Functional characteristics of wilderness streams twenty years following wildfire

We compared functional attributes of streams draining catchments burned by wildfire 20 years previously to those of streams in unburned catchments. Long-term analyses of channel profiles indicated most channel change occurred within the first 10 years after fire with little subsequent change the following 10 years. Much of the standing dead timber had fallen, and its effect on stream morphology was directly related to stream size, with important ramifications for future years as decay progresses. The volume of wood in the active channel was 5X higher in a 3rdorder burn stream than in other burn or reference streams, but > 80% of this wood was still bridging the stream. Retention of leaves was strongly associated with channel morphology and location of debris dams. Sediment respiration was significantly greater (1.7X) in streams of burned catchments, resulting from greater amounts of loosely attached organic matter in the sediments of these streams. In concordance with respiration results, coefficients of exchange (k ex ) were almost 5X higher in burn streams than in reference streams, although estimates of transient storage were similar between stream types. We expect the input of large woody debris to increase in the next 10 years in fire-impacted streams as bridging trees collapse into the stream, thereby enhancing channel complexity and habitat heterogeneity, instream metabolism and retention, and consequently stream function. The results emphasize the importance of landscape history, such as large-scale wildfires, on present patterns and processes in stream ecosystems.     

Size, structure, and habitat characteristics of populations of Braya humilis var. humilis (Brassicaceae): an alpine disjunct from Colorado

Size, structure, and habitat characteristics were studied in three populations of Braya humilis var. humilis (C. A. Meyer) Robins, in Gray & Wats. (Brassicaceae), a small, herbaceous perennial of the alpine tundra in central Colorado. There was a significant association between numbers of reproductive, juvenile, and seedling individuals and population location. Plant size within reproductive, juvenile, and seedling size classes varied significantly among three populations. Plots containing Braya had significantly lower total plant cover, a different set of dominant plant species, more rock, bare ground, and less litter than plots without Braya . Braya appears to be restricted to calcareous substrates that experience a moderate level of disturbance, such as solifluction lobes and abandoned roads. Populations are small despite the existence of much potential habitat. Population studies are necessary for active conservation management of Braya .     

Gray Partridge foraging ecology in eastern South Dakota

We examined crop contents of 217 Gray Partridge ( Perdix perdix ) collected during a two-year period in eastern South Dakota. Row crop grains (corn, sunflowers) dominated late fall, winter, and spring diets. Small grains (oats, barley, wheat, rye) were rarely consumed although fields of small grains were widely available. During a severe winter when waste row crop grains were buried by snow, partridge consumed more leafy vegetation. Insects dominated the early summer diet, while foxtail ( Setaria spp.) seeds were a major late summer and early fall food.     

Biomass of fifty conifer forests and nutrient exports associated with their harvest

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Biomasses of climax Rocky Mountain forests studied ranged from less than 50 to more than 300 tons/ha. Total biomass was approximately 1.5 times the biomass of normally merchantable boles. When compared with conventional bole harvest, the nutrient exports associated with harvest of all aboveground parts in these stands would apparently be at least three times higher for nitrogen, six times higher for phosphorus, four times higher for potassium, and three times higher for calcium.        

Plant and soil relationships in two hydrothermally altered areas of the Breat Basin

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} In two areas of hydrothermally altered rocks in the Great Basin, the native vegetation differs in composition and areal cover from unaltered to altered sites on the same geologic formations. Analysis suggests that physical rather than chemical factors may be the cause of the vegetation differences, especially permeability of bedrock, depth and texture of soils, and, possibly, amounts and types of clay minerals present. These characteristics influence the ability of soils to absorb and retain water. In the East Tintic Mountains, Utah, the soils from argillized or mixed argillized and silicified parent materials have more characteristics associated with dryness and support sparser vegetation and more species especially adapted to dry conditions than do soils from unaltered or silicified parent materials. In Battle Mountain, Nevada, unaltered areas have greater vegetation cover and have soil depth and texture that are more favorable for plants than do altered areas. Soil pH is higher in altered areas than in unaltered areas.     

Influence of precipitation and temperature on ring, annual branch increment, and needle growth of White Fir and Douglas-fir in central Utah

The study evaluates growth variations in mixed stands of Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) and White Fir ( Abies concolor Hoopes) from the Bighorn Ranch in northern Sanpete County, Utah. The study area lies 26 km southwest of Thistle, Utah. Tree-ring width, annual branch growth and needle length for the period 1970–1976 were obtained from Douglas-Fir and White Fir individuals distributed along an altitudinal and moisture gradient. Elevation ranged from 2257 m to 2500 m above sea level. Temperature and precipitation are shown to exert a significant influence on needle and annual branch growth and width of the annual rings. It was found that multiple correlation coefficients were always larger than the simple correlation coefficients. This suggests that the trees are responding to both temperature and precipitation. Annual branch growth is shown to be positively correlated with ring width and needle length. The influence of precipitation on growth is synchronized with 1 October–1 June precipitation. Best growth occurs in cool, moist years and at lower elevations.     

Factors affecting selection of winter food and roosting resources by porcupines in Utah

Ecological and phytochemical factors potentially affecting winter dietary discrimination by porcupines ( Erethizon dorsatum ) in the mountain brush zone of Utah were studied. Porcupines utilized gambel oak ( Quercus gambelii ) as their primary winter food and roosting resource. Big-tooth maple ( Acer grandidentatum ) was the most common tree species in the study area but was rarely utilized by porcupines. Conifer species were used as a food and roosting resource significantly less often than they occurred in the study area, despite thermal advantages provided by their relatively dense canopies. Oak feed trees were successfully separated from conifer feed trees by discriminant analysis 100% of the time. Oak trees were correctly classified as feed and nonfeed trees 71% of the time. Gambel oak contained higher amounts of crude protein, fiber, and tannins, but was lower in either extract fractions and fatty acid content than conifers. A layer of adipose tissue used as an energy reserve by porcupines may have relaxed energy intake demands sufficiently to permit them to concentrate on a diet of oak tissue, which is high in protein, rather than a high-fat conifer diet. A diet relatively high in protein may have facilitated digestion of food material high in fiber. Temperature did not affect selection of tree species for roosting. Rock and snow caves were utilized infrequently and the study population ranged widely. Three of 15 study animals were eaten by predators.     

Colony isolation and isozyme variability of the western seep fritillary, Speyeria nokomis apacheana (Nymphalidae), in the western Great Basin

Thirteen Speyeria nokomis apacheana (Edwards) (Nymphalidae) populations from the western Great Basin were assayed for isozyme variability using starch-gel electrophoresis. Eight of the 25 presumptive isozyme loci analyzed were found to be polymorphic. Collections made in 1991and 1992 allowed for between-year comparisons of heterozygosity and the estimation of effective population size for five of the sampled populations. Speyeria nokomis apacheana populations exhibit lower mean heterozygosity levels than other nymphalids. This may be attributed to genetic drift in apparently isolated populations with small effective sizes.     

Comparison of two roadside survey procedures for dwarf mistletoes on the Sawtooth National Forest, Idaho

Two roadside surveys were conducted for dwarf mistletoes parasitizing lodgepole pine and Douglas-fir on the Sawtooth National Forest, Idaho. One survey used variable-radius plots located less than 150 m from roads. The 2nd survey used variable-radius plots established at 200-m intervals along 1600-m transects run perpendicular to the same roads. Estimates of the incidence (percentage of trees infected and percentage of plots infested) and severity (average dwarf mistletoe rating) for both lodgepole pine and Douglas-fir dwarf mistletoes were not significantly different for the 2 survey methods. These findings are further evidence that roadside-plot surveys and transect-plot surveys conducted away from roads provide similar estimates of the incidence of dwarf mistletoes for large forested areas.