Treesearch

One concept in geomorphology is that vegetation is a fundamental control on sediment and water supplies to streams and, therefore, on downstream fluvial processes and channel morphology. Within this paradigm, wildfire has been implicated as a major driving force behind landscape erosion and changes to stream channels, periodically yielding pulses of sediment from uplands that may drive changes to stream channels. However, channel response to wildfire has not been well studied over long periods (>10 years), and the occurrence and nature of long-term changes in channel characteristics remain...

In 2000, a collaborative rangeland monitoring program was established with the University of Arizona, Gila County Cattlegrowers, and the Tonto National Forest. Dutchwoman Butte (DWB) is an isolated, ungrazed 40 ha mesa with relict vegetation. Our objective was to contrast the vegetation of DWB to that of a grazed site, Whiskey tank (WT), across multiple years (2001, 2003, 2004, and 2005). Data were collected for plant frequency, botanical composition (dry weight rank procedure), ground cover, and distance to the nearest perennial plant base (fetch).

Numerous wildfires in recent years have highlighted managers' needs for reliable tools to predict postfire mortality of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) trees. General applicability of existing mortality models is uncertain, as researchers have used different sets of variables. We quantified tree attributes, crown and bole fire damage, ground fire severity, and insect presence from a total of 5,083 trees in four 2000 wildfires in four Intermountain states. Crown scorch (percentage) and consumption (percentage) volume collectively accounted for the majority of predictive...

Fire frequency and severity, and vegetation composition and structure have been altered across much of North America during the past century because of fire exclusion and other land management practices. The cumulative results are now recognized to be partly responsible for dramatic increases in wildland fire severity and declines in ecosystem health. In response, the Departments of Agriculture and Interior are developing a strategy for reducing fire hazard and restoring forest health. A key component of this strategy is the assessment of the departure of current plant communities from...

Despite the widespread use of underwater observation to census stream-dwelling fishes, the accuracy of snorkeling methods has rarely been validated. We evaluated the efficiency of day and night snorkel counts for estimating the abundance of bull trout Salvelinus confluentus in 215 sites within first- to third-order streams. We used a dual-gear approach that applied multiple-pass electrofishing catch data adjusted for capture efficiency to estimate true or baseline fish abundance. Our multiple-pass electrofishing capture efficiency models were based on a prior study and used recapture data...

This comprehensive guide focuses on restoration of small-scale impact caused by human actions in wilderness and backcountry areas. The guide's goals are to: 1) Help practitioners develop plans that thoroughly address the question of whether site restoration is the best management action and, if so, develop a site-specific restoration plan that incorporates ecological concepts and addresses patterns of human use. 2) Provide the latest information on site-specific restoration techniques, including site preparation, soil amendments, planting, mulching, and so forth. 3) Explore the various...

Meeting national goals for hazardous fuels reduction and ecosystem restoration would be difficult - if not impossible - without utilizing prescribed fire. Suspension of prescribed fire programs, as often happens following an escape, limits Federal capacity to meet programmatic, social, and ecological goals.

We used six polymorphic microsatellite loci to analyze the population genetic structure of bull trout Salvelinus confluentus in the Boise River, Idaho, and we compared our results with previous data from similarly sized river systems in western North America. Within the Boise River, we found low genetic variation within and significant differentiation among sample sites. Two cohesive groups of populations were associated with the two major subbasins in this system, which we attributed to long-term reduction of gene flow or distinct sources of colonization at this scale. We observed a...

Oak wilt (Ceratocystis fagacearum), a fungal disease that causes some species of oak trees to wilt and die rapidly, is a threat to oak forested resources in 22 states in the United States. We developed a methodology for predicting the Potential Distribution of Oak Wilt (PDOW) using Anoka County, Minnesota as our study area. The PDOW utilizes GIS; the classification tree statistical test; field sample data; commonly acquired, coarse-resolution auxiliary data; and a unique application of data from the Landsat Thematic Mapper (TM) satellite to predict the spatial distribution of oak wilt. Two...

As water shortages persist throughout the Western U.S., a great deal of money and effort is directed toward decreasing riparian water loss, thereby enabling continued water use by irrigators, industry, and municipalities. This study focuses upon long-term measurement of evapotranspiration (ET) by native and non-native riparian species along the Middle Rio Grande (MRG) in New Mexico where riparian ET has been estimated to be 20 to 50 percent of water budget depletions. Leaf area index (LAI) was most strongly related to average ET rates, irrespective of species composition. Decreased LAI...