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Hybrid ecosystem-level forest models as tools for forest management and research Blanco J.A. 1,2 , Kimmins J.P. 1 , Seely B. 1 , Welham C. 1 , Scoullar K. 3 1 Dep. Forest Sciences, Faculty of Forestry, The University of British Columbia, 3041-2424 Main Mall, V6T 1Z4, Vancouver, B.C. 2 Contact: [email protected] 3 Life Science Programming Ltd., Naramata, B.C. WHY ECOSYSTEM WHY ECOSYSTEM - - LEVEL MODELS? LEVEL MODELS? Levels of biological Levels of biological organization organization Levels of biological Levels of biological integration integration Ecosystem Ecosystem Understanding and Understanding and Prediction Prediction Prediction Prediction Prediction Prediction Prediction Prediction Ecosystem Ecosystem Community Community Understanding Understanding Population Population Understanding Understanding Individual Individual Understanding Understanding and and Prediction Prediction Prediction Prediction Prediction Prediction Prediction Prediction Individual Individual Organ systems Organ systems Understanding Understanding Organs, tissues Organs, tissues Understanding Understanding Cell Cell Understanding and Understanding and Prediction Prediction Prediction Prediction Prediction Prediction Prediction Prediction Cell Cell Sub Sub - - cellular cellular Understanding Understanding Function of level Prediction: The need for ecosystem level Prediction: The need for ecosystem level Biological knowledge is organized into levels of biological organization that are indispensable for the description and understanding of events and conditions at each of these levels. However, prediction of future events and conditions at any of these levels can only be successful in the context of the next level of biological integration above (Rowe 1961). Individual levels of biological organization define only a subset of the processes that affect future conditions and events at that level. Only the next true level of integration above in the hierarchy of system complexity defines the key determinants of the future for the level of interest. Thus, the fate of an individual organism cannot be defined solely on the basis of knowledge of the biology of that individual, or of the population or even of the biotic community in which it finds itself. The population level fails to identify all the biotic factors influencing that individual, and neither the population nor the community level address the climatic and edaphic factors and the physical natural disturbance events that play such a key role in defining the future for that individual (Kimmins et al. 2005). REFERENCES Kimmins J.P., Mailly D., Seely B. 1999. Modelling forest ecosystem net primary production: the hybrid simulation approach used in FORECAST. Ecol. Model. 122, 195-224. Kimmins J.P., Welham C., Seely B., Meitner M., Rempel R., Sullivan T. 2005. Science in forestry: Why does it sometimes disappoint or even fail us? T. For. Chron. 81, 723-734. Rowe J.S. 1961. The level-of-integration concept and ecology. Ecology 42, 420–427. Seely B., Nelson J., Wells R., Peter B., Meitner M., Anderson A., Harshaw H., Sheppard S., Bunnell F.L., Kimmins H., Harrison D. 2004. The application of a hierarchical, decision-support system to evaluate multiobjective forest management strategies: a case study in north-eastern British Columbia, Canada. THE FAMILY OF MODELS developed by THE FOREST ECOSYSTEM THE FAMILY OF MODELS developed by THE FOREST ECOSYSTEM MANAGEMENT SIMULATION GROUP at UBC MANAGEMENT SIMULATION GROUP at UBC FORECAST user interface FORECAST FORECAST Hybrid model: It uses historical/field growth data to simulate future growth & yield. This simulated growth is modified by some biological processes: - light competition - nutrient availability Non-spatial stand-level model: It does not account for individual stems and tree positions in the stand, but it does have a tree list and tracks individual stem sizes Ecosystem management model: It simulates interactions between ecosystem component (trees, minor vegetation - shrubs, herbs, bryophytes - and the soil) and the influence of different management practices and natural disturbances on them. FORECAST graphical output a. Harvest map with underlying forest types / conditions b. Regeneration pixel groups c. Light ecotones a. b. c. Trees Ecotone Open 0 100 200 300 400 0 100 200 300 400 m m Example of 16 ha block LLEMS LLEMS Hybrid model: It will uses FORECAST to estimate key ecosystem processes (light & nutrient competition). Spatial (raster-based) stand-level model: Individual 10x10 plots (pixels) are simulated by FORECAST, including individual tree list information. There is between-pixel interaction in terms of light, litterfall and seed dispersal, and windthrow risk. Landscape ecosystem-level ecosystem: It will allow the user to explore alternative VR systems by projecting the spatial and temporal development of complex cut blocks created by partial harvesting in areas ranging from 20 to 2000 ha FORCEE FORCEE Hybrid model: It uses FORECAST to estimate key ecosystem processes (light & nutrient competition). Spatially-explicit individual tree simulator: It simulates individual trees and plants, their spatial position and effects on light, forest floor and nutrient availability, and creates a light and soil "footprint“ for each tree. Ecosystem-level ecosystem: It simulates interactions between different ecosystem components as trees, understory, bryophytes and soil an the influences of different management practices on them. FORCEE user interface Possible Possible Forest Forest Futures (PFF) Futures (PFF) Hybrid model: It uses FORECAST to estimate ecosystem key processes. Non-spatial watershed-level model: Management scenario analysis tool for education, extension and management gaming. PFF user interface ForWaDy ForWaDy Stand-level model: Simulation of hydrological fluxes and generalized energy balance. Multi layered representation of vertical fluxes in a daily time step. New hydrological submodel for FORECAST, with feedback on growth rates and decomposition rates. Developed using the Stella ® modelling framework WHY HYBRID MODELS? WHY HYBRID MODELS? Model output is only valid if: The future growing conditions are sufficiently similar to those that existed during the development of the sample stands on which the models are based yield time Past Present Better growing conditions Similar growing conditions Poorer growing conditions harvest Future? Models under a changing future Models under a changing future ‘Historical bioassay’ models based on experience are valid for the species involved and the particular set of biotic and abiotic growth conditions that pertained over the period of growth. However, if changes in future management regimes or human impacts on the biophysical environment significantly alter future growth conditions, the predictions of the bioassay are unlikely to be accurate. Process-based models empirically derived from relationships between a series of independent variables and tree growth have great heuristic value, but most of them are not ecosystem-level models and are rarely used in practical applications in forestry, primarily because we do not know enough about the key ecosystem processes and their interactions to make accurate predictions. A third, ‘hybrid’ approach has been developed which attempts to combine the strengths of the other two approaches and thereby compensate for their individual weaknesses. These models take the yield predictions from a historical bioassay model or raw field data and modify them according to a simulation of the temporal variation in available light and nutrients (Kimmins et al. 1999). Projection Projection Interpretation Interpretation Forest Forest - - level Timber Supply Model level Timber Supply Model (ATLAS) (ATLAS) Wildlife Habitat Supply Model Wildlife Habitat Supply Model ( ( SimFor SimFor ) ) Polygon Polygon - - Based Based Raster Raster - - Based Based HIERARCHICAL DECISION SUPPORT SYSTEMS HIERARCHICAL DECISION SUPPORT SYSTEMS Select Select treatment treatment Stand Stand - - Level Model Level Model (FORECAST) (FORECAST) Stand Stand - - Level Visualization Model Level Visualization Model (SVS) (SVS) Landscape Landscape - - Level Visualization Model Level Visualization Model (CALP Forester) (CALP Forester) Non Non - - Spatial Spatial Visualization Visualization Individual trees represented Individual trees represented Links between models Links between models The multi-resource nature of modern forestry demands that managers assess the potential impacts of their decisions on a broad range of forest attributes related to biodiversity, timber production, carbon storage, recreation and other values. The hierarchical structure facilitates problem analysis across different planning levels (i.e tactical vs. strategic) by allowing for the addition of complexity where warranted and necessary. Moreover, the modular approach allows for increased flexibility within a DSS as it facilitates the use of different models to address specific problems or ecosystem types (Seely et al 2004). Individual trees or stands represented Individual trees or stands represented
