Traditional travel cost analysis has either ignored multiple destination trips or arbitrarily allocated trip costs across visited sites. In this paper, combinations of multiple destinations are treated as unique sites and incorporated into a demand system. Empirical demand functions for multiple destination trips that include Bryce National Park are estimated. Consumer surplus calculations for single destination and multiple destination trips are compared.
Wildlife species viability optimization models are developed to convert a given set of initial forest conditions, through a combination of natural growth and management treatments, to a forest system which addresses the joint habitat needs of multispecies populations over time. A linear model of forest cover and wildlife populations is used to form a system of forest management control variables for wildlife habitat modification. The paper examines two objective functions coupled to this system for optimizing sustainable joint species viability. The first maximizes the product of periodic joint viabilities over all time periods, focusing management resources on long‐term equilibria, with less emphasis on conversion strategy. The second iteratively maximizes the minimum periodic joint viability over all time periods. This focuses management resources on the most limiting time periods, typically the conversion phase periods. Both objective functions resulted in either point or cyclic equilibria, with cycle lengths equal to minimum forest treatment ages. A third objective, based on maximizing the minimum individual species periodic viability is used to examine single species emphasis. Examples are developed through a case study of 92 vertebrate species found in coastal Douglas‐fir stands of northwestern California.
We investigated three approaches for finding optimum allocations of forest age-classes to meet multispecies conservation objectives for a community of terrestrial vertebrate species. We illustrate our approaches using data on relative abundances of 92 species of amphibians, reptiles, birds, and mammals sampled from five habitat types (age-classes) of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) forests in northwestern California. Our three approaches involved maximizing (i) the expected number of viable species; (ii) the minimum probability of viability among all species; and (iii) the joint probability of viability across all species. Each approach was demonstrated using an assumption that viability is linearly related to abundance or that viability is logistically related to abundance. We discuss limitations of our approach focusing on assumptions of data quality, relative conservation priority among taxa, relationships between estimated abundance of a population and its probability of viability, interspecific interactions, and the need for evaluation of spatial distribution of habitats.
Net retumm to laveetment on weetern ranches are often low or negative. Ranchem who graze cattle on federal raoge during the summer in Colorado were eampled to determk the& wllllngnesa to wll their rmchee and to detemdne which factom were important ln their dedsloa to ranch. Cluster uulysia waa used to classify the rancher8 into 4 groups. Willingnena to rll the much wm the most important factor in clessitylng groupa. Approsbnately 75% of the federal pemdtteee would not coneider selling their ranches lo the current market wblle over half rupooded that rate of return oo lnvestmeot wea of llttle or oo importance IO their dectslon to be in the cattle bueineee. The groups also differed with respect to the lmportmce of being near fmlly and Idends, and labor end amet mobility. Key Wordaz publk la&, raocher behavior Net returns to capital and management in western range livestock operations are often low or negative. This fact has prompted some economists to view a ranch as a consumption good to some degree rather than a pure production enterprise (Smith and Martin 1972). Consumptive components such as the value of a rural lifestyle or a land ethic could raise ranch prices beyond that which economic returns from livestock would justify. The degree to which these consumption attributes dominate ranch decisions will vary with the values of individual ranchers. The purpose of this paper is to determine what motivates ranchers to stay in ranching. We grouped ranchers based on the importance they placed on various attributes including their willingness to sell their ranches. The results apply to ranchers using forage from federal land during the summer of 1983 in Colorado. The research reported here was part of a study that applied the contingent valuation method to estimate the demand for summer forage from federal land in Colorado (McKean et al. 1986). Therefore, Colorado ranchers not using federal forage were not included in the population. Social parameters were measured and related to demand for forage. Methods A mail survey was used to elicit attitudes from a sample of ranchers. The questionnaire included Smith and Martin's questions defining "land fundamentalism" as a starting point (Smith 1971). Smith defined land fundamentalism as "the attitude that a greater amount of satisfaction can be received from associating directly with the physical environment than with the 'man-made*." Discussion with Rogers' aided the design of the social parameter questions. We concluded that we should reduce the redundancy in the "Land or Rural" preference questions that Smith and Martin USDA Forat Service d Colorulo St&c University with fundii from Colomdo State University Agricultural Experiment Station (Projca CO-191). The usual dischimer applies. hdwwxipt acqted 24 April 1989. QJer& D. 1983. Personal communication. Formerly profeuor and department * Dept. of sociology, Colomdo state uniwmity.
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.
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