Treesearch

Biological control of pest Bruchidae may provide an important management strategy against infestation of stored grain legumes, a key source of dietary protein in developing countwies. Previous related research has focused on the potential of parasitoids to contwol bruchids; the role of generalist predators in this application has not yet been extensively explored.

This study examined the variations in the chemical parameters of soils of seven forests located along a historical deposition gradient spanning 8.5° longitude from southern Illinois to central West Virginia. Four to six mature control plots were sampled on two of the sites, and two experimentally thinned and two control plots were sampled on the remaining five sites. Most soil properties varied significantly both among experimental forests and between control and thinned plots. Soil pH, Al, PO 4 and inorganic N were correlated with longitude, whereas differences in Ca, Mg and Ca:A1 ratio...

On 20 September 1995 at 11:15 MST, during routine mist-netting for a study investigating the use of the middle Rio Grande riparian habitat by migratory land birds at Rio Grande Nature Center, Bernalillo County, New Mexico, we were surprised to discover a light yellowish warbler in one of the nets. After careful examination and comparison, the bird was identified as a hatching-year (by incomplete skull ossification) Wilson's Warbler with albino plumage. The sex was not determined.

We studied timing, abundance, subspecies composition, fat stores, stopover length, and habitat use of Willow Flycatchers (Empidonax traillii) during spring and fall stopover along the Middle Rio Grande, New Mexico. Spring migration started in mid-May and lasted about a month. Fall migration started in early-August and also lasted about a month. The most abundant subspecies was the Southwestern Willow Flycatcher (E. t. extimus), followed by E. t. brewsteri, E. t. adastus, and E. t. traillii. Nearly half of the Willow Flycatchers captured had no observable fat. Spring flycatchers had more...

Using standardized mist-netting capture data from the Rio Grande Nature Center, Albuquerque, New Mexico from 1985-1994, and Breeding Bird Survey data from New Mexico and United States from 1980-1994, we compared local, regional, and national population trends of landbird species that migrate along the middle Rio Grande in fall. Evaluations of relationships among population trends, migratory distance, breeding habitat use, nest type, and foraging guilds revealed that population trends of Rio Grande migrants were relatively species-specific and that population changes were unequally distribut...

Vegetation of the alpine zone of eight mountain ranges in southwestern Montana was classified using IWINSPAN, DECORAN, and STRATA-algorithms embedded within the U.S. Forest Service Northern Region's ECADS (ecological classification and description system) program. Quantitative estimates of vegetation and soil attributes were sampled from 138 plots. Vegetation composition, structure, productivity, associated soil features, and landscape positions are described for the 23 recognized community types that include wetland, snowbed, cushion plant, turf, and grassland physiognomic types. Field...

Andisols support ≈ 200 000 ha of mid-elevation grand fir (Abies grandis [Dougl. ex D.Don] Lindl.) forests in the Pacific Northwest region that are characterized by little or no natural conifer regeneration following removal of the forest canopy. Previous work suggests that the properties of these Andisols have been altered as a result of the establishment of successional communities dominated by bracken fern (Pteridium aquilinum [L.] Kuhn) in deforested areas. In this study, we compared soil properties in a 30-yr-old bracken fern site (clear-cut in 1965), a natural bracken fern site that...

The Butte City Fire occurred on July 1, 1994, west of Idaho Falls, ID. Ignited from a burning flat tire, the blaze was driven by high winds that caused it to cover over 20,500 acres in just over 6.5 hours. Sagebrush (Artemisia tridentata ssp. wyomingensis) is the principal shrub species of this high desert rangeland. With the absence of vegetation after the fire, erosion increased tremendously. Because the fire occurred on the Idaho National Engineering Laboratory, researchers were able to gather weather information from remote meteorological stations positioned on and around the site.

Tree based statistical models can be used to investigate data structure and predict future observations. We used nonparametric and nonlinear models to reexamine the data sets on tree growth used by Bechtold et al. (1991) and Ruark et al. (1991). The growth data were collected by Forest Inventory and Analysis (FIA) teams from 1962 to 1972 (4th cycle) and 1972 to 1982 (5th cycle). We used tree based models to group observations into clusters that were specified by covariate values. Next, we performed a permutation test on the grouped data to test for a change in tree growth rates from the...

Vegetation at the Glacier Lakes Ecosystem Experiment Site, a 600 ha research site at 3200 to 3500 m elevation in the Snowy Range of southeastern Wyoming, was categorized and described from an intensive sampling of species abundances. A total of 304 vascular plant taxa were identified through collection and herbarium documentation. Plots with tree species were separated from those without tree species for ordination and classification analyses. Detrended correspondence analysis was used to order plots along major axes of composition variation, which are inferred moisture and topographic...