Treesearch

Concern over the effects of removing fire-scarred partial cross-sections may limit sampling of live ponderosa pine to reconstruct fire history. We report mortality rates for ponderosa pine trees 20 to 21 years after removing fire-scarred partial cross-sections to reconstruct fire history. In 2015, following surveys every five years since 2000, we revisited 138 trees that were alive when we sectioned them in 1994/95 and 386 similarly sized, un-sectioned neighbor trees of the same species that were also alive in 1994/95. Between 1994/95 and 2015, a significantly greater proportion of...

This study presents a comprehensive review of estimated black carbon (BC) emissions in Russia from a range of studies. Russia has an important role regarding BC emissions given the extent of its territory above the Arctic Circle, where BC emissions have a particularly pronounced effect on the climate. We assess underlying methodologies and data sources for each major emissions source based on their level of detail, accuracy and extent to which they represent current conditions. We then present reference values for each major emissions source. In the case of flaring, the study presents new...

One of the major science gaps in U.S. wildfire policy is the lack of studies on the long-term benefits of hazardous fuel reduction and restoration programs. For instance, there is little information available to predict the impact of current fuel management and restoration on wildfire activity and whether these fuel reduction activities will meet expectations in terms of wildfire risk to social, ecological, and economic values on national forests. To address this gap, we built a new model that uses the Forest Vegetation Simulator Parallel Processing Extension and FSim large wildfire...

Drylands occupy almost 50% of the Earth’s surface and are increasingly affected by extensive land uses such as grazing. These practices affect multiple biotic and abiotic interactions mainly through loss of habitat and resources available for native wildlife. We examined the effects of local vegetation conditions on resource selection by a small mammal species in drylands with different resource availability. The study was conducted in a semi-arid woodland that included an area protected from livestock grazing and human settlement for more than 50 years, the Man and the Biosphere Ñacunán...

This paper introduces a concentrated di-carboxylic acid (DCA) hydrolysis process for the integrated production of thermally stable and carboxylated cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs). The DCA hydrolysis process addressed several issues associated with mineral acid hydrolysis for CNC production, such as cellulose loss and acid recovery. The surface and morphological properties of the cellulose nanomaterials resulting from the DCA hydrolysis process can be tailored simply by controlling the severity of DCA hydrolysis. To further reduce cost, a low temperature...

In this chapter, we present recent advances in the multi-scale data-driven inverse constitutive characterization of composites via multi-axial robotic testing, high-performance full-field strain measurement methods and surrogate models. Emphasis is given first on the motivating aspects for multi-scale model inversion for the case of laminated composites, followed by a description of a data-driven inverse constitutive characterization of the bulk lamina of composites via multi-axial loading of laminate-level coupons. A description of a surrogate modeling approach is presented in order to...

Long-term declines in northern bobwhite (Colinus virginianus) in the United States are presumably due to decades of habitat loss or degradation at a national scale. Food and fiber production characterized by replacement of open woodlands and savannas by dense forest, intensification of agriculture, and conversion of native grasslands to nonnative pastures have degraded habitats for most grassland and early successional birds. Declines in bobwhite and associated species occurred within this context at a scale that has overwhelmed wildlife management efforts. However, with understanding of...

Mercury (Hg) methylation is often elevated at the terrestrial–peatland interface, but methylmercury (MeHg) production at this “hot spot” has not been linked with in situ biotic accumulation. We examined total Hg and MeHg levels in peat, invertebrates and tissues of the insectivore Sorex cinereus (masked shrew), inhabiting a terrestrial–peatland ecotone in northern Minnesota, USA. Mean MeHg concentrations in S. cinereus (71 ng g−1) fell between concentrations measured in spiders (mean 70–140 ng g−1), and ground beetles and millipedes (mean 29–42 ng g−1). Methylmercury concentrations in S....

Studies on the dependence of the rates of ecosystem gas exchange on environmental parameters often rely on the up-scaling of leaf-level response curves ('bottom-up' approach), and/or the down-scaling of ecosystem fluxes ('top-down' approach), where one takes advantage of the natural diurnal covariation between the parameter of interest and photosynthesis rates. Partly independent from environmental variation, molecular circadian clocks drive ∼24 h oscillations in leaf-level photosynthesis, stomatal conductance and other physiological processes in plants under controlled laboratory condition...

The formation of carbon-based nanomaterials was investigated through heating iron nitrate promoted kraft lignin at different temperatures up to 600°C under argon gas at atmospheric pressure. High-resolution transmission electron microscopy and electron diffraction images showed that multi-layer turbostratic-structured graphene presented in samples heated at 600°C. X-ray diffraction results indicated that iron oxides nanoparticles started their formation as an amorphous carbon matrix at 300°C, and turned into α-Fe nanoparticles at 600°C. It is believed that the formation of observed...