Treesearch

Dynamic hydrochemical models are useful tools for understanding and predicting the interactive effects of climate change, atmospheric CO2, and atmospheric deposition on the hydrology and water quality of forested watersheds. We used the biogeochemical model, PnET-BGC, to evaluate the effects of potential future changes in temperature, precipitation, solar radiation, and atmospheric CO2 on pools, concentrations, and fluxes of major elements at the Hubbard Brook Experimental Forest in New Hampshire, United States. Future climate projections used to run PnET-BGC were generated specifically...

Anthropogenic climatic change can no longer be considered an abstract possibility. It is here, its effects are already evident, and changes are expected to accelerate in coming decades, profoundly altering wilderness ecosystems. At the most fundamental level, wilderness stewards will increasingly be confronted with a trade-off between untrammeled wilderness character and primeval, natural conditions, accompanied by increasing impetus for management intervention. Possible strategic responses to climatic change fall into four broad classes: restraint (do nothing), resilience, resistance...

As previously indicated, GEO-5 shifts the GEO focus from identifying environmental problems to identifying solutions that governments can then prioritize. This chapter provides examples of a number of policy options and market mechanisms that have shown some success in improving environmental conditions in North America. They are organized by priority environmental theme and their success is related to how they may have helped to speed up the attainment of selected international environmental goals.

This paper presents a selected set of existing and new metrics for gauging Bayesian network model performance and uncertainty. Selected existing and new metrics are discussed for conducting model sensitivity analysis (variance reduction, entropy reduction, case file simulation); evaluating scenarios (influence analysis); depicting model complexity (numbers of model variables, links, node states, conditional probabilities, and node cliques); assessing prediction performance (confusion tables, covariate and conditional probability-weighted confusion error rates, area under receiver operating...

Hydraulic redistribution is the process of passive water movement from deeper moist soil to shallower dry soil layers using plant roots as conduits. Results from this study indicate that this phenomenon exists among two shrub species (Guiera senegalensis and Piliostigma reticulatum) that co-exist with annual food crops in Sahelian agro-ecosystems. Real-time measurements were conducted for soil water content, soil water potential and microclimate variables notably; air temperature, relative humidity, wind speed, precipitation and solar irradiance. Additionally, sap flow measurements were...

Loss of genetic variation through genetic drift can reduce population viability. However, relatively little is known about loss of variation caused by the combination of fluctuating population size and variance in reproductive success in age structured populations. We built an individual-based computer simulation model to examine how actual culling and hunting strategies influence the effective population size (Ne) and allelic diversity in Yellowstone bison over 200 years ( 28 generations). The Ne for simulated populations ranged from 746 in stable populations of size 2000 up to 1165 in...

Conservation biology research exhibits a striking but unhelpful dichotomy. Analyses of species decline, extinction risk, and threat mitigation typically encompass broad taxonomic and spatial scales. By contrast, most studies of recovery lack generality, pertaining to specific species, populations, or locales. Narrowly focused analyses offer a weak empirical basis for identifying generic recovery correlates across species, particularly in cases where recovery is not effected by an abatement of threats. We present a research framework for multi-species metaanalyses to identify early-warning...

The common earthworm Lumbricus terrestris L. is an invasive species that was introduced to North America by European settlers. Subsequently, earthworms have been distributed by human activity, invaded a wide geographic range and changed previously earthwormfree ecosystems. In the present study we analyzed seven European and four North American populations from a wide geographic range at three formerly described nuclear microsatellite markers. All three markers produced multi-banding patterns and marker presence versus absence was scored in 88 narrow size intervals. Similar levels of...

Understanding fine-grain patterns of forest disturbance and regrowth at the landscape scale is critical for effective management, particularly in forests in western Washington, Oregon, and California, U.S., where the policy known as the Northwest Forest Plan (NWFP) was imposed in 1994 over > 8 million ha of forest in an effort to balance environmental and economic tensions. We developed approaches to create disturbance and regrowth maps for forests within the area of the NWFP from the results of LandTrendr, a temporal segmentation algorithm described previously only at the pixel scale....

We used an in situ steady state 15N-labeled nitrate and acetate well-to-wells injection experiment to determine how the availability of labile dissolved organic carbon as acetate influences microbial denitrification in the hyporheic zone of an upland (third-order) agricultural stream.