Michael Bevers

Spatial optimization of prairie dog colonies for black-footed ferret recovery

A discrete-time reaction-diffusion model for black-footed ferret release, population growth, and dispersal is combined with ferret carrying capacity constraints based on prairie dog population management decisions to form a spatial optimization model. Spatial arrangement of active prairie dog colonies within a ferret reintroduction area is optimized over time for maximum expected adult ferret population. This modeling approach is applied in an exploratory case study to a black-footed ferret reintroduction program in Badlands National Park and Buffalo Gap National Grassland, South Dakota. The model is currently being used to evaluate prairie dog population management alternatives and captive-bred ferret release locations for the Buffalo Gap National Grassland. This approach is also being adapted for use on other grasslands and with other species in the northern Great Plains.

Spatial and temporal optimization in habitat placement for a threatened plant: the case of the western prairie fringed orchid

This paper investigates an optimization approach to determining the placement and timing of habitat protection for the western prairie fringed orchid. This plant’s population dynamics are complex, creating a challenging optimization problem. The sensitivity of the orchid to random climate conditions is handled probabilistically. The plant’s seed, protocorm and above-ground stages are all accounted for in a case example from the Sheyenne National Grassland in North Dakota. Sensitivity of the case example model to dispersal assumptions and climate condition probabilities is demonstrated.

Optimizing habitat location for black-tailed prairie dogs in southwestern South Dakota

A spatial optimization model was formulated and used to maximize black-tailed prairie dog populations in the Badlands National Park and the Buffalo Gap National Grassland in South Dakota. The choice variables involved the strategic placement of limited additional protected habitat. Population dynamics were captured in formulations that reflected exponential population growth combined with the recalcitrant dispersal behavior of this social mammal that is important to many other species. The model results are compared to a previous paper which modeled the black-footed ferret, an aggressive disperser that is dependent upon prairie dogs for food and shelter.

Economics of a nest-box program for the conservation of an endangered species: a reappraisal

An optimization model is developed to identify timing and placement strategies for the installation of nest boxes and the harvesting of timber to meet joint timber–wildlife objectives. Optimal management regimes are determined on the basis of their impacts on the local abundance of a threatened species and net present value (NPV) and are identified for a range of NPV levels to identify production possibility frontiers for abundance and NPV. We apply the model to a case study focusing on an area of commercially productive mountain ash (Eucalyptus regnans F. Muell.) forest in the Central Highlands region of Victoria, Australia. The species to be conserved is Leadbeater’s possum (Gymnobelideus leadbeateri McCoy), which is locally limited by a scarcity of nesting hollows. The modeling is exploratory but indicates that nest boxes may offer a promising population recovery tool if consideration is taken of their placement and areal extent through time. Résumé : Les auteurs ont développé un modèle d’optimisation pour identifier les stratégies concernant le moment et l’emplacement pour l’installation de nichoirs et la récolte de bois afin de rencontrer les objectifs conjoints pour la matière ligneuse et la faune. Les régimes optimaux d’aménagement sont déterminés sur la base de leurs impacts sur l’abondance locale d’une espèce menacée et la valeur nette actualisée. Ils sont identifiés pour une gamme de niveaux de valeur nette actualisée afin d’identifier les limites possibles de production en fonction de l’abondance et de la valeur nette actualisée. Nous appliquons le modèle à une étude de cas concentrée dans une zone de forêt commerciale productive d’eucalyptus géant (Eucalyptus regnans F. Muell.) sur le plateau central dans la région de Victoria en Australie. L’espèce à conserver est le bucorve du Sud (Gymnobelideus leadbeateri McCoy) qui est localement en nombre limité à cause de la rareté des cavités pouvant servir de nichoir. La modélisation est exploratoire mais indique que les nichoirs peuvent constituer un outil intéressant pour rétablir la population si leur emplacement et leur répartition dans le temps sont pris en considération. [Traduit par la Rédaction] Spring et al. 2003

Prescribing Habitat Layouts: Analysis of Optimal Placement for Landscape Planning

Physical restructuring of landscapes by humans is a prominent stress on ecological systems (Rapport et al. 1985). Landscape restructuring occurs primarily through land-use conversions or alteration of native habitats through natural resource management. A common faunal response to such land-use intensification is an increased dominance of opportunistic species leading to an overall erosion of biological diversity (Urban et al. 1987). Slowing the loss of biodiversity in managed systems will require interdisciplinary planning efforts that meld analysis approaches from several fields, including landscape ecology, conservation biology, and management science.

Sustaining Wildlife Populations in Productively Managed Forests

Wildlife population status is becoming a key consideration in determining whether wood fiber production from managed forests can be sustained. Concerns for wildlife have become a very important part of public land management in many areas of the world and are being given increased weight on privately owned lands. Jointly maintaining wood fiber production and wildlife populations requires an ability to spatially and temporally design management activities so as to mitigate negative impacts on wildlife habitat. Consequently, research efforts that blend wildlife population persistence modeling with traditional forest management modeling can potentially play a crucial role in maintaining future forest productivity. In this chapter, we synthesize recent and ongoing research combining population reaction-diffusion models with spatial forest management optimization methods for planning the location, timing, and intensity of harvests to simultaneously sustain wildlife and wood fiber production.