Treesearch

Subalpine meadows are some of the most ecologically important components of mountain landscapes, and primary productivity is important to the maintenance of meadow functions. Understanding how changes in primary productivity are associated with variability in moisture and temperature will become increasingly important with current and anticipated changes in climate. Our objective was to describe patterns and variability in aboveground live vascular plant biomass in relation to climatic factors. We harvested aboveground biomass at peak growth from four 64-m2 plots each in xeric, mesic, and...

Wilderness managers are charged with the challenging goal of balancing resource protection and experience quality across a broad, value-laden landscape. While research has provided insight into visitors' motivations and their meanings for wilderness, a struggle exists to implement experiential concepts within current management frameworks. This research posits the human experience of wilderness to be an evolving, enduring relationship, and that research needs can be addressed by conceptualizing and investigating an individuals' personal wilderness relationship. The purpose of this study...

Factors influencing tree growth in structurally complex forests remain poorly understood. Here we assessed the influence of competition on Pinus resinosa (n = 224) and Pinus strobus (n = 90) growth in four old-growth stands in Minnesota, using mixed effects models. A subset of trees, with accurate age estimates, was used to further test the influence of tree age. Our analyses included the weighted Voronoi diagram (WVD) as a novel competition index, representing a detailed description of the spatial structure of a tree's neighborhood. Competition was variably expressed depending on stand...

We summarized all known historical and contemporary data on the geographic distribution of Etheostoma raneyi (Yazoo Darter), a range-restricted endemic in the Little Tallahatchie and Yocona rivers (upper Yazoo River basin), MS. We identified federal and state land ownership in relation to the darter’s distribution and provided quantitative estimates of abundance of the species. We also quantified sex ratio and mean size of males and females, summarized abiotic and physical characteristics of streams supporting the species, and characterized the fish assemblage most often associated with...

Four new species of Coenogonium are described from the Caribbean island of Puerto Rico—C. aurantiacum Mercado-Díaz & Lucking, C. borinquense Mercado-Díaz & Lucking, C. dimorphicum Mercado-Díaz & Lucking and C. portoricense Mercado-Díaz & Lucking. All were discovered in small and highly fragmented forest remnants of relatively rare Puerto Rican forest ecosystems, Pterocarpus wetlands and noncalcareous dry forests. The discoveries are discussed relative to the conservation status of these threatened ecosystems, the need to catalogue biodiversity before it vanishes, and the notion that...

Target 2 of the 2020 Global Strategy for Plant Conservation (GSPC) calls for a comprehensive list of the world’s threatened plant species. The lack of such a list is one of the greatest impediments to protecting the full complement of the world’s plant species, and work to achieve this has been slow. An efficient system for identifying those species that are at risk of extinction could help to achieve this goal in a timeframe sensitive to today’s conservation needs. Two systems that efficiently use available data to assess conservation status were tested against a provisional International...

There is significant interest in silvicultural systems such as variable retention harvesting (VRH) that emulate natural disturbance and increase structural complexity, spatial heterogeneity, and biological diversity in managed forests. However, the consequences of variable retention harvesting for new cohort growth and survival are not well characterized in many forest ecosystems. Moreover, the relative importance of resource preemption by existing ground layer vegetation after variable retention harvests is unclear. We addressed both in a VRH experiment implemented as a randomized block...

Humid tropical forests play a dominant role in many global biogeochemical cycles, yet long-term records of tropical stream chemistry and its response to disturbance events such as severe storms and droughts are rare. Here we document the long-term variability in chemistry of two streams in the Luquillo Mountains, Puerto Rico over a period of 27 years. Our two focal study watersheds, the Rio Icacos and Quebrada Sonadora, both drain several hundred hectares of tropical wet forests, and each received direct hits from Hurricanes Hugo (1989) and Georges (1998). They differ primarily in lithology...

Bark beetles (Coleoptera: Curculionidae, Scolytinae) are important tree mortality agents in western coniferous forests. Protection of individual trees from bark beetle attack has historically involved applications of liquid formulations of contact insecticides to the tree bole using hydraulic sprayers. More recently, researchers have examined the effectiveness of injecting small quantities of systemic insecticides directly into trees, but early efforts were largely unsuccessful. In this study, we determine the efficacy of fall (16-18 September) injections of abamectin (Abacide™ 2Hp; Mauget...

SPLAT® (Specialized Pheromone and Lure Application Technology) emulsion is a unique controlled-release technology that can be adapted to dispense and protect a wide variety of compounds from degradation, including semiochemicals, pesticides, and phagostimulants, in diverse environments. ISCA Technologies, Inc., in collaboration with colleagues in academia, government, and industry, has been developing SPLAT®-based insect control products for close to a decade. This chapter provides an overview of SPLAT® technology and existing commercial formulations and describes ongoing efforts to...