Treesearch

In a recent article in TREE [1], we reviewed evidence for a consistent standardised estimate of minimum viable populations (MVPs) across taxa [2-4] and found that the universal MVP of 5000 adults advocated by Traill et al. [5] was unsupported by reanalyses of their data. We identified shortcomings in the original analyses, and found substantial uncertainty in standardised MVP estimates, both within populations of the same species and among species. We concluded that neither data nor theory supported a generally applicable MVP.

Curlleaf mountain mahogany (Cercocarpus ledifolius Nutt.) is a little-studied woodland tree that occurs in pure stands throughout the Intermountain West. Stand development and population dynamics of this species are poorly understood, despite their relevance to management. We describe here the development of stand age structures and population dynamics of mahogany woodlands in northern Utah using tree ages and measurements representing five structurally diverse stands. Establishment periods in all stands lasted decades, and regeneration continued intermittently in the absence of stand-repla...

The Range Planting Conservation Practice Standard is used to inform development of Natural Resource Conservation Service (NRCS) management recommendations for improving vegetation composition and productivity of grazed plant communities. Range planting recommendations are generally implemented within an integrated conservation management system in conjunction with related conservation practices such as brush management, prescribed burning, prescribed grazing, herbaceous weed control, and upland wildlife habitat management. The Range Planting Standard is defined as "establishment of adapted...

Broadcast seeding is one of the most widely used post-wildfire emergency response treatments intended to reduce soil erosion, increase vegetative ground cover, and minimize establishment and spread of non-native plant species. However, seeding treatments can also have negative effects such as competition with recovering native plant communities and inadvertent introduction of invasive species. Despite ongoing debates over the efficacy of post-fire seeding and potential negative impacts on natural plant community recovery, seeding remains a widely used stabilization treatment in forested...

Bioenergy production from forest biomass offers a unique solution to reduce wildfire hazard fuel while producing a useful source of renewable energy. However, biomass removals raise concerns about reducing soil carbon and altering forest site productivity. Biochar additions have been suggested as a way to mitigate soil carbon loss and cycle nutrients back into forestry sites; yet, little is known about the effects of intentional biochar amendments to temperate forest soil in conjunction with biomass removals for bioenergy production. In this review, we evaluate the potential for mobile...

In the Southeastern United States, fires in pocosin wetlands and other similar vegetation communities with deep organic soils are a serious concern to fire managers. Highly flammable shrubs, such as gallberry and fetterbush, and small evergreen trees, such as red and loblolly bay, create the potential for extreme surface fire behavior. Moreover, deep organic soils allow excessive ground fire smoldering in these communities. The combustion of organic soils produces large amounts of persistent smoke, which is linked to health concerns and increases the potential for vehicle accidents due to...

Boreal regions comprise about 17% of the global land area, and they both affect and are influenced by climate change. To better understand boreal forest fire emissions and plume evolution, 947 whole air samples were collected aboard the NASA DC-8 research aircraft in summer 2008 as part of the ARCTAS-B field mission, and analyzed for 79 non-methane volatile organic compounds (NMVOCs) using gas chromatography. Together with simultaneous measurements of CO2, CO, CH4, CH2O, NO2, NO, HCN and CH3CN, these measurements represent the most comprehensive assessment of trace gas emissions from...

LANDFIRE is a large interagency project designed to provide nationwide spatial data for fire management applications. As part of the effort, many 2000 vintage Landsat Thematic Mapper and Enhanced Thematic Mapper plus data sets were used in conjunction with a large volume of field information to generate detailed vegetation type and structure data sets for the entire United States. In order to keep these data sets current and relevant to resource managers, there was strong need to develop an approach for updating these products. We are using three different approaches for these purposes....

Volatile organic compounds (VOCs) emitted from fires of biomass commonly found in the southeast and southwest U.S. were investigated with PTR-MS and PIT-MS, which are capable of fast measurements of a large number of VOCs. Both instruments were calibrated with gas standards and mass dependent calibration curves are determined. The sensitivity of the PIT-MS linearly increases with mass, because the ion trap mass spectrometer used in PIT-MS is more efficient for higher masses, whereas the quadrupole in PTR-MS is most efficient around 70 amu. The identification of VOCs in the complicated mix...

We report airborne measurements of emission factors (EF) for trace gases and PM2.5 made in southern Mexico in March of 2006 on 6 crop residue fires, 3 tropical dry forest fires, 8 savanna fires, 1 garbage fire, and 7 mountain pine-oak forest fires. The savanna fire EF were measured early in the local dry season and when compared to EF measured late in the African dry season they were at least 1.7 times larger for NOx, NH3, H2, and most non-methane organic compounds. Our measurements suggest that urban deposition and high windspeed may also be associated with significantly elevated NOx EF....