Treesearch

Ecological indicators provide early warning of adverse environmental change, helping land managers adaptively manage their resources while minimizing costly remediation. In 1999 and 2000, we studied two such indicators, growth and developmental instability, of loblolly pine (Pinus taeda L.) influenced by mechanized infantry training at Fort Benning, Georgia. Disturbed areas were used for military training; tracked and wheeled vehicles damaged vegetation and soils. Highly disturbed sites had fewer trees, diminished ground cover, warmer soils in the summer, and more compacted soils with a...

We tested the hypothesis that changes in leaf area index (LAIm2 m-2) and mean stand diameter following thinning are due to thinning type and residual density. The ratios of pre- to postthinning diameter and LAI were used to assess structural changes between replicated crown, dominant, and low thinning treatments to 33% and 50% residual density in even-aged Picea rubens and Abies balsamea stands with and without a precommercial thinning history in Maine, USA. Diameter ratios varied predictably by thinning type: low thinnings were 0.7 but 1.0 . LAI change was affected by type and intensity...

Host conditions are known to influence spruce beetle population levels, but whether they influence the spatial and temporal patterns of beetle-caused mortality during an outbreak is unknown. Using dendrochronological techniques, we quantified the spatiotemporal dynamics of a modern (late 1980s through the early 2000s) spruce beetle outbreak in Engelmann spruce on the Markagunt Plateau, Utah. Erupting beetle populations occurred in multiple areas across the Plateau over the course of 8 years. Early in the outbreak, the timing of spruce mortality was strongly and predictably related to...

The 1964 Wilderness Act (Public Law 88-577) established the National Wilderness Preservation System "for the protection of these areas, the preservation of their wilderness character" (Section 2a). In congressional testimony clarifying the intent of wilderness designation, Zahniser (1962) said, "The purpose of the Wilderness Act is to preserve the wilderness character of the areas to be included in the wilderness system, not to establish any particular use" (United States Congress 1983), and legal scholars (Rohlf and Honnold 1988, McCloskey 1999) subsequently confirmed that preserving...

Darwin's naturalization hypothesis predicts that successful invaders will tend to differ taxonomically from native species in recipient communities because less related species exhibit lower niche overlap and experience reduced biotic resistance. This hypothesis has garnered substantial support at coarse scales. However, at finer scales, the influence of traits and niche use on invasibility and invader impacts is poorly understood. Within grasslands of western Montana, USA, we compared morphological and phenological traits for five top exotic invasive forbs and five dominant native forbs...

Landscape-scale fire behavior analyses are important to inform decisions on resource management projects that meet land management objectives and protect values from adverse consequences of fire. Deterministic and probabilistic geospatial fire behavior analyses are conducted with various modeling systems including FARSITE, FlamMap, FSPro, and Large Fire Simulation System. The fundamental fire intensity algorithms in these systems require surface fire behavior fuel models and canopy cover to model surface fire behavior. Canopy base height, stand height, and canopy bulk density are required...

This report updates the literature review and synthesis of economic valuation studies on the impacts of forest insect pests by Rosenberger and Smith (1997). A conceptual framework is presented to establish context for the studies. This report also discusses the concept of ecosystem services; identifies key elements of each study; examines areas of future research; and includes appendices that further explain nonmarket valuation methods, a narrative of each study, and tables that summarize each study. The primary services affected by insects are restricted in the literature to include...

The sympycnine genus Telmaturgus Mik is reviewed for the Nearctic region, and includes three species: Telmaturgus parvus (Van Duzee), Telmaturgus robinsoni sp. nov., and Telmaturgus vockerothi sp. nov. Species of Telmaturgus can be recognized by the reduced number of dorsocentral setae (three pairs in Nearctic species) and the projecting lower face of females. Examination of the holotype of T. parvus reveals that the widespread species previously thought to be T. parvus is T. robinsoni. A key to species and comments on the taxonomic history and ecology of the genus are provided.

Even before Arizona was a state, government scientists walked and rode across its broad, open landscapes from nearly sea level to over 12,000 feet of elevation, observing its diverse vegetation and climate. In 1889, biologist C. Hart Merriam traversed northern Arizona and found six of the seven world life zones he would later describe by latitude and elevation. The existence of such varied life zones across such a short distance and a few hundred feet of elevation change fascinated scientists. One particular life zone interested foresters and loggers. Extensive stands of western yellow...

Matrix population models have long been used to examine and predict the fate of threatened populations. However, the majority of these efforts concentrate on long-term equilibrium dynamics of linear systems and their underlying assumptions and, therefore, omit the analysis of transience. Since management decisions are typically concerned with the short term (