Treesearch

Changing fire regimes have the potential to threaten wildlife populations and communities. Understanding species’ responses to novel fire regimes is critical to formulating effective management and conservation strategies in an era of rapid change. Here, we examined the empirical effects of recent and historical wildfire activity on Mexican spotted owl (Strix occidentalis lucida) populations in the southwestern United States. Using region-wide, standardized detection/ non-detection data of Mexican spotted owl breeding pairs collected from 2015 to 2022, we found (i) higher rates of pair...

Non-native- dominated landscapes may arise from invasion by competitive plant species, disturbance and invasion of early-colonizing species, or some combination of these. Without knowing site history, however, it is difficult to predict how native or non-native communities will reassemble after disturbance events. Given increasing disturbance levels across anthropogenically impacted landscapes, predictive understanding of these patterns is important. We asked how disturbance affected community assembly in six invaded habitat types common in dryland, grazed landscapes on Island of Hawai‘i....

Forest managers are searching for better approaches to manage low-value material resulting from fuels management and timber harvest. The conventional practice of slash pile burning emits pollutants and greenhouse gases, and leaves behind burn scars that degrade forest soils and inhibit regeneration of native plants. While sometimes this low-value material can be chipped and removed for beneficial uses elsewhere, such options are costly and logistically difficult on many remote forest sites.Biochar production presents a promising alternative, reducing the need for costly material transport,...

Background: Accurate estimates of available live crown fuel loads are critical for understanding potential wildland fire behavior. Existing crown fire behavior models assume that available crown fuels are limited to all tree foliage and half of the fine branches less than 6 mm in diameter (1 h fuel). They also assume that this relationship is independent of the branchwood moisture content. Despite their widespread use, these assumptions have never been tested, and our understanding of the physiochemical properties that govern live crown flammability and consumption remains limited. To test...

Background: Sagebrush ecosystems are experiencing increases in wildfire extent and severity. Most research on vegetation treatments that reduce fuels and fire risk has been short term (2-3 years) and focused on ecological responses. We review causes of altered fire regimes and summarize literature on the longer-term effects of treatments that modify (1) shrub fuels, (2) pinyon and juniper canopy fuels, and (3) fine herbaceous fuels. We describe treatment effects on fuels, fire behavior, ecological resilience, and resistance to invasive annual grasses.Results: Our review revealed tradeoffs...

Our objective in the present study is to provide basic insights into the coupling between external-gas and solid biomass vegetation processes that control the dynamics of flame spread in wildland fire problems. We focus on a modeling approach that resolves processes occurring at vegetation and flame scales, i.e., the formation of flammable vapors due to the thermal degradation of the solid biomass, the subsequent combustion in ambient air, the thermal feedback to the biomass through radiative and convective heat transfer, and the possible transition from flaming combustion (taking place...

Conservationists increasingly position conservation that is mutually beneficial to people and biodiversity on the promise of empowerment of people through participatory discourse, metrics, processes, and outcomes. Empowerment represents multidimensional concepts and theories that permeate the interlinking levels of power, from the psychological to the political, and social scales in which conservation operates. The multifaceted nature of empowerment makes it challenging to understand, pursue, and evaluate as a central philosophical commitment and goal-oriented practice in conservation....

Increased understanding of how mechanical thinning, prescribed burning, and wildfire affect subsequent wildfire severity is urgently needed as people and forests face a growing wildfire crisis. In response, we reviewed scientific literature for the US West and completed a meta-analysis that answered three questions: (1) How much do treatments reduce wildfire severity within treated areas? (2) How do the effects vary with treatment type, treatment age, and forest type? (3) How does fire weather moderate the effects of treatments? We found overwhelming evidence that mechanical thinning with...

An often-overheard phrase, "there is no future without smoke," describes fire, and associated smoke, as an ecological process inextricably tied to Western forests. While fire can provide many benefits such as reducing fuels and renewing forests, smoke from fires poses a serious challenge to public health, land managers, and air quality regulators. So, can we reduce these challenges?Spanish version: https://research.fs.usda.gov/treesearch/67848

Climate change affects populations over broad geographic ranges due to spatially autocorrelated abiotic conditions known as the Moran effect. However, populations do not always respond to broad-scale environmental changes synchronously across a landscape. We combined multiple datasets for a retrospective analysis of time-series count data (5–28 annual samples per segment) at 144 stream segments dispersed over nearly 1,000 linear kilometers of range to characterize the population structure and scale of spatial synchrony across the southern native range of a coldwater stream fish (brook...