Treesearch

The oomycete Aphanomyces astaci is an emerging infectious pathogen affecting freshwater crayfishworldwide and is responsible for one of the most severe wildlife pandemics ever reported. Thepathogen has caused mass mortalities of freshwater crayfish species in Europe and Asia, and threatensother susceptible species in Madagascar, Oceania and South America. The pathogen naturally coexistswith some North American crayfish species that are its chronic carriers. Presumptions that A. astacioriginated in North America are based on disease outbreaks that followed translocations of NorthAmerican...

Tropical savanna ecosystems play a major role in the seasonality of the global carbon cycle. However, their ability to store and sequester carbon is uncertain due to combined and intermingling effects of anthropogenic activities and climate change, which impact wildfire regimes and vegetation dynamics. Accurate measurements of tropical savanna vegetation aboveground biomass (AGB) over broad spatial scales are crucial to achieve effective carbon emission mitigation strategies. UAV-lidar is a new remote sensing technology that can enable rapid 3-D mapping of structure and related AGB in...

Extreme wildfires are a major environmental and socioeconomic threat across many regions worldwide. The limits of fire suppression-centred strategies have become evident even in technologically well-equipped countries, due to high-cost and a legacy of landscape transformations, yet with ultimately low-efficient solutions vis- `a-vis extreme fires. Many practitioners and policymakers thus increasingly recognize the need to develop novel, integrated fire management approaches that shift emphasis towards the root causes of extreme fires. Here we provide from the socioeconomic angle a collectiv...

In forest canopies, it is common to perform leaf-level gas-exchange measurements on recently excised branches, often without testing for excision-related biases. We conducted a formal test of excision effects using gas-exchange measurements from cut and uncut canopy branches of three deciduous hardwoods – sugar maple (Acer saccharum Marsh.), tulip poplar (Liriodendron tulipifera L.), and white oak (Quercus alba L.). Across all species, excision immediately reduced photosynthesis and stomatal conductance by 27–62% relative to pre-excision rates. In white oak, which had particularly long (>...

Black ash (Fraxinus nigra) wetlands are widespread, forested landscape features in the western Great Lakes region. However, the future of these ecosystems is threatened due to impending spread of the invasive emerald ash borer (EAB), which results in tree mortality, decreased transpiration, and potential shifts to wetter, non-forested conditions. The vulnerability to such ecohydrologic shifts likely varies according to local hydrologic regimes controlled by landscape settings, but this site-dependent vulnerability and our ability to predict it is unknown. Here, we assessed vulnerability...

Specific heat capacity of eleven live foliar fuels from the southeastern United States was measured to 434 ◦C using differential scanning calorimetry to improve the modeling of prescribed fire behavior. Techniques which allow measurement of the standard heat capacity, excluding the effects of heat of reaction, were refined. Specific heat of leaves increased with temperature until the onset of pyrolysis. Once pyrolysis began, the specific heat became nearly constant. We present a simple model, suitable for incorporation in computer simulations, which captures this functional shape. This...

Community-based forest management has become increasingly widespread in Africa since the 1990s as an approach to conserving local forests while contributing social and economic benefits to local communities. Community forests (CFs) can sell forest goods and services to generate revenue for community benefit. Increased understanding of whether and how CFs can be economically viable is important for assessing their potential to alleviate rural poverty and deliver benefits to local communities. Questions of viability of commercial timber-producing CFs largely have not been addressed to date...

Chaparral shrublands are the dominant wildland vegetation type in Southern California and the most extensive ecosystem in the state. Disturbance by wildfire and climate change have created a dynamic landscape in which biomass mapping is key in tracking the ability of chaparral shrublands to sequester carbon. Despite this importance, most national and regional scale estimates do not account for shrubland biomass. Employing plot data from several sources, we built a random forest model to predict aboveground live biomass in Southern California using remote sensing data (Landsat Normalized...

The objectives of this study are to evaluate landscape-scale fuel and terrain controls on fire rate of spread (ROS) estimates derived from repetitive airborne thermal infrared (ATIR) imagery sequences collected during the 2017 Thomas and Detwiler extreme wildfire events in California. Environmental covariate data were derived from prefire National Agriculture Imagery Program (NAIP) orthoimagery and USGS digital elevation models (DEMs). Active fronts and spread vectors of the expanding fires were delineated from ATIR imagery. Then, statistical relationships between fire spread rates and...

Anthropogenic nitrogen (N) and sulfur (S) deposition can negatively affect ecosystem functions and lichen biomonitors can be a cost-effective way to monitor air pollution exposure across the landscape. Interior dry forests of the southwestern United States face increasing development pressures; however, this region differs from others with well-developed biomonitoring programs in having drier climates and a greater fraction of deposition delivered in dry forms. We measured throughfall N and S deposition at 12 sites in Utah and 10 in New Mexico and co-located collection of 6 lichen species....