Treesearch

Extreme, downslope mountain winds often generate dangerous wildfire conditions. We used the wildfire spread model Fire Area Simulator (FARSITE) to simulate two wildfires influenced by strong wind events in Santa Barbara, CA. High spatial-resolution imagery for fuel maps and hourly wind downscaled to 100 m were used as model inputs, and sensitivity tests were performed to evaluate the effects of ignition timing and location on fire spread. Additionally, burn area rasters from FARSITE simulations were compared to minimum travel time rasters from FlamMap simulations, a wildfire model similar...

Local regulations on residential landscapes (yards and gardens) can facilitate or constrain ecosystem services and disservices in cities. To our knowledge, no studies have undertaken a comprehensive look at how municipalities regulate residential landscapes to achieve particular goals and to control management practices. Across six U.S. cities, we analyzed 156 municipal ordinances to examine regional patterns in local landscape regulations and their implications for sustainability. Specifically, we conducted content analysis to capture regulations aimed at: 1) goals pertaining to conservati...

Increasing the sagebrush habitat in the Great Basin Ecoregion remains a management concern for the agencies and conservation organizations within this region. Large-scale removal of the pinyon-juniper woodlands is one method for achieving this objective, particularly in the greater sage grouse (Centrocercus urophasianus) priority areas for conservation (PACs). However, there’s concern that removal of these woodlands will result in a loss of habitat for pinyon-juniper associated bird species to the benefit of sagebrush associated bird species.

Despite a critical need to evaluate effectiveness of forest treatments in improving stand health, practitioners lack quantitative, repeatable metrics to assess tree vigor and stand health. We evaluated canopy and whole tree attributes of ponderosa pine (Pinus ponderosa Dougl. Ex Laws) related to carbon balance, water balance, and susceptibility to insects and pathogens in dry, pine-dominated forest stands during a multi-year drought, an environmental challenge to stand resilience. Metrics of trees in two unmanaged, and seven treated forested stands, in both uplands and lowlands to develop...

Wildland fuels, defined as the combustible biomass of live and dead vegetation, are foundational to fire behavior, ecological effects, and smoke modeling. Along with weather and topography, the composition, structure and condition of wildland fuels drive fire spread, consumption, heat release, plume production and smoke dispersion. To refine inputs to existing and next-generation smoke modeling tools, improved characterization of the spatial and temporal dynamics of wildland fuels is necessary. Computational fluid dynamics (CFD) models that resolve fire–atmosphere interactions offer a...

• The extent to which water availability can be used to predict the enlargement and final dimensions of xylem conduits remains an open issue. • We reconstructed the time course of tracheid enlargement in Pinus sylvestris trees in central Spain by repeated measurements of tracheid diameter on microcores sampled weekly during a 2 yr period. We analyzed the role of water availability in these dynamics empirically through time-series correlation analysis and mechanistically by building a model that simulates daily tracheid enlargement rate and duration based on Lockhart’s equation and water...

The absence of some species from small habitat patches has long posed a challenge for conservationists, yet the underlying mechanisms that cause this "area-sensitivity" remain poorly understood. Capacity of a species to extend their activities into the surrounding matrix habitat represents one potential determinant of area-sensitivity. Species may be able to occupy smaller patches if they can utilize matrix habitat beyond patch boundaries, whereas area-sensitive species may be restricted to larger patches due to their inability to utilize the surrounding matrix. We investigated the...

Understanding the drivers of trait selection is critical for resolving community assembly processes. Here, we test the importance of environmental filtering and trait covariance for structuring the functional traits of understory herbaceous communities distributed along a natural environmental resource gradient that varied in soil moisture, temperature, and nitrogen availability, produced by different topographic positions in the southern Appalachian Mountains. To uncover potential differences in community-level trait responses to the resource gradient, we quantified the averages and...

Catchment mass balance demonstrates the role of hydrologic, pedogenic, and human influences on cycling of Ca, Al, Na, and Si, derived from plagioclase dissolution. As Na is little taken up by vegetation, does not accumulate in secondary soil pools, and is primarily in plagioclase, net Na output is a measure of plagioclase dissolution. Net Na flux is proportional to streamflow, illustrating hydrologic control of weathering. Rates of Ca, Al, and Si release from mineral dissolution are more difficult to evaluate as they are variably taken up by vegetation or stored in secondary soil pools....

The Anthropocene got off to a rough start. Looking back on the 2020s and 2030s, it felt as if the tapestry of ecological and social life was beginning to unravel, slowly at first but then picking up speed. Most of the "unravelling" was driven by climate disruption. World leaders had failed to act decisively -- or at all -- to curb greenhouse gas emissions and make the transition to sustainability earlier in the 21st century. As a result, atmospheric concentrations of greenhouse gases continued to climb and Earth’s average surface temperature edged steadily towards two degrees C (3.6...