Treesearch

Forecasted changes in climate across the southeastern US include an increase in temperature along with more variable precipitation patterns, including an increase in the severity and frequency of drought events. As such, the management of forests for increased resistance or resilience to the direct and indirect effects of climate change, including decreased tree- and stand-level productivity, is of interest to natural resource practitioners. Because the sensitivity of tree growth to climate can be moderated by competition, manipulating stand density through silvicultural activities may...

Reliable dimensional data for old-growth pine-dominated forests in the Gulf Coastal Plain of Arkansas are hard to find, but sometimes unfortunate circumstances provide good opportunities to acquire this information. On July 11, 2013, a severe thunderstorm with high winds struck the Levi Wilcoxon Demonstration Forest (LWDF) near Hamburg, Arkansas. This storm uprooted or snapped dozens of large pines and hardwoods and provided an opportunity to more closely inspect these rare specimens. For instance, the largest tree killed in this event, a loblolly pine (Pinus taeda), was 105 cm in diameter...

Thin-film deposition on ultra-thin substrates poses unique challenges because of the potential for a dynamic response to the film stress during deposition. While theoretical studies have investigated film stress related changes in bulk substrates, little has been done to learn how stress might evolve in a film growing on a compliant substrate. We use silicon nanomembranes (SiNMs), extremely thin sheets of single-crystalline Si, as a substrate for the growth of amorphous SiNx to begin to address this question. Nanomembranes are released from a silicon-on-insulator wafer with selective...

This document originated in 2008 as a collaborative project of the U.S. Fish and Wildlife Service (FWS) and the University of Maryland's Graduate Program in Sustainable Development and Conservation Biology. The original title was A Primer on Climate Change for the National Wildlife Refuge System. The Primer has evolved into Planning for Climate Change on the National Wildlife Refuge System in response to DOl and FWS mandates. In particular, Planning for Climate Change is a Conserving the Future deliverable. The purpose of Planning for Climate Change is to help Refuge System planners and...

Summary 1. The impacts of selective harvesting in tropical forests on population recovery and future timber yields by high-value species remain largely unknown for lack of demographic data spanning all phases of life history, from seed to senescence. In this study, we use an individual- based model parameterized using 15 years of annual census data to simulate population dynamics of big-leaf mahogany Swietenia macrophylla King in southeast Amazonia in response to multiple harvests and in the absence of harvesting. 2. The model is based on regression equations of stem diameter growth,...

Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species’ threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project -- and avert -- future declines. We describe and assess a new database of more than...

The genus Fusarium has a wide host range and causes many different forms of plant disease. These include seed rot and seedling blight diseases of cultivated plants. The diseases caused by Fusarium on wild plants are less well-known. In this study, we examined disease development caused by Fusarium sp. n on nondormant seeds of the important rangeland weed Bromus tectorum as part of broader studies of the phenomenon of stand failure or "die-off" in this annual grass. We previously isolated an undescribed species in the F. tricinctum species complex from die-off soils and showed that it is...

Two new phytotoxic sesquiterpenoid acids, named pyrenophoric acids B and C, were isolated together with the related pyrenophoric and abscisic acids from solid Bromus tectorum (cheatgrass) seed culture of the seed pathogen Pyrenophora semeniperda. This fungus has been proposed as a mycoherbicide for biocontrol of cheatgrass (Bromus tectorum), a Eurasian annual grass that has become invasive in rangelands and is also a serious agricultural weed in the western U.S. Pyrenophoric acids B and C were characterized by spectroscopic methods (NMR and HR ESIMS) as (2Z,4E)-5-[(1R*,4R*,6R*)-1,4-dihydrox...

There are many instances in scholarly activity where the writing of a colleague is made more vivid when one knows him or her personally—and Eric Zenner’s essay is certainly no exception! I can see Eric at a podium of a forestry school in the United States or Europe, emphatically proclaiming that “Silviculture is the pen with which our profession writes, but too often silviculturists have writer’s block!” In this essay, he offers a compelling and entertaining development of the historical perspective of the evolution of silviculture in Europe and North America, especially in reference to...

The Moscow Forestry Sciences Laboratory of the Rocky Mountain Research Station (RMRS) has a unique collection of forest/tree-associated fungi with over 15,000 living specimens. Based in Moscow, ID, this USDA APHIS-PPQ (Plant Protection and Quarantine) containment facility houses fungal archives from approximately 35 states and 30 countries. The collection involves the work of at least 50 USDA Forest Service research scientists and collaborators over the past 30 years. Though the collection primarily focuses on species associated with Armillaria root disease from western North America, it...