I am a conservation biologist, broadly trained in theoretical ecology. Although I am no longer actively engaged in research, my research program focused on the use of computer simulation modeling to address issues concerned with biodiversity conservation and invasive species control.
Population viability analysis, the use of ecological models to assess a population's risk of... more Population viability analysis, the use of ecological models to assess a population's risk of extinction, plays an important role in contemporary conservation biology. The premise of this review is that models, concepts, and data analyses that yield results on extinction risk of threatened and endangered species can also tell us about establishment risks of potentially invasive species. I briefly review important results for simple unstructured models, demographic models, and spatial models, giving examples of the application of each type of model to invasive species, and general conclusions about the applicability of each type of model to risk analysis for invasive species. The examples illustrate a portion of the range of potential applications of such models to invasive species, and some of the types of predictions that they can provide. They also highlight some of the limitations of such models. Finally, I present several conjectures and open research questions concerning th...
independent scientific input into the formulation of methods and processes for risk assessment of... more independent scientific input into the formulation of methods and processes for risk assessment of invasive species. In breakout sessions on (1) the effects of invasive species on human health, (2) effects on plants and animals, (3) risk analysis issues and research needs related to entry and establishment of invasive species, and (4) risk analysis issues and research needs related to the spread and impacts of invasive species, workshop participants discussed an overall approach to risk assessment for invasive species. Workshop participants agreed on the need for empirical research on areas in which data are lacking, including potential invasive species, native species and habitats that may be impacted by invasive species, important biological processes and phenomena such as dispersal, and pathways of entry and spread for invasive species. Participants agreed that theoretical ecology can inform the process of risk assessment for invasive species by providing guidelines and conceptual...
Titles found within Poster Session-Extended Abstracts include:Assessment of emergency fire rehabi... more Titles found within Poster Session-Extended Abstracts include:Assessment of emergency fire rehabilitation of four fires from the 2000 fire season on the Vale, Oregon, BLM district: review of the density sampling materials and methods: p. 329Ā Growth of regreen, seeded for erosion control, in the Manter fire area, southern Sierra Nevada: p. 330Ā Classification of wildland fire effects in silviculturally treated vs. untreated forest stands of New Mexico and Arizona: p. 332The potential for smoke to ventilate from wildland fires in the United States: p. 334Ā Effects of fire and mowing on expansion of reestablished black-tailed prairie dog colonies in Chihuahuan desert grassland: p. 335Data collection and fire modeling determine potential for the use of PlateauĀ® to establish fuelbreaks in cheatgrass-dominated rangelands: p. 340Ā Debris flow occurrence in the immediate postfire and interfire periods and associated effects on channel aggradation in the Oregon coast Range: p. 342Ā LANDFIRE: ma...
The pale fox (Vulpes pallida) is a small, little known African carnivore that is patchily distrib... more The pale fox (Vulpes pallida) is a small, little known African carnivore that is patchily distributed throughout the Sahel. We studied the food habits of pale foxes in the Termit and Tin Toumma National Nature Reserve in south-eastern Niger by examining the frequency of occurrence and proportions of prey remains in scats (nĀ =Ā 398). Arthropods, primarily Coleoptera, Orthoptera and Scorpiones, were present in 91.8% of scats. Mammalian remains, primarily Gerbillus spp., were found in 5.6% of scats. Avian, squamate and plant material were rarely present. There was little evidence of seasonal variation in the frequency of occurrence or proportions of prey in the diet, confirming that pale foxes are primarily insectivorous.
... List of contributors, Part I. Introduction: 1. Impact of a classic paper by H. Ronald Pulliam... more ... List of contributors, Part I. Introduction: 1. Impact of a classic paper by H. Ronald Pulliam: the first 20 years Vanessa Hull, Anita T ... Scott M. Pearson and Jennifer M. Fraterrigo, 7. When sinks rescue sources in dynamic environments Matthew R. Falcy and Brent J. Danielson, 8 ...
ABSTRACT: Populations live in habitats whose quality varies spatially and temporally. Understandi... more ABSTRACT: Populations live in habitats whose quality varies spatially and temporally. Understanding how populations deal with these variable habitats can aid our understanding of theoretical issues, and practical issues of biological invasions and biodiversity conservation. I investigate these issues by superimposing simple models of population growth and dispersal on spatiotemporally fractal landscapes, and examining the properties of the landscapes, and of the populations inhabiting them. The properties of the simulated landscape sequences are comparable to those of real habitats. The simulated populations exhibit a range of dynamic behaviors; these behaviors are strongly influenced by the fractal parameters of the landscapes. The results may help explain several important phenomena seen in reintroductions of threatened and endangered species, introductions of biological control agents, and biological invasions. These phenomena include frequently observed lags between population i...
We modeled current and future distribution of suitable habitat for the talus-obligate montane mam... more We modeled current and future distribution of suitable habitat for the talus-obligate montane mammal Ochotona princeps (American pika) across the western USA under increases in temperature associated with contemporary climate change, to: a) compare forecasts using only climate variables vs using those plus habitat considerations; b) identify possible patterns of range collapse (center vs margins, and large- vs small-sized patches); and c) compare conservation and management implications of changes at two taxonomic resolutions, and using binned- vs binary-probability maps. We used MaxEnt to analyze relationships between occurrence records and climatic variables to develop a bioclimatic-envelope model, which we refined by masking with a deductive appropriate-habitat filter based on suitable land-cover types. We used this final species-distribution model to predict distribution of suitable habitat under range-wide temperature increases from 1 to 7Ā°C, in 1Ā°C increments; we also compared these results to distribution under IPCC-forecasted climates for 2050 and 2080. Though all currently recognized lineages and traditionally defined subspecies were predicted to lose increasing amounts of habitat as temperatures rose, the most-dramatic range losses were predicted to occur among traditional subspecies. Nineteen of the 31 traditional US pika subspecies were predicted to lose > 98% of their suitable habitat under a 7ĖC increase in the mean temperature of the warmest quarter of the year, and lineages were predicted to lose 88 95% of suitable habitat. Under a 4ĖC increase, traditional subspecies averaged a predicted 73% (range = 44ā99%) reduction. The appropriate-habitat filter removed 40ā6% of the predicted climatically suitable pixels, in a stepped and monotonically decreasing fashion as predicted temperatures rose. Predicted range collapse proceeded until only populations in island-biogeographic āmainlandsā remained, which were not in the geographic range center. We used this model system to illustrate possible distributional shifts under stepped changes in biologically relevant aspects of climate, importance of land cover and taxonomic level in species-distribution forecasts, and impact of using a single threshold vs multiple categories of persistence probability in predicted range maps; we encourage additional research to further investigate the generality of these patterns.
Source: In: Narog, Marcia G., tech. coord. Proceedings of the 2002 Fire Conference: Managing fire... more Source: In: Narog, Marcia G., tech. coord. Proceedings of the 2002 Fire Conference: Managing fire and fuels in the remaining wildlands and open spaces of the Southwestern United States. Gen. Tech. Rep. PSW-GTR-189. Albany, CA: US Department of Agriculture, ...
Population viability analysis, the use of ecological models to assess a population's risk of... more Population viability analysis, the use of ecological models to assess a population's risk of extinction, plays an important role in contemporary conservation biology. The premise of this review is that models, concepts, and data analyses that yield results on extinction risk of threatened and endangered species can also tell us about establishment risks of potentially invasive species. I briefly review important results for simple unstructured models, demographic models, and spatial models, giving examples of the application of each type of model to invasive species, and general conclusions about the applicability of each type of model to risk analysis for invasive species. The examples illustrate a portion of the range of potential applications of such models to invasive species, and some of the types of predictions that they can provide. They also highlight some of the limitations of such models. Finally, I present several conjectures and open research questions concerning th...
independent scientific input into the formulation of methods and processes for risk assessment of... more independent scientific input into the formulation of methods and processes for risk assessment of invasive species. In breakout sessions on (1) the effects of invasive species on human health, (2) effects on plants and animals, (3) risk analysis issues and research needs related to entry and establishment of invasive species, and (4) risk analysis issues and research needs related to the spread and impacts of invasive species, workshop participants discussed an overall approach to risk assessment for invasive species. Workshop participants agreed on the need for empirical research on areas in which data are lacking, including potential invasive species, native species and habitats that may be impacted by invasive species, important biological processes and phenomena such as dispersal, and pathways of entry and spread for invasive species. Participants agreed that theoretical ecology can inform the process of risk assessment for invasive species by providing guidelines and conceptual...
Titles found within Poster Session-Extended Abstracts include:Assessment of emergency fire rehabi... more Titles found within Poster Session-Extended Abstracts include:Assessment of emergency fire rehabilitation of four fires from the 2000 fire season on the Vale, Oregon, BLM district: review of the density sampling materials and methods: p. 329Ā Growth of regreen, seeded for erosion control, in the Manter fire area, southern Sierra Nevada: p. 330Ā Classification of wildland fire effects in silviculturally treated vs. untreated forest stands of New Mexico and Arizona: p. 332The potential for smoke to ventilate from wildland fires in the United States: p. 334Ā Effects of fire and mowing on expansion of reestablished black-tailed prairie dog colonies in Chihuahuan desert grassland: p. 335Data collection and fire modeling determine potential for the use of PlateauĀ® to establish fuelbreaks in cheatgrass-dominated rangelands: p. 340Ā Debris flow occurrence in the immediate postfire and interfire periods and associated effects on channel aggradation in the Oregon coast Range: p. 342Ā LANDFIRE: ma...
The pale fox (Vulpes pallida) is a small, little known African carnivore that is patchily distrib... more The pale fox (Vulpes pallida) is a small, little known African carnivore that is patchily distributed throughout the Sahel. We studied the food habits of pale foxes in the Termit and Tin Toumma National Nature Reserve in south-eastern Niger by examining the frequency of occurrence and proportions of prey remains in scats (nĀ =Ā 398). Arthropods, primarily Coleoptera, Orthoptera and Scorpiones, were present in 91.8% of scats. Mammalian remains, primarily Gerbillus spp., were found in 5.6% of scats. Avian, squamate and plant material were rarely present. There was little evidence of seasonal variation in the frequency of occurrence or proportions of prey in the diet, confirming that pale foxes are primarily insectivorous.
... List of contributors, Part I. Introduction: 1. Impact of a classic paper by H. Ronald Pulliam... more ... List of contributors, Part I. Introduction: 1. Impact of a classic paper by H. Ronald Pulliam: the first 20 years Vanessa Hull, Anita T ... Scott M. Pearson and Jennifer M. Fraterrigo, 7. When sinks rescue sources in dynamic environments Matthew R. Falcy and Brent J. Danielson, 8 ...
ABSTRACT: Populations live in habitats whose quality varies spatially and temporally. Understandi... more ABSTRACT: Populations live in habitats whose quality varies spatially and temporally. Understanding how populations deal with these variable habitats can aid our understanding of theoretical issues, and practical issues of biological invasions and biodiversity conservation. I investigate these issues by superimposing simple models of population growth and dispersal on spatiotemporally fractal landscapes, and examining the properties of the landscapes, and of the populations inhabiting them. The properties of the simulated landscape sequences are comparable to those of real habitats. The simulated populations exhibit a range of dynamic behaviors; these behaviors are strongly influenced by the fractal parameters of the landscapes. The results may help explain several important phenomena seen in reintroductions of threatened and endangered species, introductions of biological control agents, and biological invasions. These phenomena include frequently observed lags between population i...
We modeled current and future distribution of suitable habitat for the talus-obligate montane mam... more We modeled current and future distribution of suitable habitat for the talus-obligate montane mammal Ochotona princeps (American pika) across the western USA under increases in temperature associated with contemporary climate change, to: a) compare forecasts using only climate variables vs using those plus habitat considerations; b) identify possible patterns of range collapse (center vs margins, and large- vs small-sized patches); and c) compare conservation and management implications of changes at two taxonomic resolutions, and using binned- vs binary-probability maps. We used MaxEnt to analyze relationships between occurrence records and climatic variables to develop a bioclimatic-envelope model, which we refined by masking with a deductive appropriate-habitat filter based on suitable land-cover types. We used this final species-distribution model to predict distribution of suitable habitat under range-wide temperature increases from 1 to 7Ā°C, in 1Ā°C increments; we also compared these results to distribution under IPCC-forecasted climates for 2050 and 2080. Though all currently recognized lineages and traditionally defined subspecies were predicted to lose increasing amounts of habitat as temperatures rose, the most-dramatic range losses were predicted to occur among traditional subspecies. Nineteen of the 31 traditional US pika subspecies were predicted to lose > 98% of their suitable habitat under a 7ĖC increase in the mean temperature of the warmest quarter of the year, and lineages were predicted to lose 88 95% of suitable habitat. Under a 4ĖC increase, traditional subspecies averaged a predicted 73% (range = 44ā99%) reduction. The appropriate-habitat filter removed 40ā6% of the predicted climatically suitable pixels, in a stepped and monotonically decreasing fashion as predicted temperatures rose. Predicted range collapse proceeded until only populations in island-biogeographic āmainlandsā remained, which were not in the geographic range center. We used this model system to illustrate possible distributional shifts under stepped changes in biologically relevant aspects of climate, importance of land cover and taxonomic level in species-distribution forecasts, and impact of using a single threshold vs multiple categories of persistence probability in predicted range maps; we encourage additional research to further investigate the generality of these patterns.
Source: In: Narog, Marcia G., tech. coord. Proceedings of the 2002 Fire Conference: Managing fire... more Source: In: Narog, Marcia G., tech. coord. Proceedings of the 2002 Fire Conference: Managing fire and fuels in the remaining wildlands and open spaces of the Southwestern United States. Gen. Tech. Rep. PSW-GTR-189. Albany, CA: US Department of Agriculture, ...
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Papers by Mark C. Andersen