Treesearch

We analyzed the ecosystem effects of low-temperature events (<5 °C) over 4 years (2009-2012) in subtropical short and long hydroperiod freshwater marsh and mangrove forests within Everglades National Park. To evaluate changes in ecosystem productivity, we measured temporal patterns of CO2 and the normalized difference vegetation index over the study period. Both water levels and distance from the coast influenced the ecosystem response to low-temperature events. Photosynthetic capacity, or the maximum CO2 uptake rate, and sensitivity to low-temperature events were much higher in mangrove...

Drought is a global issue that is exacerbated by climate change and increasing anthropogenic water demands. The recent occurrence of drought in California provides an important opportunity to examine drought response across ecosystem classes (forests, shrublands, grasslands, and wetlands), which is essential to understand how climate influences ecosystem structure and function. We quantified ecosystem resistance to drought by comparing changes in satellite- derived estimates of water- use efficiency (WUE = net primary productivity [NPP]/evapotranspiration [ET]) under normal (i.e., baseline)...

Wildfire can substantially increase the probability of debris flows, a potentially hazardous and destructive form of mass wasting, in landscapes that have otherwise been stable throughout recent history. Although the exact location, extent, and severity of wildfire or subsequent rainfall intensity and duration cannot be known, probabilities of fire and debris‑flow occurrence for given locations can be estimated with geospatial analysis and modeling. The purpose of this report is to provide information on which watersheds might constitute the most serious potential debris-flow hazards in...

How wildfires are managed is a key determinant of long-term socioecological resiliency and the ability to live with fire. Safe and effective response to fire requires effective pre-fire planning, which is the main focus of this paper. We review general principles of effective federal fire management planning in the U.S., and introduce a framework for incident response planning consistent with these principles. We contextualize this framework in relation to a wildland fire management continuum based on federal fire management policy in the U.S. The framework leverages recent advancements in...

Black carbon (BC) aerosol has relatively short atmospheric lifetimes yet plays a unique and important role in the Earth's climate system, making it an important short-term climate mitigation target. Globally, biomass burning is the largest source of BC emissions into the atmosphere. This study investigated the mass absorption efficiency (MAE) of biomass burning BC generated by controlled combustion of various wildland fuels during the Fire Laboratory at Missoula Experiments (FLAME). MAE values derived from a photoacoustic spectrometer (~7.8 m2/g at a wavelength of 532 nm) were in good...

The response of 28 shrub species to wildfire burn severity was assessed for 8 wildfires on 6 national forests in the northern Rocky Mountains, USA. Stratified random sampling was used to choose 224 stands based on burn severity, habitat type series, slope steepness, stand height, and stand density, which resulted in 896 plots measured at approximately 2-year intervals from 1 to 11 years after the fire. For each species, mathematical models were developed to predict the probability of occurrence on 1/300-acre plots, cover on the plot, and average height. The association between burn...

A greater diversity of native legumes and forbs is desirable for rangeland restoration practice in the Intermountain Region of the western United States. But for such diversity to materialize in the seed marketplace and to be effective in restoration practice, seeds that germinate reliably in seed fields and on restoration sites are needed. We measured germination response of two native legumes, basalt milkvetch (Astragalus filipes Torr. ex A. Gray) and western prairie clover (Dalea ornata [Douglas] Eaton & Wright), after eight germination treatments. Treatments were a factorial combination...

Swiss needle cast (SNC) and its causal organism, Phaeocryptopus gaeumannii, were first detected in New Zealand in 1959 on the North Island near Taupo. Approximately 10 years later, the disease made its first appearance on the South Island (Kimberley et al. 2011). While the environmental factors influencing SNC severity in New Zealand have been well studied (Hood and Kimberley 2005, Stone et al. 2007, Watt et al. 2010, Watt et al. 2011), this study represents the first assessment of population genetic structure and diversity for introduced populations of P. gaeumannii.

The ascomycete fungus Phaeocryptopus gaeumannii is the causal organism of Swiss needle cast (SNC), a foliage disease of Douglas-fir (Pseudotsuga menziesii). The disease was first described in forest plantations in Europe in the 1920s (Boyce 1940). It has since been determined that P. gaeumannii is endemic to western North America and the native range of Douglas-fir in the northwestern United States. Initial assessments of genetic diversity and population structure performed using molecular markers known as single strand conformation polymorphisms (SSCPs) indicated the presence of two...

Swiss needle cast (SNC) is a foliar disease of Douglas-fir (Pseudotsuga menziesii) caused by Phaeocryptopus gaeumannii (Rohde) Petrak. This fungus is endemic to western North America, where it has historically had little impact in native forests. However, increasing disease severity in western Oregon since the 1990s has prompted renewed interest in P. gaeumannii and SNC. For this study, we analyze multilocus microsatellite genotypes from 482 single-spore isolates from 68 trees across 14 sites in the western Coast Range of Oregon and southwestern Washington. This study assesses genotypic...