John Hof

Accounting for connectivity and spatial correlation in the optimal placement of wildlife habitat

This paper investigates optimization approaches to simultaneously modelling habitat fragmentation and spatial correlation between patch populations. The problem is formulated with habitat connectivity affecting population means and variances, with spatial correlations accounted for in covariance calculations. Population with a pre-specifled confidence level is then maximized in nonlinear programs that define habitat patches as circles (fixed shape) or rectangles (variable shape). The ideas and model formulations are demonstrated in a case example with a maximum of four habitat patches. Spatial layout of habitat is strongly sensitive to species dispersal characteristics and the spatial correlation structure resulting from different environmental disturbance agents.

OPTIMIZATION OF HABITAT PLACEMENT: A CASE STUDY OF THE NORTHERN SPOTTED OWL IN THE OLYMPIC PENINSULA

The purpose of this paper is to develop an optimization procedure that can be used with simulation methods to capture the strengths of both in analyzing habitat layouts. We present a static optimization model for spatially locating habitat, using the Northern Spotted Owl in the Olympic Peninsula, Washington State (USA) as a case study. Optimization model parameters, including adult survival, fecundity, and occupancy of sites, are generated with an extant simulation model, and both models are used together to evaluate an alternative plan for the recovery of this high-visibility species. This plan is generally supported by the analysis, but some gains are indicated to be possible from trading off some federally managed habitat for nonfederal habitat (though such a trade-off may not be realistically practical).

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.

Long-term outdoor recreation participation projections for public land management agencies.

ABSTRACTThis paper presents a theoretical structure for developing long-term outdoor recreation projections for public agencies. The suggested approach is demonstrated using data from the 1977 Nati...

On the necessity of simultaneous recreation demand equation estimation.

This paper provides an empirical framework for testing a welfare change measure by considering the following problem: a public agency is faced with the decision of how to maximize public welfare from optimally locating a large-scale national recreational ...

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.

An analysis of joint costs in a managed forest ecosystem

Abstract This paper analyzes the tenability of line item budgeting and independently determined output costs for a managed forest ecosystem. The general problem of cost allocation in a joint production system is discussed as one of choosing paths of integration. A production structure is hypothesized for describing a managed forest ecosystem and its characteristics of “jointness” are discussed. Finally, an empirical case example is presented which indicates that cost estimates and associated means of production which result from single output costing procedures and from joint costing procedures may be significantly different in a managed forest ecosystem.

A Multilevel Analysis of Production Capabilities of the National Forest System

This paper reports an analysis of multiresource production capabilities of the National Forest System for the purpose of national planning in the USDA Forest Service. The analysis identifies previously unrecognized limits to the productive capabilities of the National Forest System. The analysis was used by Forest Service planners to define the long-run planning problem and to develop alternative strategies for addressing that problem. We test a multilevel optimization approach and apply it to all forest system regions of the coterminous United States. We conclude that it is not feasible for the National Forest System to supply a constant proportion of all projected resource needs. Furthermore, we found that even more conservative levels of outputs require significant increases in investment and management intensity. These results have led to Forest Service program alternatives involving more reliance on other forest and rangelands and more intense multiresource management of the National Forest System. Finally, these conclusions are limited by the range of alternatives generated and outputs modeled in the National Forest planning effort.

Carbon fixation in trees as a micro optimization process: an example of combining ecology and economics

This paper demonstrates how optimization procedures commonly used in microeconomics can be directly applied in studying ecological systems. Two alternative economic-analog models of carbon fixation in trees are developed that yield mutually exclusive, testable hypotheses regarding plant functioning. The first is a relatively straight-forward economic analog where carbon serves as the currency and the plant is modeled as a maximizer of net carbon gain (a profit analog). The second models carbon ‘revenue’ as the minimum of two functions that relate carbon gain to leaf and root biomass, respectively. The plant is then modeled with a MAXMIN operator, such that the minimum net revenue is maximized. Both models imply that leaves and roots are simultaneously limiting factors, but the second (MAXMIN) model implies that they are not ‘equally’ limiting. A parameterized version of the hiAXMIN model is developed, and sensitivity analysis performed to demonstrate how the model behaves biologically.