Geology topics

G.W. Miller

Publications and source records attributed to G.W. Miller.

3 recordsLinked to original sources

USGS2011

Predicting breeding bird occurrence by stand- and microhabitat-scale features in even-aged stands in the Central Appalachians

Spatial scale is an important consideration when managing forest wildlife habitat, and models can be used to improve our understanding of these habitats at relevant scales. Our objectives were to determine whether stand- or microhabitat-scale variables better predicted bird metrics (diversity, species presence, and abundance) and to examine breeding bird response to clearcut size and age in a highly forested landscape. In 2004–2007, vegetation data were collected from 62 even-aged stands that were 3.6–34.6 ha in size and harvested in 1963–1990 on the Monongahela National Forest, WV, USA. In 2005–2007, we also surveyed birds at vegetation plots. We used classification and regression trees to model breeding bird habitat use with a suite of stand and microhabitat variables. Among stand variables, elevation, stand age, and stand size were most commonly retained as important variables in guild and species models. Among microhabitat variables, medium-sized tree density and tree species diversity most commonly predicted bird presence or abundance. Early successional and generalist bird presence, abundance, and diversity were better predicted by microhabitat variables than stand variables. Thus, more intensive field sampling may be required to predict habitat use for these species, and management may be needed at a finer scale. Conversely, stand-level variables had greater utility in predicting late-successional species occurrence and abundance; thus management decisions and modeling at this scale may be suitable in areas with a uniform landscape, such as our study area. Our study suggests that late-successional breeding bird diversity can be maximized long-term by including harvests >10 ha in size into our study area and by increasing tree diversity. Some harvesting will need to be incorporated regularly, because after 15 years, the study stands did not provide habitat for most early successional breeding specialists.

Forest Ecology and Management↗

USGS1987

Populations of trap-nesting wasps near a major source of fluoride emissions in western Tennessee

Trap-nesting wasps were collected from eight sites at distances of from 1.2-33.0 km from an aluminum reduction plant in western Tennessee. The sites had similar topographies, soils, and vegetation, but differed in their exposure to fluoride, which was emitted in large quantities from the plant. It was postulated that if fluoride emissions had greatly changed the insect community then relative densities of their predators would have varied accordingly. However, the degree of fluoride pollution was unrelated to the relative densities of the wasps and to the number of cells provisioned with prey. Monobia quadridens, Trypargilum clavatum, and T. lactitarse were found to have two complete generations in western Tennessee. Trypargilum collinum rubrocinctum has at least two generations, and Euodynerus megaera probably has three generations. Six other wasp species and a megachilid bee were also collected.

Proceedings of the Entomological Society of Washin↗

USGS1984

Contamination of the O2 soil horizon by zinc smelting and its effect on woodlouse survival

Samples of litter from the O2 horizon of Dekalb soil (loamy-skeletal, mixed, mesic Typic Dystrochrept) were collected from 18 ridgetop sites on a transect that ran by two Zn smelters in Palmerton, Pa. Metal concentrations increased by regular gradations from a minimum at a site 105 km west of the smelters (67 mg/kg Zn, 0.85 mg/kg Cd, 150 mg/kg Pb, 11 mg/kg Cu) to a maximum 1.2 km east of the smelters (35 000 mg/kg Zn, 1300 mg/kg Cd, 3200 mg/kg Pb, 280 mg/kg Cu), and then decreased until they reached an eastern minimum at the easternmost site, 19 km from the smelters. An increase in the P concentrations near the smelters showed that the emissions were disrupting nutrient flow through the ecosystem. An increase in the pH near the smelters was attributed to the high concentrations of Zn. The log of the distance of the sites from the smelters was significantly correlated ( r = −0.80, p < 0.05) with the mortality of woodlice ( Porcellio scaber Latreille) fed samples of the litter during an 8-week test. There was substantial mortality of woodlice observed even in the O2 litter collected 19 km east of the smelters. Zinc, cadmium, lead, copper, and sulfur were experimentally added, alone or in combination, to O2 litter collected far from any known source of metal emissions. The highest concentration of Zn added (20 000 mg/kg) was toxic enough to account for the mortality observed in the earlier test. A lower concentration of Zn (5000 mg/kg) as well as the concentration of Cd (500 mg/kg) tested also significantly ( p < 0.05) increased the mortality of woodlice.

Journal of Environmental Quality↗