Treesearch

The annual national report of the Forest Health Monitoring (FHM) Program of the Forest Service, U.S. Department of Agriculture, presents forest health status and trends from a national or multi-State regional perspective using a variety of sources, introducesnew techniques for analyzing forest health data, and summarizes results of recently completed Evaluation Monitoring projects funded through the FHM national program. In this 16th edition in a series of annual reports, survey data are used to identify geographic patterns of insect and disease activity. Satellite data are employed to...

Winter survivorship of insects is determined by a combination of physiological, behavioral, and microhabitat characteristics. We characterized the cold tolerance of the walnut twig beetle, Pityophthorus juglandis Blackman, a domestic alien invasive bark beetle that vectors a phytopathogenic fungus. The beetle and fungus cause thousand cankers disease in species of Juglans and Pterocarya. The disease is spreading in the United States of America (USA) and Italy. Contact thermocouple thermometry was used to measure the supercooling points of adults and larvae and lower lethal temperatures of...

Most land plants acquire nitrogen (N) through associations with arbuscular (AM) and ectomycorrhizal (ECM) fungi, but these symbionts employ contrasting strategies for N acquisition, which may lead to different stocks of soil carbon (C). We experimentally test this hypothesis with a mesocosm system where AM and ECM tree seedling roots, or their hyphae only, could access mineral soils with 13C- and 15N-enriched organic matter. We quantified loss of soil C and N, plant uptake of N and new inputs of plant C to soil. We found that AM, but not ECM, seedlings reduced soil C relative to controls....

In steep soil-mantled landscapes, the initiation of shallow landslides is strongly controlled by the distribution of vegetation, whose roots reinforce the soil. The magnitude of root reinforcement depends on the number, diameter distribution, orientation and the mechanical properties of roots that cross potential failure planes. Understanding how these properties vary in space and time in forests remains a significant challenge. Here we test the hypothesis that spatio-temporal variations in root reinforcement along a hillslope occur as a function of topographic soil moisture gradients. To...

Resource subsidies and biodiversity are essential for maintaining community structure and ecosystem functioning, but the relative importance of consumer diversity and resource characteristics to decomposition remains unclear. Forested headwater streams are detritus-based systems, dependent on leaf litter inputs from adjacent riparian ecosystems, and decomposition of these resources is an important ecosystem function. Here, we examined the effects of consumer community diversity on leaf decomposition in a reciprocal transplant experiment. We asked (1) whether stream consumer communities are...

In the late 19th century, virgin southern pine forests in the West Gulf Coast Region remained virtually untouched. After the Civil War, this land was made available by the government for homesteading and sale. Pine timberland was offered for sale at $1.25 per acre. Primarily northern lumbermen and land speculators purchased the land. Lumbering then became the economic driver for the recovery of the region. By the end of the first quarter of the 20th century, only isolated pockets of the old-growth forests remained. Landscapes once covered with majestic stands of virgin longleaf pines had...

Periodic introductions of the Asian subspecies of gypsy moth, Lymantria dispar asiatica Vnukovskij and Lymantria dispar japonica Motschulsky, in North America are threatening forests and interrupting foreign trade. Although Asian gypsy moth has similar morphology to that of European and North American gypsy moth, it has several traits that make it a greater threat, the most important being the flight capability of females. Asian gypsy moth is not yet established in North America; however, infestations have been detected multiple times in Canada and the United States. To facilitate detection...

High-quality black walnut (Juglans nigra L.) logs are of great economic value and are used in the manufacture of high-end products. Indigenous to the central hardwood region, black walnut has been commercially cultivated for many years, and genetic improvement and selections have resulted in superior timber genotypes. The recalcitrance of black walnut cuttings to form adventitious roots is the greatest hurdle for mass propagation of improved material. The goal of this research was to improve the frequency of adventitious root formation in black walnut cuttings, and investigate anatomical...