Estimation Using Contingent Valuation Data from a "Dichotomous Choice with Follow-Up" Questionnaire

Dichotomous-choice (referendum) contingent-valuation questions are inefficient in that a very large number of observations is required to identify a distribution of resource values with any degree of accuracy. An alternative questioning strategy introduces a follow-up dichotomous-choice question. We generalize upon previous analyses of this type of data by relaxing the assumption that the identical unobserved resource value motivates both responses. While values implied by the first and second responses are highly correlated and may be drawn from the same distribution, they are definitely not identical. Furthermore, assuming that they are can severely distort the estimated valuation distribution.     

Resource problems in the eighties: An essay

Summary This article presents a brief overview of the more severe problems which must be addressed by natural resource planners and managers in the eighties.Professor Fred Curtis is senior author of this paper which, although written in a style which offers light reading, serves as a reminder from Canada that the resource problems of the '70s are ever present today in the '80s. The address given is that of Prof. Curtis. Paul Simpson-Housley is a member of staff in the Department of Geography, York University, 4700 Keele Street, Downsview, Ontario M3J 1P3 and Messrs Kent and Blakely maybe contacted through the senior author.     

Female preferences for male calling bout duration in a field cricket

Summary The calls of male field crickets attract sexually receptive females. In Gryllus integer, males differ from one another in their durations of uninterrupted calling (calling bout lengths). Tape recordings of the calls of 50 wild-caught males revealed that 14 males spent most of their calling time in short bouts (Fig. 1A), 18 in both short and long bouts (Fig. 1B), and 18 in long bouts (Fig. 1C). Re-recordings of 32 males after 3 weeks showed that calling bout lengths of individual males are stable with time (age) (Fig. 2). Three phonotaxis experiments investigated whether calling bout lengths of males affect female preferences. They demonstrated that (1) females can discriminate among conspecific males on the basis of calls alone; (2) females are preferentially attracted to males with long calling bout lengths; and (3) calling bout length is the specific factor responsible for preferential attraction. These results precisely identify a criterion that females use to discriminate among potential mates of their own species.     

Remote sensing for land management and planning

The primary role of remote sensing in land management and planning has been to provide information concerning the physical characteristics of the land which influence the management of individual land parcels or the allocation of lands to various uses These physical characteristics have typically been assessed through aerial photography, which is used to develop resource maps and to monitor changing environmental conditions These uses are well developed and currently well integrated into the planning infrastructure at local, state, and federal levels in the United States.Many newly emerging uses of remote sensing involve digital images which are collected, stored, and processed automatically by electromechanical scanning devices and electronic computers Some scanning devices operate from aircraft or spacecraft to scan ground scenes directly; others scan conventional aerial transparencies to yield digital images. Digital imagery offers the potential for computer-based automated map production, a process that can significantly increase the amount and timeliness of information available to land managers and planners.Future uses of remote sensing in land planning and management will involve geographic information systems, which store resource information in a geocoded format. Geographic information systems allow the automated integration of disparate types of resource data through various types of spatial models so that with accompanying sample ground data, information in the form of thematic maps and/ or aerially aggregated statistics can be produced Key issues confronting the development and integration of geographic information systems into planning pathways are restoration and rectification of digital images, automated techniques for combining both quantitative and qualitative types of data in information-extracting procedures, and the compatibility of alternative data storage modes     

Demand and supply considerations for evaluating a new distance education program in natural resources planning and management in North America

Summary This paper describes the demand and supply information requirements to determine whether a curriculum for a new program, Natural Resources Planning and Management (NRPM), should be developed by Athabasca University (AU). Demand considerations assist in determining forecasted job opportunities and student needs. Supply considerations, including the type and location of existing natural resource programs and their student enrollment levels, assist in determining the enrollment level, the type of degree program, and that the student profile of AU's NRPM graduates will be high, particularly in western Canada. AU has, therefore, been advised to offer an undergraduate bachelor's degree in NRPM. This paper also serves as a model, for organizing demand and supply information for any new university or college program.Fred Curtis, is Professor and Co-ordinator of Regional Systems Engineering, at the University of Regina, Regina, Saskatchewan, Canada. His teaching and research areas include environmental and behavioural systems engineering. His recent publications focus on environmental impact assessment procedures, environmental mediation, natural resources planning and management, energy conservation and land use planning and distance education.     

THE CENTRAL ARIZONA WATER CONTROL STUDY: A CASE FOR MULTIOBJECTIVE PLANNING AND PUBLIC INVOLVEMENT1

This paper describes the successful application of a multiobjective planning framework, incorporating substantial public involvement, to a major water resources decision involving intense confilcts. The study was initiated to help resolve more than a decade of controversy over a project proposed to control flooding and provide regulatory storage in the Phoenix, Arizona, area. The public was actively involved in the development of study goals and the specification of acceptable tradeoffs between multiple objectives. A wide range of structural and nonstructural alternatives was formulated and evaluated in relation to these objectives, and broad-based support was developed for a new plan. Reasons for the successful outcome are discussed, as well as implications for water resources planning under the new Federal Principles and Guidelines.     

Semi-Direct Lysis of Swabs and Evaluation of Their Efficiencies to Recover Human Noroviruses GI and GII from Surfaces

Enteric viruses such as noroviruses (NoVs) continue to be the cause of widespread viral outbreaks due to person-to-person transmission, contaminated food, and contaminated surfaces. In order to optimize swabbing methodology for the detection of viruses on (food) contact surfaces, three swab elution/extraction strategies were compared in part one of this study, out of which, one strategy was based on the recently launched ISO protocol (ISO/TS 15216-1) for the determination of hepatitis A virus and NoV in food using real-time RT-PCR (RT-qPCR). These three swab elution/extraction strategies were tested for the detection of GI.4 and GII.4 NoV on high-density polyethylene (HD-PE) surfaces with the use of cotton swabs. For detection of GI.4 and GII.4, the sample recovery efficiency (SRE) obtained with the direct lysis strategy (based on ISO/TS 15216-1) was significantly lower than the SRE obtained with both other strategies. The semi-direct lysis strategy was chosen to assess the SRE of two common swabs (cotton swab and polyester swab) versus the biowipe (Biomérieux, Lyon, France) on three surfaces (HD-PE, neoprene rubber (NR), and nitrile gloves (GL)). For both surfaces, HD-PE and GL, no significant differences in SREs of GI.4 and GII.4 NoVs were detected between the three different swabs. For the coarser NR, biowipes turned out to be the best option for detecting both GI.4 and GII.4 NoV.     

Ability of chestnut oak to tolerate acorn pruning by rodents

Acorns of many white oak species germinate soon after autumn seed fall, a characteristic widely interpreted as a general adaptation to escape predation by small rodents. However, the mechanism by which early, rapid germination allows escape and/or tolerance of seed damage remains unclear. Here we reported how specific germination traits of chestnut oak (Quercus montana) acorns, and those of other white oak species, allow successful escape from acorn pruning by rodents. During germination, chestnut oak acorns develop elongated cotyledonary petioles, which extend beyond the distal end of the acorn (1–2 cm) to the point at which the epicotyl and radicle diverge. However, granivorous rodents often prune the taproots above or below the plumule when eating or caching these germinated acorns in autumn. Hence, we hypothesized elongation of cotyledonary petioles allows chestnut oaks to escape acorn pruning by rodents. We simulated pruning by rodents by cutting the taproot at different stages of germination (radicle length) to evaluate the regeneration capacity of four resulting seedling remnants following taproot pruning: acorns with the plumule (remnant I), acorns without the plumule (remnant II), and pruned taproots with (remnant III) or without the plumule (remnant IV). Our results showed that remnant I germinated into seedlings regardless of the length of the taproot previously pruned and removed. Remnant III successfully germinated and survived provided that taproots were ≥6 cm in length, whereas remnant IV was unable to produce seedlings. Remnant II only developed adventitious roots near the severed ends of the cotyledonary petioles. Field experiments also showed that pruned taproots with the plumule successfully regenerated into seedlings. We suggest that the elongated cotyledonary petioles, typical of most white oak species in North America, represent a key adaptation that allows frequent escape from rodent damage and predation. The ability of pruned taproots to produce seedlings suggests a far greater resilience of white oaks to seed predation than previously anticipated.