Treesearch

Many currently forested areas in the southern Appalachians were harvested in the early 1900s and cleared for agriculture or pasture, but have since been abandoned and reverted to forest (old-field succession). Land-use and land-cover changes such as these may have altered the timing and quantity of water yield (Q). We examined 80 years of streamflow and vegetation data in an experimental watershed that underwent forest–grass–forest conversion (i.e., oldfield succession treatment). We hypothesized that changes in forest species composition and water use would largely explain long-term...

Biological soil crusts are a complex of microscopic organisms growing on the soil surface in many arid and semi-arid ecosystems. These crusts perform the important role of stabilizing soil and reducing or eliminating water and wind erosion. One of the largest threats to biological soil crusts in the arid and semi-arid areas of the western United States is mechanical disturbance from vehicle traffic and grazing. The spread of the annual invasive cheatgrass has increased the fuel load in areas that previously would not carry a fire, posing a potentially widespread and new threat to this...

Ecosystem physical structure, defined by the quantity and spatial distribution of biomass, influences a range of ecosystem functions. Remote sensing tools permit the non-destructive characterization of canopy and root features, potentially providing opportunities to link above- and belowground structure at fine spatial resolution in functionally meaningful ways. To test this possibility, we employed ground-based portable canopy LiDAR (PCL) and ground penetrating radar (GPR) along co-located transects in forested sites spanning multiple stages of ecosystem development and, consequently, of...

Forests can partially offset greenhouse gas emissions and contribute to climate change mitigation, mainly through increases in live biomass. We quantified carbon (C) density in 20 managed longleaf pine (Pinus palustris Mill.) forests ranging in age from 5 to 118 years located across the southeastern United States and estimated above-and belowground C trajectories. Ecosystem C stock (all pools including soil C) and aboveground live tree C increased nonlinearly with stand age and the modeled asymptotic maxima were 168 Mg C/ha and 80 Mg C/ha, respectively. Accumulation of ecosystem C with...

Societies use biologically active chemicals as medicines and pesticides to protect human and agricultural health. But widespread use of synthetic compounds raises concerns about their safety, and resistance development in targeted pests. To find safer alternatives, scientists turned to native plants and trees in Pacific Northwest forests using multiyear exploratory surveys. Researchers collected samples from different plant and tree parts for extraction and toxicity testing with a simple brine shrimp bioassay. These bioassays detected strong biological activity in heartwood extracts from...

Hand-constructed piles in eastern Washington and north-central New Mexico were weighed periodically between October 2011 and June 2015 to develop decay-rate constants that are useful for estimating the rate of piled biomass loss over time. Decay-rate constants (k) were determined by fitting negative exponential curves to time series of pile weight for each site. Piles at the Washington site (k = 0.027/year) decomposed significantly more slowly than piles at the New Mexico site (k = 0.064/year). Significant differences in k for each site may be a function of a between-site variation in pile...

The evapotranspiration / potential evapotranspiration (AET / PET) ratio is traditionally termed as the crop coefficient (Kc) and has been generally used as ecosystem evaporative stress index. In the current hydrology literature, Kchas been widely used as a parameter to estimate crop water demand by water managers but has not been well examined for other types of ecosystems such as forests and other perennial vegetation. Understanding the seasonal dynamics of this variable for all ecosystems is important for projecting the ecohydrological responses to climate change and accurately quantifyin...

This study determined total suspended sediment (TSS) at six stream crossings that represented a range of site conditions and forest operations in the Piedmont of North Carolina. Two wood and three steel bridgemats and one culvert were installed to cross the streams. The road classes for the crossings included four temporary skid trails and two permanent forest haul roads. Baseflow and stormflow water samples and continuous stream discharge were measured using the upstream-downstream approach to determine the effects of stream crossings on TSS concentrations and loads. Upstream and downstrea...

For some volunteers, neighborhood safety is one of the reasons for becoming involved in community greening. For example, many volunteers of the Community Greenspace program at the Urban Resources Initiative in New Haven, Connecticut believe that there is a potential reduction in crime from community greening activities, even though it is not an explicit goal of the program. These types of community-led interventions are distinct from both existing tree canopy and large-scale municipally led initiatives. These types of interventions remain understudied with respect to the potential for...