Treesearch

We examined small, fishless headwater streams to determine whether transport of macroinvertebrates into the littoral zone of an oligotrophic lake augmented food availability for Cottus asper, an abundant predatory fish in our study system. We sampled fish and macroinvertebrates during the recruitment and growth season of 2 years, either monthly (2004) or bi-monthly (2005), to observe whether stream inputs increased prey availability and whether variation in total macroinvertebrate biomass was tracked by fish. Our results suggest that the effect of fishless headwater streams on downstream...

Recent surveys of belowground fungal biodiversity in Mexico and USA have revealed many undescribed truffle species, including many in the genus Tuber. Here we describe seven new species: Tuber beyerlei, T. castilloi, T. guevarai, T. lauryi, T. mexiusanum, T. miquihuanense and T. walkeri. Phylogenetic analyses place these species within the Maculatum group, an understudied clade of small truffles with little apparent economic value. These species are among the more taxonomically challenging in the genus. We collected Tuber castilloi, T. mexiusanum and T. guevarai as fruit bodies and...

Fungal mitospores may function as dispersal units and/ or spermatia and thus play a role in distribution and/or mating of species that produce them. Mitospore production in ectomycorrhizal (EcM) Pezizales is rarely reported, but here we document mitospore production by a high diversity of EcM Pezizales on three continents, in both hemispheres. We sequenced the internal transcribed spacer (ITS) and partial large subunit (LSU) nuclear rDNA from 292 spore mats (visible mitospore clumps) collected in Argentina, Chile, China, Mexico and the USA between 2009 and 2012. We collated spore mat ITS...

We examine challenges and opportunities involved in applying ecosystem services to public land management with an emphasis on national forests in the United States. We review historical forest management paradigms and related economic approaches, outline a conceptual framework defining the informational needs of forest managers, and consider the feasibility of its application given the types of ecological information typically available and the expanding set of services considered in management decisions. Economists can make their work more relevant to managers by broadening their focus to...

Background: Several recent studies have identified a relationship between the natural environment and improved health outcomes. However, for practical reasons, most have been observational, cross-sectional studies. Purpose: A natural experiment, which provides stronger evidence of causality, was used to test whether a major change to the natural environment—the loss of 100 million trees to the emerald ash borer, an invasive forest pest—has influenced mortality related to cardiovascular and lower-respiratory diseases. Methods: Two fixed-effects regression models were used to estimate the...

Successful infection of coast live oak (Quercus agrifolia Née) stems by Phytophthora ramorum results in the formation of a canker visible initially at the bark surface by the release of a dark red to black colored exudate referred to as "bleeding." Bark and ambrosia beetles are often attracted to diseased trees within the first year after bleeding cankers appear, and bore their gallery entrance holes almost exclusively within the canker boundaries, suggesting the presence of a primary attractant. These attacks accelerate tree mortality. Ethanol concentrations were analyzed in sapwood...

Land conversion and forest fragmentation is an important issue across the country. Forest fragmentation is one of the international Montréal criteria and indicators that the Forest Service, U.S. Department of Agriculture, must assess periodically (Riitters and others 2004). Characteristics of increased fragmentation include increases in the amount of forest-nonforest edge, and decreases in the size of forest patches. Edges are associated with greater drying of forest fuels and the spread of weedy species (both plants and animals). As forest patches become smaller and distances between them...

Yellow-cedar is a culturally, economically, and ecologically important tree in coastal Alaska that has been experiencing a widespread mortality known as yellow-cedar decline for about 100 years. Mapping during annual aerial detection surveys has identified nearly the entire geographical distribution of the problem, which totals over 500,000 acres in Alaska (Lamb and Wurtz 2009) and additional acreage in adjacent British Columbia (Hennon and others 2005). This broad-scale approach to detection has been useful in determining the general occurrence of this forest decline, but mapping from...

As forest carbon offset projects become more popular, professional foresters are providing their expertise to support them. But when several members of the Society of American Foresters questioned the science and assumptions used to design the projects, the organization decided to convene a task force to examine whether these projects can provide the intended climate benefits. The report details reasons to look for other solutions to greenhouse gas emission challenges. After synthesizing the latest available science, the authors challenge the underlying assumptions used to establish most...

Existing models and predictions project serious changes to worldwide hydrologic processes as a result of global climate change. Projections indicate that significant change may threaten National Forest System watersheds that are an important source of water used to support people, economies, and ecosystems. Wildland managers are expected to anticipate and respond to these threats, adjusting management priorities and actions. Because watersheds differ greatly in: (1) the values they support, (2) their exposure to climatic changes, and (3) their sensitivity to climatic changes, understanding...