Quantifying nitrogen process rates in a constructed wetland using natural abundance stable isotope signatures and stable isotope amendment experiments

This study describes the spatial variability in nitrogen (N) transformation within a constructed wetland (CW) treating domestic effluent. Nitrogen cycling within the CW was driven by settlement and mineralization of particulate organic nitrogen and uptake of NO3-. The concentration of NO3- was found to decrease, as the delta15N-NO3- signature increased, as water flowed through the CW, allowing denitrification rates to be estimated on the basis of the degree of fractionation of delta15N-NO3-. Estimates of denitrification hinged on the determination of a net isotope effect (eta), which was influenced byprocesses that enrich or deplete 15NO3- (e.g., nitrification), as well as the rate constants associated with the different processes involved in denitrification (i.e., diffusion and enzyme activity). The influence of nitrification on eta was quantified; however, it remained unclear how eta varied due to variability in denitrification rate constants. A series of stable isotope amendment experiments was used to further constrain the value of eta and calculate rates of denitrification, and nitrification, within the wetland. The maximum calculated rate of denitrification was 956 +/- 187 micromol N m(-2) h(-1), and the maximum rate of nitrification was 182 +/- 28.9 micromol N m(-2) h(-1). Uptake of NO3- was quantitatively more important than denitrification throughoutthe wetland. Rates of N cycling varied spatially within thewetland, with denitrification dominating in the downstream deoxygenated region of the wetland. Studies that use fractionation of N to derive rate estimates must exercise caution when interpreting the net isotope effect. We suggest a sampling procedure for future natural abundance studies that may help improve the accuracy of N cycling rate estimates.     

Legitimation Struggles in National Park Spaces: The Banff Bow Valley Round Table

This paper presents an in-depth analysis of a multi-stakeholder process, the Banff Bow Valley Round Table (BBVRT) convened by a federally appointed task force in 1995 to provide public input and participation in the Banff Bow Valley Study (BBVS). The purpose of this initiative was to address environmental concerns and conflict over governance, development and growth in Banff National Park, Canada. A key finding from the analysis discussed in this paper is how various participants struggled for legitimation at the negotiation table, and how the discourses of science and instrumental reason served to empower certain interests and agendas in the process. While the discursive appropriation of ecological science enabled some interests to dominate and to legitimize their concerns, this strategy may have intangible and costly consequences for consensus-based processes and for society overall. Analysis of these discursive struggles demonstrates the challenge of bringing ecology and the general public to the same negotiating table in a meaningful way. It shows the conflicting roles and identities of environmental groups who aspire to re-present nature (as a stakeholder) at the negotiating table. Recommendations for multi-stakeholder processes in planning and governance of national parks are presented, along with social implications in the context of historic human-environment dualism and conflict.     

Responses of Some Terrestrial Invertebrates to Catchment Treatments Applied at Loch Fleet

The impact of liming and heather-burning on the beetle and spider faunas of open and afforested moorland was studied by use of pitfall traps. of the 168 species identified, the catch of only one species, the ground beetle Trechus obtusus Erichson, increased in a way that could be related to intervention treatments. No species obviously declined as a result of the intervention treatments.     

An estimate of regional and global O3 damage from precursor NOx and VOC emissions

The results of the ozone models of EMEP and Harwell are combined with the C-R (concentration- response) functions and economic valuation recommended by the ExternE Project of the European Commission. The paper is exploratory, to assemble the available information, establish likely priority impact categories, and make recommendations for future research. Impacts on health and agriculture are evaluated. Based on the EMEP results, aggregate regional (Europe-wide) estimates of ozone damage, allocated per ton of precursor emission, are derived. Calculations on the global scale, using results from the Harwell Global Ozone Model (and the same valuation per nL/L O₃) indicate that damages outside Europe are likely to also be significant although somewhat smaller. For the EMEP Model, the numbers per ton of precursor emission are approximately the same for NO_x and for VOC. For NO_x, a value around $1875 (uncertainty range 375 to 10 000) per Mg _{NO2 equi} was found; for VOC, approximately $1100 per Mg_VOC was found. There is much uncertainty, especially in the C-R functions, and current assessments of ozone damages are, at best, order of magnitude estimates. Even though the overlap between local, regional, and global models is not clear, the results suggest that ozone damage is dominated by regional impacts.     

Predicting the distribution of ground beetle species (Coleoptera, Carabidae) in Britain using land cover variables

Predictions of plant and animal species distributions are important for conservation and for the assessment of large-scale ecosystem change. Land cover data are becoming more widely available for use in land management and conservation. We use a logistic regression modelling approach to investigate the utility of these data for modelling. The relationship between the distribution of 137 British ground beetles species and land cover was investigated using data from 1,687 10 km national grid squares. Land cover data were simplified using ordination and the axes used as predictors in logistic regression with presence absence data for individual beetle species as response variables. Significant regression models were generated for all species with first and second axis scores. The amounts of variation explained by models were generally low, but predictions derived from models generally matched the known distributions of the species in Britain. Species with coastal preferences were poorly modelled and predicted to occur throughout lowland Britain whilst a number of species occurring in southern Britain were predicted to occur into Scotland. A validation exercise comparing model predictions with new data from a survey of 59 10 km(2) produced mixed results with the distribution of grassland species being better predicted than riverine species. Jack-knifing was used to assess the robustness of models for four species which differed in their apparent responses to the land cover variables. Methods for improving the predictive power of these models and their potential for use in assessing the impact of global climate change are discussed.