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• 191. [Article] Computer simulation of animal population dynamics

  Two major objectives were accomplished. 1. A summary of the work done during 1970-71 on a single species intra-specific competition model was written. 2. A multispecies predator-prey model, incorporating ...

  Citation × Citation Citation Abstract Copy Title: Computer simulation of animal population dynamics Author: U.S. International Biological Program. Coniferous Forest Biome, Milne, David M., University of Washington Two major objectives were accomplished. 1. A summary of the work done during 1970-71 on a single species intra-specific competition model was written. 2. A multispecies predator-prey model, incorporating the competition mechanism of the single-species model, was developed almost to completion. The single species model is a computer program that describes the dynamics of a population of insects when food shortages form the only restraint upon population growth. This model deals with energy flow from food through the population's age classes, and simulated reproduction, development, and starvation, as influenced by these flows. Population fluctuations, average densities, and other properties generated by this model correspond closely with results observed in some of the experimental situations and show the need for revision of some model mechanisms in others. The multispecies model currently simulated the Douglas-fir beetle's relation with two predators, the hairy woodpecker and a clerid beetle. This model incorporates the intraspecific competition mechanism mentioned above, a closely analogous interspecific competition mechanism, and the predation mechanisms. Its terminology and data requirements permit any food chain of any number of predaceous species to be investigated. Its design permits an investigator to study various hypotheses regarding the extent to which species omitted from the modeled food chain influence the population changes of the species included in the simulation. The predator/prey model is now complete, but contains mechanical difficulties that have prevented its successful operation thus far. Robert Rydell, in conjunction with Scott Overton, Mary Ann Strand, and I, will attempt to remove these difficulties in the fall of 1971. Title: Computer simulation of animal population dynamics Author: U.S. International Biological Program. Coniferous Forest Biome, Milne, David M., University of Washington Two major objectives were accomplished. 1. A summary of the work done during 1970-71 on a single species intra-specific competition model was written. 2. A multispecies predator-prey model, incorporating the competition mechanism of the single-species model, was developed almost to completion. The single species model is a computer program that describes the dynamics of a population of insects when food shortages form the only restraint upon population growth. This model deals with energy flow from food through the population's age classes, and simulated reproduction, development, and starvation, as influenced by these flows. Population fluctuations, average densities, and other properties generated by this model correspond closely with results observed in some of the experimental situations and show the need for revision of some model mechanisms in others. The multispecies model currently simulated the Douglas-fir beetle's relation with two predators, the hairy woodpecker and a clerid beetle. This model incorporates the intraspecific competition mechanism mentioned above, a closely analogous interspecific competition mechanism, and the predation mechanisms. Its terminology and data requirements permit any food chain of any number of predaceous species to be investigated. Its design permits an investigator to study various hypotheses regarding the extent to which species omitted from the modeled food chain influence the population changes of the species included in the simulation. The predator/prey model is now complete, but contains mechanical difficulties that have prevented its successful operation thus far. Robert Rydell, in conjunction with Scott Overton, Mary Ann Strand, and I, will attempt to remove these difficulties in the fall of 1971. Close

• 192. [Article] A conceptual model of soil mass movement, surface soil erosion, and stream channel erosion processes

  The conceptual framework of an erosion model has been designed to link processes of mass wasting, surface erosion, and channel storage and transport. A program to stimulate mass wasting will be based on ...

  Citation × Citation Citation Abstract Copy Title: A conceptual model of soil mass movement, surface soil erosion, and stream channel erosion processes Author: Fredriksen, R. L., U.S. International Biological Program. Coniferous Forest Biome, Moore, Duane G., Swanston, Douglas N., Dyrness, C. T., University of Washington, Glenn, Leslie Fred, 1944-, Swanson, Frederick J. (Frederick John), 1943-, Cromack, Kermit The conceptual framework of an erosion model has been designed to link processes of mass wasting, surface erosion, and channel storage and transport. A program to stimulate mass wasting will be based on a variation of the factor of safety approach which balances forces tending to drive mass movement against those resisting it. Surface erosion will be treated by using a form of the universal soil loss equation adapted to account for dry ravel processes as well as precipitation generated surface erosion. These processes move material eroded from hillslope landscape areas into the stream channel. Channel erosion may occur either as bedload and suspension load transport or in episodic debris torrents, triggered by debris dam failure or by mass movement from a hillslope. The model will be driven primarily by hydrologic processes and will also receive key inputs from vegetation components of the general ecosystem model. Model development will aim at producing a computer model which will have sufficient realism and predictive capability to be useful to land managers. Title: A conceptual model of soil mass movement, surface soil erosion, and stream channel erosion processes Author: Fredriksen, R. L., U.S. International Biological Program. Coniferous Forest Biome, Moore, Duane G., Swanston, Douglas N., Dyrness, C. T., University of Washington, Glenn, Leslie Fred, 1944-, Swanson, Frederick J. (Frederick John), 1943-, Cromack, Kermit The conceptual framework of an erosion model has been designed to link processes of mass wasting, surface erosion, and channel storage and transport. A program to stimulate mass wasting will be based on a variation of the factor of safety approach which balances forces tending to drive mass movement against those resisting it. Surface erosion will be treated by using a form of the universal soil loss equation adapted to account for dry ravel processes as well as precipitation generated surface erosion. These processes move material eroded from hillslope landscape areas into the stream channel. Channel erosion may occur either as bedload and suspension load transport or in episodic debris torrents, triggered by debris dam failure or by mass movement from a hillslope. The model will be driven primarily by hydrologic processes and will also receive key inputs from vegetation components of the general ecosystem model. Model development will aim at producing a computer model which will have sufficient realism and predictive capability to be useful to land managers. Close