Aquatic leeches (Hirudinea) as bioindicators of organic chemical contaminants in freshwater ecosystems

Freshwater leeches from an industrially polluted creek were found to contain very high residues of chlorophenols, when compared with fish, tadpoles and most other benthic invertebrates. Leeches are recommended as possible bioindicators of aquatic organic contamination.     

The problem of scale in community resource management

Scale is a fundamental variable in most community resource management programs. This is true both in terms of scale as a management concept (i.e., local, regional, and national level management) as well as a mapping concept (i.e., units on the map per unit on the ground). Julian Steward, the father of human ecology, recognized as early as 1950 that social scientists have failed to develop methods for incorporating the effect of scale in their work. This article seeks to determine whether methods used in plant and animal ecology for assessing the effects of scale are applicable to community resource management. The article reviews hierarchy theory and multiple scales, two methods (one theoretical and the other practical) for dealing with problems that span many scales. The application of these methods to community resource management programs is examined by way of an example.     

Opportunity costs of implementing forest plans

Intellectual concern with the National Forest Management Act of 1976 has followed a course emphasizing the planning aspects of the legislation associated with the development of forest plans. Once approved, however, forest plans must be implemented. Due to the complex nature of the ecological systems of interest, and the multiple and often conflicting desires of user clientele groups, the feasibility and costs of implementing forest plans require immediate investigation. For one timber sale on the Coconino National Forest in Arizona, forest plan constraints were applied and resulting resource outputs predicted using the terrestrial ecosystem analysis and modeling system (TEAMS), a computer-based decision support system developed at the School of Forestry, Northern Arizona University, With forest plan constraints for wildlife habitat, visual diversity, riparian area protection, and soil and slope harvesting restrictions, the maximum timber harvest obtainable was reduced 58% from the maximum obtainable without plan constraints.Former Graduate Student at Northern Arizona University.     

Correlates of relocation intention and emotional responses to an Israeli plant relocation

Prior to a relocation of a governmental organization in Israel, 155 workers responded to a questionnaire tapping three criteria: the intention to relocate, positive feelings, and stress reactions. The questionnaire also addressed potential correlates: biographical data, family-related variables, perceived attitudes of co-workers, job satisfaction and centrality, and anticipations regarding work and nonwork aspects. The intention to relocate was associated mainly with the perceived attitude of the spouse and the children. Stress experienced was most strongly related to the future job prospects, and the positive emotions were mostly correlated with the perceived favourability of the anticipated changes. The family-related variables were found to be significantly correlated with all the criteria. These results suggest that organization should direct efforts on spouse and children in order to influence employees' decisions and feelings regarding relocation. This and other implications are discussed.     

Which regional features of Danish agriculture favour the corn bunting in the contemporary farming landscape?

Corn buntings Miliaria calandra were abundant throughout arable agricultural landscapes in Europe, but have catastrophically declined since the mid 1970s with changes in farming practice and now give serious conservation cause for concern. Corn buntings declined in Denmark during 1976–1993, but (almost unique in Europe) have since increased (by up to 11% per annum) in some areas without specific conservation recovery actions. Based on breeding bird surveys in the mid 1990s, highest corn bunting densities occurred on mixed agriculture in west Denmark (Jylland); the species was rarer or absent in regions of highest arable land cover. Corn bunting density and extent of rotational and permanent grassland were correlated, but not with spring sown barley (all known to constitute important corn bunting winter habitat). The extent of spring barley rapidly declined in Denmark during the 1980s, but since 1990, most counties have since shown 2–3% annual increases in this crop, except in Nordjylland, where high densities of corn buntings have remained stable. Elsewhere in Jylland, corn buntings have increased in counties supporting highest densities during the mid 1990s, contrasting stable or declining trends in south and east Denmark where densities were originally lower. After dramatic decreases everywhere in Denmark, corn buntings retain highest breeding densities associated with mixed agriculture, especially where grassland and spring sown barley remained in greatest extent. Although purely based on land use correlation and bird surveillance, these results show an association between mixed farming and favourable conservation status of a species now red-listed throughout much of Europe. Further investigations of habitat use at small spatial scales and throughout the annual cycle are urgently required to better enlighten specific recommendations for wider applicability of guidelines for corn bunting recovery actions elsewhere.     

A coupled carbon-water-energy-vegetation model to assess responses of temperate forest ecosystems to changes in climate and atmospheric CO2. Part I. Model concept

Predictions of forest ecosystem response to changes in climate and atmospheric CO(2) concentration require hierarchically structured process models. Present forest simulation models have conceptual limitations that restrict their application to climate-change studies. A major drawback of forest succession models is that they often lack physiological details in the simulation of annual tree growth. On the other hand, aggregated ecosystem models assume spatially homogeneous forests, and do not account for successional changes in forest composition and canopy structure. The concept of a new coupled carbon-water-energy-forest vegetation model is presented which attempts to overcome the main limitations of existing models by implementing a modern view of ecological hierarchy and a robust approach for scaling ecological processes in space and time.