Treesearch

We incubated 196 large-diameter aspen (Populus tremuloides), birch (Betula papyrifera), and pine (Pinus taeda) logs on the FACE Wood Decomposition Experiment encompassing eight climatically-distinct forest sites in the United States. We sampled dead wood from these large-diameter logs after 2 to 6 y of decomposition and determined wood rot type as a continuous variable using the lignin loss/density loss ratio (L/D) and assessed wood-rotting fungal guilds using high-throughput amplicon sequencing (HTAS) of the ITS-2 marker. We found L/ D values in line with a white rot dominance in all...

This study compared oxidative delignification of birch kraft pulp fibers to pulp fibers from acid hydrotropic fractionation (AHF) using p-toluenesulfonic acid (p-TsOH). Under oxygen delignification at 20% consistency, AHF pulps with lower hemicellulose content showed higher delignification than kraft pulps with similar lignin content despite its residual lignin (cellulosic enzymatic lignin, CEL) being less reactive with fewer β-O-4 ether aryl linkages based on 2D13C-1 H nuclear magnetic resonance (NMR) spectroscopy. The water retention value (WRV) of AHF pulp fibers, a measure of fiber...

This chapter reviews the national forest inventories (NFIs) done in Puerto Rico (PR) and the U.S. Virgin Islands (USVI) by discussing the periodic forest inventories of mainland PR (1980-1990) along with the annualized Forest Inventory and Analysis (FIA) program inventories of PR and the USVI (2001-present). Information is offered about the terms and definitions used, current sampling design, processing of data to estimate land area, the equations used for predicting total stem volume and above- and below-ground biomass, results of the most recent forest inventories, data quality control...

Juvenile tree survival will increasingly shape the persistence of ponderosa pine forests in the western United States. In contrast to severe pulse disturbances that induce widespread adult and juvenile tree mortality, moderate periods of low rainfall and warm temperatures may reduce forest persistence by killing juvenile trees at the seedling stage. Intensification of these periods in a changing climate could therefore increasingly restrict both natural regeneration and artificial regeneration of planted seedlings. We conducted a controlled field experiment at a single site in the Front...

Monitoring of tree spatial arrangement is increasingly essential for restoration of dry conifer forests. The presented method was developed for high-density point clouds, like those from unmanned aerial system imagery, to extract and model individual tree location, height, and diameter at breast height (DBH). Extraction of tree locations and heights uses a variable window function searching point cloud-derived canopy height models. Tree DBH is extracted for a subset of point cloud trees using a slice at 1.32-1.42 m and a least-squares circle fitting algorithm. Extracted heights and DBHs...

There is increasing momentum to implement conservation and management approaches that adapt forests to climate change so as to sustain ecosystem functions. These range from actions designed to increase the resistance of current composition and structure to negative impacts to those designed to transition forests to substantially different characteristics. A component of many adaptation approaches will likely include assisted migration of future climate-adapted tree species or genotypes. While forest-assisted migration (FAM) has been discussed conceptually and examined experimentally for...

Uncertainty and emerging threats associated with climate change necessitate the development of new approaches for managing forest ecosystems. To address this need the Adaptive Silviculture for Climate Change (ASCC) Network was established to examine the efficacy of three climate adaptation strategies in important forest types across North America: 1) resistance to change by increasing overstory tree health through reduced inter-tree competition, 2) resilience by creating conditions that allow change within the natural range of variability while encouraging greater abundance of native...

The increasing importance of prescribed fire use has led to an increased focus on the development of modelling tools suited to conditions typical of prescribed fire scenarios. An improved understanding of flame spread through porous surface fuels represents an important part of these efforts. In the lower wind speed conditions typical of many prescribed burns, the role of fuel structure may be of greater importance than in highly wind-aided flame spread scenarios. The porous nature of wildland fuel beds complicates efforts to apply existing, solid surface theories for flame spread in low...

Changes in sulfate (SO42−) deposition have been linked to changes in mercury (Hg) methylation in peatlands and water quality in freshwater catchments. There is little empirical evidence, however, of how quickly methyl-Hg (MeHg, a bioaccumulative neurotoxin) export from catchments might change with declining SO42− deposition. Here, we present responses in total Hg (THg), MeHg, total organic carbon, pH, and SO42− export from a peatland-dominated catchment as a function of changing SO42− deposition in a long-term (1998− 2011), whole-ecosystem, control-impact experiment. Annual SO42− deposition...