Treesearch

Historical fire regimes in the central United States maintained open-canopy shortleaf pine-oak woodlands on xeric sites. Following large-scale harvest and fire suppression, those woodlands grew denser with more continuous canopy cover, and they gained mesic species at the expense of shortleaf pine. There is high interest in restoring shortleaf pine-oak woodlands; most have been converted to other forest types but those that remain are valued for high stand-scale and landscape-scale diversity. Prior stand-scale studies suggest that prescribed burning and harvesting could be effective for...

The response of tropical forests to global warming is one of the largest uncertainties in predicting the future carbon balance of Earth. To determine the likely effects of elevated temperatures on tropical forest understory plants and soils, as well as other ecosystems, an infrared (IR) heater system was developed to provide in situ warming for the Tropical Responses to Altered Climate Experiment (TRACE) in the Luquillo Experimental Forest in Puerto Rico. Three replicate heated 4-m-diameter plots were warmed to maintain a 4°C increase in understory vegetation compared to three unheated...

Tropical forests play a critical role in carbon and water cycles at a global scale. Rapid climate change is anticipated in tropical regions over the coming decades and, under a warmer and drier climate, tropical forests are likely to be net sources of carbon rather than sinks. However, our understanding of tropical forest response and feedback to climate change is very limited. Efforts to model climate change impacts on carbon fluxes in tropical forests have not reached a consensus. Here, we use the Ecosystem Demography model (ED2) to predict carbon fluxes of a Puerto Rican tropical forest...

Hobbseus yalobushensis, the Yalobusha rivulet crayfish, is a species of conservation concern because it is known from only six localities in parts of three central Mississippi counties. No studies have focused on the species since its description in 1989. Our objectives were to: (1) identify additional H. yalobushensis localities within a landscape managed intensively for loblolly pine (Pinus taeda) production, (2) relate stream size, water quality variables, and flow permanence to species presence or density, (3) characterize the aquatic community in relation to H. yalobushensis, (4)...

Most uses of remotely sensed satellite data to characterize wildlife habitat have used metrics such as mean NDVI (Normalized Difference Vegetation Index) in a year or season. These simple metrics do not take advantage of the temporal patterns in NDVI within and across years and the spatial arrangement of cells with various temporal NDVI signatures. Here we use 13 years of data from MODIS (Moderate Resolution Imaging Spectroradiometer) to bin individual MODIS pixels (5.3 ha) into phenoclasses, where each phenoclass consists of pixels with a particular temporal profile of NDVI, regardless of...

As a result of widespread mortality from beetle infestation in the forests of the western United States, there are substantial stocks of biomass suitable as a feedstock for energy production. This study explored the financial viability of four production pathway scenarios for the conversion of beetle-killed pine to bioenergy and bioproducts in the Rocky Mountains. Monte Carlo simulation using data obtained from planned and existing projects was used to account for uncertainty in key technoeconomic variables and to provide distributions of project net present value (NPV), as well as for...

Using the results of a choice modeling survey, internet, mail-only and mixed internet and mail survey modes were examined with regards to their cost-effectiveness, representativeness, and willingness to pay (WTP). The topical focus of the study was biomass energy generation preferences of the residents of Montana, Colorado and Arizona, USA. Compared to the mail and mixed mode samples, the internet-only mode produced a sample of respondents that was younger, more likely to have a college degree, and more likely to have a household income of at least $100,000 per year. However, observed...

The National Water Model is a dynamic and fast-moving initiative with a wide variety of contributors intended to serve an even wider audience, from fellow scientists to emergency managers to water recreation. For perspective on the depth and breadth of the model and its potential impact, a variety of groups from federal to local government, watershed authorities and industry were asked to share their involvement and thoughts on future use of the National Water Model forecasts.

Stable isotope compositions of mercury (Hg) were measured in the outlet stream and in soil cores at different landscape positions in a 9.7-ha boreal upland-peatland catchment. An acidic permanganate/persulfate digestion procedure was validated for water samples with high dissolved organic matter (DOM) concentrations through Hg spike addition analysis. We report a relatively large variation in mass-dependent fractionation (δ202Hg; from −2.12 to −1.32‰) and a smaller, but significant, variation of mass-independent fractionation (Δ199Hg; from −0.35 to −0.12‰) during two years of sampling with...

Increases in area burned and fire size have been reported across a wide range of forest and shrubland types in the Western United States in recent decades, but little is known about potential changes in fire regimes of piñon and juniper land cover types. We evaluated spatio-temporal patterns of fire in piñon and juniper land cover types from the National Gap Analysis Program using Monitoring Trends in Burn Severity (MTBS 2016) data (1984 through 2013) for Northern and Southern Intermountain and Central and Southern Rocky Mountain geographic regions. We examined differences in total area...