Treesearch

Understanding the dominant soil nitrogen (N) cycling processes in southern Appalachian forests is crucial for predicting ecosystem responses to changing N deposition and climate. The role of anaerobic nitrogen cycling processes in well-aerated soils has long been questioned, and recent N cycling research suggests it needs to be re-evaluated. We assessed gross and potential rates of soil N cycling processes, including mineralization, nitrification, denitrification, nitrifier denitrification, and dissimilatory nitrate reduction to ammonium (DNRA) in sites representing a vegetation and...

We collected data on mortality of late-instar gypsy moth, Lymantria dispar (L.), from outbreak populations over 4 wk in June 2017 at 10 sites in the New England region of the United States, along with estimated rainfall at these sites. Deposition of airborne conidia of the fungal pathogen, Entomophaga maimaiga Humber, Shimazu & R.S. Soper, was measured at these same sites as well as at seven other locations in New England. We also quantified the geographical distribution of gypsy moth-caused defoliation in New England in 2017 and 2018 from Landsat imagery. Weekly mortality of gypsy moth...

In North America the invasive winter moth (Operopthera brumata) has caused defoliation in forest and fruit crop systems in British Columbia, Nova Scotia, Oregon, and in the northeastern United States (the "Northeast"). In the Northeast, it was previously shown that hybridization is occurring with a native congener, Bruce spanworm (O. bruceata)—a species that has a broad distribution across much of North America. Whether hybridization among winter moth and Bruce spanworm populations has occurred in all of regions where winter moth established is unknown. One factor that might influence...

Stream classifications can be used to understand patterns within and across river networks and are most informative when they offer insight into patterns in stream habitat or biology. We developed a classification of Hawaiian stream reaches based on influences of natural landscape features on distributions of stream organisms to understand patterns in ecological potential across five Hawaiian Islands. Our objectives were to (1) identify natural landscape variables strongly associated with species distributions and likely to affect stream habitat; and (2) classify Hawaiian stream reaches...

Fires alter terrestrial dissolved organic carbon (DOC) exports into water, making reliable post-fire DOC monitoring a crucial aspect of safeguarding drinking water supply. We evaluated DOC optical sensors in a pair of prescribed burned and unburned first-order watersheds at the Santee Experimental Forest, in the coastal plain forests of South Carolina, and the receiving second-order watershed during four post-fire storm DOC pulses. Median DOC concentrations were 30 and 23 mg L
1 in the burned and unburned watersheds following the first post-fire storm. Median DOC remained high during the...

The 2011–2014 removal of two large dams on the Elwha River, Washington State, the largest dam removal yet completed globally, created extensive cutbank exposures of reservoir sediments, allowing the first characterization of the facies architecture of sediments through direct observation in reservoirs worldwide and providing an unparalleled opportunity to assess the relationship between environmental influences, such as changes in sediment supply, and their expression in the stratigraphic record. Using a combination of facies description from observation of 49 measured sections and >100...

Wood is one of the primary construction materials used in the United States. However, it is susceptible to decay over time, leading to its reduced service life. Development of targeted wood protection methods requires detailed understanding of microbial wood-decay mechanisms. Fungi are the most destructive microorganisms to attack wood and much research effort has been directed towards understanding their mechanisms of decay. The role of bacteria in wood-decay is less studied. The objective of this research was to compare bacterial communities colonizing pressure-treated and untreated...

USDA Forest Service, Southern and Northern Research Station scientists partnered with the Daniel Boone Forest in Kentucky on a long-term silviculture project focused on enhancing the status of oak in upland hardwood stands under the auspice of the Heathy Forests Restoration Act of 2003. In an attempt to grow small oak natural reproduction into more competitive height classes, we applied herbicide to deaden undesirable midstory trees and to increase sunlight penetrating the forest floor in the first phase of a two-phase shelterwood treatment. We successfully increased the number of larger...

Little is known of the tree and stand dynamics of varied species of planted Paulownia left unmanaged until harvest in the southeastern United States. We sought to remedy this lack of information needed by land managers to make informed decisions by investigating differences in survivorship, attained diameter breast height (DBH), diameter at ground level, total height, tree volume and standlevel volume yields of planted P. elongata, P. fortunei, and P. tomentosa in the cool-moist environment of the southern Appalachian Mountains. After 9 years, combined-species survivorship was only 27.3%....