Treesearch

Climate change is expected to alter the frequency and severity of atmospheric conditions conducive for wildfires. In this study, we assess potential changes in fire weather conditions for the contiguous United States using the Haines Index (HI), a fire weather index that has been employed operationally to detect atmospheric conditions favorable for large and erratic fire behavior. The index summarizes lower atmosphere stability and dryness into an integer value with higher values indicting more fire-prone conditions. We use simulations produced by the North American Regional Climate Change...

Northern white-cedar (Thuja occidentalis) and balsam fir (Abies balsamea.) are co-occurring species in riparian forests of the western Great Lakes region. Throughout much of the region, northern white-cedar has been experiencing population declines due to herbivory by white-tailed deer (Odocoileus virginianus). Preferential browse on northern white-cedar removes seedlings and saplings, allowing balsam fir, as less-preferred browse species, to recruit into larger size classes and potentially out-compete northern white-cedar. There is great interest in restoring and sustaining northern...

Simulating the magnitude and variability of terrestrial methane sources and sinks poses a challenge to ecosystem models because the biophysical and biogeochemical processes that lead to methane emissions from terrestrial and freshwater ecosystems are, by their nature, episodic and spatially disjunct. As a consequence, model predictions of regional methane emissions based on field campaigns from short eddy covariance towers or static chambers have large uncertainties, because measurements focused on a particular known source of methane emission will be biased compared to regional estimates...

Assessment of potential climate change impacts on stream water temperature (Ts) across large scales remains challenging for resource managers because energy exchange processes between the atmosphere and the stream environment are complex and uncertain, and few long-term datasets are available to evaluate changes over time. In this study, we demonstrate how simple monthly linear regression models based on short-term historical Ts observations and readily available interpolated air temperature (Ta) estimates can be used for rapid assessment of historical and future changes in Ts. Models were...

The Lacey Act of 1900 was amended on May 22, 2008, to prohibit the import of illegally sourced plant materials and products manufactured from them into the United States and its territories, and to similarly ban their interstate transport. Trade theory suggests that the effect of the new law would be to reduce the flow of illegally sourced fiber into the United States, increasing prices. Monthly U.S. import data on tropical lumber (January 1989-June 2013) and hardwood plywood (January 1996-June 2013) quantity and unit value were used to estimate alternative statistical models that quantify...

Coarse woody debris (CWD) is an important nursery environment for many tree species. Understanding the communities of ectomycorrhizal fungi (ECMF) and the effect of ECMF species on tree seedling condition in CWD will elucidate the potential for ECMF-mediated effects on seedling dynamics. In hemlock-dominated stands, we characterized ECMF communities associated with eastern hemlock (Tsuga canadensis (L.) Carr) and yellow birch (Betula alleghaniensis Britt) seedling pairs growing on CWD. Seedling foliage and CWD were analyzed chemically, and seedling growth, canopy cover, and canopy species...

Natural disturbances play important roles in shaping the structure and composition of all forest ecosystems and can be used to inform silvicultural practices. Canopy disturbances are often classified along a gradient ranging from highly localized, gap-scale events to stand-replacing events. Wind storms such as downbursts, derechos, and low intensity tornadoes typically result in disturbance that would fall near the center of this gradient and result in intermediate-scale disturbances. Despite their frequency and widespread occurrence, relatively little is known about how intermediate-scale...

Batrachochytrium dendrobatidis (Bd) is a widespread pathogenic fungus that is known to cause the disease, chytridiomycosis, which can be lethal to many amphibians. We compared occurrence rates on spring peepers (Pseudacris crucifer) in urban and forested breeding sites in eastern Texas, USA. All study sites were at approximately the same latitude and altitude, and samples were collected at the same time of year to isolate differences in Bd infection rates between habitat types. We found significant differences (p

Rough mills embody the process of cutting up kiln-dried lumber to components used by discrete wood products manufacturers to manufacture products like furniture, kitchen cabinets, flooring, or other items. Rough mills traditionally have either ripped the lumber first (e.g., the lumber is first cut into strips lengthwise) then cut the strips to the required part lengths or they crosscut the lumber first to part lengths (e.g., cutting the lumber to shorter, full width segments) then ripped the segments to the required part widths. Both processes offer advantages and disadvantages and,...

Altered fuels and climate change are transforming fire regimes in many of Earth's biomes. Postfire reassembly of vegetation - paramount to C storage and biodiversity conservation ­ frequently remains unpredictable and complicated by rapid global change. Using a unique data set of pre and long-term postfire data, combined with long-term data from nearby unburned areas, we examined 10 years of understory vegetation assembly after the 2002 Hayman Fire. This fire was the largest wildfire in recorded history in Colorado, USA. Resistance (initial postfire deviance from prefire condition) and...