Treesearch

Forecasting the spread and potential impacts of invasive, alien species is vital to relevant management and policy decisions. Models that estimate areas of potential suitability are useful to guide early detection and eradication, inform effective budget allocations, and justify quarantine regulations. Machine-learning is a rapidly emerging technology with myriad applications, including the analysis of factors that govern species’ distributions. However, forecasts for invasive species often require extrapolation into novel spaces, which may severely erode model reliability. Using the...

Recent research indicates that non-orthogonal sonic anemometers underestimate vertical wind velocity and consequently eddy-covariance fluxes of mass and energy. Whether this is a general problem among all non-orthogonal sonic anemometers, including those calibrated for flow-shadowing effects, is unknown. To investigate this, we test two sonic anemometer designs, orthogonal (3Vx-probe, Applied Technologies, Inc.) and non-orthogonal (R3-50, Gill Instruments, Ltd.), in a series of field manipulation experiments featuring replicate instruments mounted in various orientations, and use a...

Fire mosses, including Ceratodon purpureus, Funaria hygrometrica and Bryum argenteum, can achieve high cover within months to years after high-severity fire, but do so heterogeneously across space and time. We conducted a survey of moss cover and erosion-related functions after 10 wildfires in Pinus ponderosa and mixed-conifer forests of the southwestern USA. We sampled 65 plots in high-severity patches, stratifying by elevation and insolation over each fire. Using three landscape-scale predictor variables and one temporal predictor, we explained 37% of the variance in fire moss cover...

Present-day eddy-covariance-based methods for measuring the energy and mass exchange between the earth's surface and the atmosphere often do not close the surface energy balance. Frequently the turbulent energy fluxes (sum of sensible and latent heat) underestimate the available energy (net incoming radiation minus the soil conductive heat flux) by 10 % to 20 % or more. Over the last 3 or 4 decades several reasons for this underestimation have been proposed, but nothing completely definitive has been found. This study examines the contribution of two rarely discussed aspects of atmospheric...

U.S. federal government agencies play an important role in mitigating some risks posed to communities by natural hazard events, especially communities with high proportions of low-income or minority residents. Ongoing efforts of the U.S. Forest Service (USFS) to reduce the buildup of forest fuels on national forests, particularly in dry mixed-conifer forests of the U.S. West, are an example. Federal land management agencies must comply with the Executive Order on Environmental Justice (EJ Order, 59 Fed. Reg 7629, 1994), but there is scant documentation of whether these agencies have...

The FLUXNET2015 dataset provides ecosystem-scale data on CO2, water, and energy exchange between the biosphere and the atmosphere, and other meteorological and biological measurements, from 212 sites around the globe (over 1500 site-years, up to and including year 2014). These sites, independently managed and operated, voluntarily contributed their data to create global datasets. Data were quality controlled and processed using uniform methods, to improve consistency and intercomparability across sites. The dataset is already being used in a number of applications, including ecophysiology...

In Southern California, the Santa Ana winds are famous for their role in spreading large wildfires during the fall/winter season. Combined with Southern California's complex topography, Santa Anas create challenges for modeling wind-fire relationships in this region. Here, we assess heterogeneity of winds during Santa Ana and non-Santa Ana days, on days with and without large-fire ignitions, across a modern high-density observational network of 30 meteorological stations. Wind speeds on Santa Ana days with a large fire ignition (mean windspeed = 5.19 m/s) are significantly higher than on...

Following a wildfire, regeneration to forest can take decades to centuries and is no longer assured in many western U.S. environments given escalating wildfire severity and warming trends. After large fire years, managers prioritize where to allocate scarce planting resources, often with limited information on the factors that drive successful forest establishment. Where occurring, long-term effects of postfire salvage operations can increase uncertainty of establishment. Here, we collected field data on postfire regeneration patterns within 13- to 28-yr-old burned patches in eastern...

Climate warming is increasing fire activity in many of Earth’s forested ecosystems. Because fire is a catalyst for change, investigation of post-fire vegetation response is critical to understanding the potential for future conversions from forest to non-forest vegetation types. We characterized the influences of climate and terrain on post-fire tree regeneration and assessed how these biophysical factors might shape future vulnerability to wildfire-driven forest conversion.

Global climate change presents a growing conservation threat, but our understanding of the effects of climate change remains limited for most species. We evaluated the annual climate cycle for threatened Mexican Spotted Owls (Strix occidentalis lucida) in high-elevation mixed-conifer forests in the Sacramento Mountains of New Mexico from 2005 to 2010. We used data from a network of weather stations in Mexican Spotted Owl habitat to describe annual temperature cycles, and precipitation data from a National Weather Service weather station to describe the annual precipitation cycle. We...