Treesearch

Pore-scale dispersion (PSD), aquifer heterogeneity, sampling volume, and source size influence solute concentrations of conservative tracers transported in heterogeneous porous formations. In this work, we developed a new set of analytical solutions for the concentration ensemble mean, variance, and coefficient of variation (CV), which consider the effects of all these factors. We developed these models as generalizations of the first-order solutions in the log-conductivity variance of point concentration proposed by [Fiori A, Dagan G. Concentration fluctuations in aquifer transport: a...

Pinyon-juniper (Pinus edulis - Juniperus spp.) woodlands in the American Southwest have expanded in many areas since the late Nineteenth century. Woodland expansion has occurred in both, extent and increasing stand density. Expansion of woodlands has been attributed to reduced fire frequency, increased ungulate grazing, and changes in climate. These increases of woody vegetation have been shown to alter nutrient cycling, fire dynamics, and vegetation patterns across the landscape which can have large-scaled impacts on ecosystem function. Recently, pinyon-juniper woodlands and the American...

We investigated poult survival from hatching to 4 wks of age for Merriam's wild turkey (Meleagris gallopavo merriami) poults in the southern Black Hills, South Dakota. We estimated survival from 841 poults reared by 57 radio-marked wild turkeys (n = 52 adult females, n = 5 yearling females). Survival of poults to 4 wks posthatch averaged 33 percent with 54 percent of the mortality occurring in the first 7 days after hatching. Merriam's turkey poult survival in the southern Black Hills was low compared to Merriam's populations found elsewhere in the entire current range. Survival of poults...

Sexual reproductive success in wild plant populations is dependent upon the ability to bank seed for when environmental conditions favor seedling recruitment. Seed production in many plant populations requires the pollination services of local bee populations. A loss in bee diversity as a result of exotic plant invasion or revegetation practices which do not adequately restore the flowering plant resources that support pollinators, contributes to habitat fragmentation. Even after successful pollination, developing ovules and maturing seed are subject to predation by insects. Several...

The primary impetus for this Wildfire Forum is a document authored by John McLain and Sheila Anderson of Resource Concepts, Inc. entitled "Urgent Need for a Scientific Review of the Ecological and Management History of the Great Basin Natural Resources and Recommendations to Achieve Ecosystem Restoration." This document urged prominent scientists who have spent their careers studying, observing and working to manage the Great Basin ecosystem to pool their collective knowledge and experience over the last four decades, summarize their studies and provide recommendations to address the...

Estimating nest success and identifying important factors related to nest-survival rates is an essential goal for many wildlife researchers interested in understanding avian population dynamics. Advances in statistical methods have led to a number of estimation methods and approaches to modeling this problem. Recently developed models allow researchers to include a covariate that varies by individual and time. These techniques improve the realism of the models, but they suffer from a lack of available diagnostic tools to assess their adequacy. The PROC NLMIXED procedure in SAS offers a...

Native salmonid fishes often face simultaneous threats from habitat fragmentation and invasion by nonnative trout species. Unfortunately, management actions to address one may create or exacerbate the other. A consistent decision process would include a systematic analysis of when and where intentional use or removal of barriers is the most appropriate action. We developed a Bayesian belief network as a tool for such analyses. We focused on native westslope cutthroat trout (Oncorhynchus clarkii lewisi) and nonnative brook trout (Salvelinus fontinalis) and considered the environmental...

Restoration/fuel reduction treatments are being widely used in fire-prone forests to modify stand structure, reduce risks of severe wildfire, and increase ecosystem resilience to natural disturbances. These treatments are designed to manipulate stand structure and fuels, but may also affect understory vegetation and biodiversity. In this study, we describe prescribed fire and thinning treatment effects on understory vegetation species richness, cover, and species composition in dry coniferous forests of central Washington State, U.S.A. We applied thinning and prescribed fire treatments in...

Methods for evaluating the impact of fires within tropical forests are needed as fires become more frequent and human populations and demands on forests increase. Short- and long-term fire effects on soils are determined by the prefire, fire, and postfire environments. We placed these components within a fire-disturbance continuum to guide our literature synthesis and develop an integrated soil burn severity index. The soil burn severity index provides a set of indicators that reflect the range of conditions present after a fire. The index consists of seven levels, an unburned level and...

We synthesized post-fire road treatment information to assist BAER specialists in making road rehabilitation decisions. We developed a questionnaire; conducted 30 interviews of BAER team engineers and hydrologists; acquired and analyzed gray literature and other relevant publications; and reviewed road rehabilitation procedures and analysis tools. Post-fire road treatments are implemented if the values at risk warrant the treatment and based on regional characteristics, including the timing of first damaging storm and window of implementation. Post-fire peak flow estimation is important...