Treesearch

Mangroves are among the most carbon-rich terrestrial ecosystems, primarily attributable to the soil pool. There are substantial differences in soil carbon (C) and nitrogen (N) due to the disparities in geomorphic settings and ecological drivers, but this insight is drawn primarily from observational studies. An objective inventory of carbon stocks in mangroves of the Rufiji River Delta, Tanzania was conducted. Seventy-five soil cores were collected within a 12,164 ha inventory area, comprising the northern portion of the delta. Cores were collected from intact and dwarf mangroves, agricultu...

All North American ash (Fraxinus spp.) species are threatened by the emerald ash borer(EAB; Agrilus planipennis), an exotic beetle which has already destroyed millions of ash trees in theU.S. and Canada. Although both chemical insecticides and biological control can be effective, andhost resistance appears possible, the speed of the invasion has defied traditional management ap‐proaches. One potential, innovative approach to managing this destructive insect is to develop ahost tree‐induced gene silencing strategy using RNA interference (RNAi) constructs targeting EAB‐specific genes. An...

Pathogens and pests, native or introduced, can cause high levels of damage and mortality in urban and rural forests. In many cases, little can be done to protect standing trees of the affected species; however, there is a growing recognition that host tree resistance can play a role at countering the long-term impacts of such outbreaks. Leveraging tree resistance for forest health requires a commitment to tree breeding such that resistant genotypes can be identified, propagated, and bred to produce resistant populations for replanting the affected species. Successful resistance breeding...

The fields of tree breeding and genetic engineering can be perceived as being antagonistic towards each other—genetic engineers suggesting that tree breeding is too slow and expensive and tree breeders suggesting that genetic engineering is not practical and too expensive. We argue here that both fields have much to offer forestry and the success of each is intimately tied to the other. The major purposes of genetic engineering in forestry are described as well as the importance of evaluating tree engineering initiatives in the context of tree improvement and silviculture and integrating...

Wildfire burned area, fire size, fire severity and the ecological and socio-economic impacts of fire have been increasing rapidly in California in recent decades. We summarize the record-breaking 2020 wildfire season in California statistically, evaluate the drivers of high-severity burning in the 2020 fires and consider implications for fire and resource management.

Changes in atmospheric pressure continuously ventilate soils and snowpacks. This physical process, known as pressure pumping, is a major factor in the exchange fluxes of H2O, CO2, and other trace gases between the soil and atmosphere. Thus models of pressure pumping are relevant to many areas of critical importance. This study compares the three principal models used to describe pressure pumping. Beginning with the fundamental physical principles and whether the flow field is compressible or incompressible, these models are categorized as linear parabolic (one model - compressible) or...

The effect of foam discontinuity in the shear zone of structural insulated panel (SIP) beams was investigated in the current research. Two depths of 15.24 cm and 31.11 cm (6.5 in. and 12.25 in.) SIPs were evaluated in 1/3-point bending. Panels were sawn into beams, each approximately 29.84 cm (11.75 in.) wide, for the mechanical testing. Half of the panels had joints or discontinuities in the foam layer in a location that was subject to shear stress during the bending tests. Half of the panels did not have joints or discontinuities in the foam layer in the locations that were subject to...

Pyrolysis products from wildland fuels are typically measured under tightly controlled conditions using fuels which have been processed to remove water content and physical shape. Different instruments can be used to identify and quantify the composition of these gases. Measurement of pyrolysis gases under conditions typical of wildland fires has seldom occurred. We used FTIR spectroscopy and GC/FID analysis to measure pyrolysis gases produced in wind tunnel experiments and small prescribed burns in longleaf pine needle fuel beds with live shrubs. Use of compositional data techniques on...