Treesearch

We isolated 16 polymorphic microsatellite loci in the mountain pine beetle (Dendroctonus ponderosae Hopkins) and developed conditions for amplifying these markers in four multiplex reactions. Three to 14 alleles were detected per locus across two sampled populations. Observed and expected heterozygosities ranged from 0.000 to 0.902 and from 0.100 to 0.830, respectively. Three loci deviated from Hardy-Weinberg equilibrium in one sampled population. One of these loci may be sex linked. These markers will be useful in the study of population structure in this important pest species.

Considerable research has recently been devoted to understanding biogeochemical processes under winter snow cover, leading to enhanced appreciation of the importance of many winter ecological processes. In this study, a comprehensive investigation of the stable carbon isotope composition (δ 13C) of CO2 within a high-elevation subalpine forest snowpack was conducted. Our goals were to study the δ 13C of biological soil respiration under snow in winter, and to assess the relative importance of diffusion and advection (ventilation by wind) for gas transport within snow. In agreement with...

Inductive inference, the process of drawing general conclusions from specific observations, is fundamental to the scientific method. Platt (1964) termed conclusions obtained through rigorous application of the scientific method as "strong inference" and noted the following basic steps: generating alternative hypotheses; devising experiments, the results of which will exclude one or more hypotheses; conducting the experiment to get a "clean result"; and repeating the process with revision based on the information obtained. Every student is exposed to these basics in introductory courses,...

Understanding how setting attributes influence the nature of the visitor experience is crucial to effective recreation management. Highly influential attributes are useful indicators to monitor within a planning framework, such as Limits of Acceptable Change. This study sought to identify the setting attributes perceived to have the most profound effect on the ability to have "a real wilderness experience" and to assess the degree to which attribute importance varied with situational context and visitor characteristics. To this end, exiting hikers were surveyed at moderate and very high...

Recent studies suggest that the invasive success of Centaurea maculosa< may be related to its stronger allelopathic effects on native North American species than on related European species, one component of the "novel weapons" hypothesis. Other research indicates that C. maculosa plants from the invasive range in North America have evolved to be larger and better competitors than conspecifics from the native range in Europe, a component of the "evolution of increased competitive ability" hypothesis. These hypotheses are not mutually exclusive, but this evidence sets the stage for comparing...

Invasion by exotic species threatens natural ecosystems (Wilcove et al. 1998) and has severe economic ramifications (Pimentel et al. 2000). In many cases, exotic species that form near monocultures in their invaded range are much rarer in their native communities (Lonsdale & Segura 1987; Braithwaite et al. 1989; Malecki et al. 1993; Eckert et al. 1996; Meyer & Florence 1996; Bruce et al. 1997; Paynter et al. 1998; Memmott et al. 2000). Interactions of invasive plants with above-ground enemies (Wolfe 2002; Mitchell & Power 2003), the soil ecosystem (Beckstead & Parker 2003; Reinhart et al....

The purpose of monitoring wilderness character is to improve wilderness stewardship by providing managers a tool to assess how selected actions and conditions related to wilderness character are changing over time. Wilderness character monitoring provides information to help answer two key questions about wilderness character and wilderness stewardship: 1. How is wilderness character changing over time? 2. How do stewardship actions affect this change in wilderness character?

The Wilderness Debate Rages On is a collection of mostly previously published papers about the meaning, value, and role of wilderness and continues the discussion that was propelled by the editors' previous book The Great New Wilderness Debate (also a collection of papers) published in 1998. The editors state that this sequel to their previous book is mandated because "this debate over the concept of wilderness continues to rage" (p. 4). The "debate" in both titles is between those who think that the idea of wilderness is an anachronism that is no longer valid or appropriate in today's...

Studying germination in the native and non-native range of a species can provide unique insights into processes of range expansion and adaptation; however, traits related to germination have rarely been compared between native and nonnative populations. In a series of common garden experiments, we explored whether differences in the seasonality of precipitation, specifically, summer drought vs summer rain, and the amount and variation of annual and seasonal precipitation affect the germination responses of populations of an annual ruderal plant, Centaurea solstitialis, from its native...

A bioclimate model predicting the presence or absence of aspen, Populus tremuloides, in western USA from climate variables was developed by using the Random Forests classification tree on Forest Inventory data from about 118,000 permanent sample plots. A reasonably parsimonious model used eight predictors to describe aspen's climate profile. Classification errors averaged 4.5%, most of which were errors of commission. Themodel was driven primarily by three variables: an annual dryness index, the ratio of summer to annual precipitation, and an interaction of growing season precipitation...