2001. Development of Modelling Objectives, Guyana: Back to Office Report. The University of Edinburgh, Edinburgh, 30 pgs. http://www.symfor.org/btor/Guyana_jun01.pdf ter Steege, H., 2000. Plant diversity in Guyana: with recommendations for a protected areas strategy. Tropenbos Series 18, Tropenbos Foundation, Wageningen, Netherlands.
Project Memorandum (Exit Strategy) FRP project R6915
  • P R Van Gardingen
van Gardingen, P.R., 2001a. Project Memorandum (Exit Strategy) FRP project R6915. The University of Edinburgh, Edinburgh, 89 pgs.
The SYMFOR framework for individual-based spatial ecological and silvicultural forest models
  • P D Phillips
  • P R Van Gardingen
Phillips, P.D. and van Gardingen, P.R., 2001b. The SYMFOR framework for individual-based spatial ecological and silvicultural forest models. SYMFOR Technical Notes Series No. 8, The University of Edinburgh. http://www.symfor.org/technical/framework.pdf
On: The low levels of natural damage observed in forests in Guyana
  • N Bird
Bird, N., 2001. On: The low levels of natural damage observed in forests in Guyana. Pers. Comm.