Treesearch

Eelgrass (Zostera marina) is the dominant seagrass along the Pacific North American Coast, providing complex physical structure, high trophic productivity, and protection from predators (Phillips 1984; Simenstad 1994). Because of these multiple functions, many fish species and life stages use Eelgrass beds more than other nearshore habitat types (Dean and others 2000; Murphy and others 2000; Johnson and Thedinga 2005). Currently, there is growing evidence identifying nearshore habitats as places that may be regularly inhabitated by large-bodied fish, including sharks (Tobin and others...

Open biomass burning is a significant source of primary air pollutants such as particulate matter (PM) and non-methane organic gases (NMOG). However, the physical and chemical atmospheric processing of these emissions during transport is poorly understood. Atmospheric transformations of biomass burning emissions have been investigated in environmental chambers, but there have been limited opportunities to investigate these transformations in the atmosphere. In this study, we deployed a suite of real-time instrumentation on a Twin Otter aircraft to sample smoke from prescribed fires in...

Annual rings are not commonly produced in tropical trees because they grow in a relatively aseasonal environment. However, in the subalpine zones of Hawai‘i's highest volcanoes, there is often strong seasonal variability in temperature and rainfall. Using classical dendrochronological methods, annual growth rings were shown to occur in Sophora chrysophylla, a native tree species on Maunakea, Hawai‘i. Chronologies were established from nearby non-native, live conifer trees and these were used to verify the dates from a total of 52 series from 22 S. chrysophylla trees, establishing an 86-y...

Atmospheric acid deposition of sulfate and nitrate has declined markedly in the northeastern United States due to emissions controls. We investigated long-term trends in soil water (1984–2011) and stream water (1982–2011) chemistry along an elevation gradient of a forested watershed to evaluate the progress of recovery of drainage waters from acidic deposition at the Hubbard Brook Experimental Forest in the White Mountains of New Hampshire, USA. We found slowed losses of base cations from soil and decreasedmobilization of dissolved inorganic aluminum. Stream water pH at the watershed...

Past studies have documented differences in epicuticular wax among several tree species but little attention has been paid to changes in accumulation of foliar wax that can occur during the year. We sampled current-year needles from the terminal shoots of Douglas-fir (Pseudotsuga menziesii var. menziesii) in late June/early July, late August and early November. Needles were sampled from two sites that differed in their climate and shoot phenology. Adaxial (upper), abaxial (lower) and cross-sectional surfaces were examined on scanning electron micrographs. Wax thickness increased significant...

Emerald ash borer (EAB), a non-native invasive tree-boring beetle, is the primary agent behind thewidespread mortality of ash trees (Fraxinus spp.) in both natural forests and urban areas of North Amer-ica. While a variety of insecticide options have been adopted for protection against EAB attacks, little hasbeen reported on the success of insecticide treatments on EAB-infested trees. This is particularly impor-tant because EAB is difficult to detect in early stages of its infestation and protective treatment may beundertaken on trees already in decline. Here, we investigated the effectiven...

Plant responses to ozone (O3) and water deficit (WD) are commonly observed, although less is known about their interaction. Stomatal conductance (gs) is both an impact of these stressors and a protective response to them. Stomatal closure reduces inward flux of O3 and outward flux of water. Stomatal measurements are generally obtained at midday when gas exchange is maximal, but these may not be adequate surrogates for stomatal responses observed at other times of day, nor for non-stomatal responses. Here, we find in Pima cotton that stomatal responses to O3 observed at midday do not...

This paper presented construction and strain distributions for light-weight wood-fiber-based structural panels with tri-grid core made from phenolic impregnated laminated paper composites under bending. A new fastening configuration of slots in the faces and tabs on the core was applied to the face/core interfaces of the sandwich panel in addition to epoxy resin. Both normal strain gages and shear strain gages were attached on these panels to analyze inside strain distributions by third point load bending test. The purpose of the bending test was to investigate the various strain distributi...

Reforestation of mined land in the Appalachians realizes many important benefits and provides important ecosystem services. Because much of the reclaimed mine lands in Appalachia were previously in forest, reclaiming these drastically disturbed areas to forests is desirable, feasible and cost-effective. The Forestry Reclamation Approach (FRA) provides a five-step procedure to achieve successful mine land reforestation (Burger et al. 2005, Zipper et al. 2011). Because high tree species diversity is a hallmark of the Appalachian forest, one of the steps of the FRA is to reforest the site...