Botanical content of black-tailed jackrabbit diets on semidesert rangeland

Botanical content of black-tailed jackrabbit diets was determined by microhistological examination of fecal samples collected from six different vegetation types in southern New Mexico on three dates. Grasses comprised the largest component of the jackrabbit diets, with dropseed species ( Sporobolus spp.) and black grama ( Bouteloua eriopoda ) the most abundant grasses in the diets. Leatherweed croton ( Croton pottsii ) and silverleaf nightshade ( Solanum elaeagnifolium ) were important forbs on most vegetation types. Diet composition varied in response to season and vegetation type. Grasses were important during the summer growing season, while forbs were selected during their growing season (summer or winter-spring). Shrubs were less abundant in the diet than grasses and forbs.     

Summer food habits of a small mammal community in the pinyon-juniper ecosystem

Summer food habits of a small mammal community in the Piceance Basin of Colorado were investigated during 1977 and 1978 using a combination of fecal and stomach content analyses. Three species, deer mice ( Peromyscus maniculatus ), least chipmunks ( Eutamias minimus ), and plains pocket mice ( Perognathus flavescens ) consumed arthropods as the majority of their diets. Bushy-tailed woodrats ( Neotoma cinerea ) consumed predominantly woody vegetation, and the diet of golden-mantled ground squirrels ( Spermophilus lateralis ) consisted primarily of forbs and fungi. Mountain cottontails ( Sylvilagus nuttalli ) depended heavily on grasses, with a mix of woody vegetation and forbs composing the remainder of their diet. Most of the species investigated selected different foods and thus avoided competition for food. Plains pocket mice may have competed with deer mice for arthropods in 1977.     

Succession in pinyon-juniper woodlands following wildfire in the Great Basin

Twenty - one areas in pinyon ( Pinus monophylla ) - juniper ( Juniperus osteosperma ) woodlands burned by wildfire from approximately 1 to 60 years prior to sampling and adjacent unburned mature woodland stands were studied in Nevada and California to determine successional patterns and individual species responses to burning and to changing plant communities through time. One year after burning, all late successional woodland species were present in postburn plant communities except tree species. Increases in both cover and occurrence of annual and perennial forbs resulted in their dominance on early successional sites. Shrubs and annual grasses dominated midsuccessional sites, subsequently giving way to tree, shrub, and perennial grass dominance in late succession. North and east slopes generally supported high cover and occurrence of shrubs, perennial grasses, and perennial forbs, and south and west slopes generally supported high cover and occurrence of annual forbs and annual grasses. The ability to group species according to preferential occurrence on various aspects and successional stages can be used to predict plant community composition in time and space in the pinyon - juniper woodlands.         

Effects of 2,4-D on a Populus tremuloides community in the western United States-22 years after treatment

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;} Quaking aspen ( Populus tremuloides Michx.) stands were accidentally sprayed with 2,4-D in a sagebrush control program in western Wyoming in 1958. We visited the site during the summer of 1981 to evaluate the long-term effect on the aspen trees and the associated vegetation. Initially, some observers believed that the aspen had been “destroyed.” Subsequent data indicate just the opposite—aspen stocking appeared to have been improved by the treatment. On two of the sampled clones, 22 years after spraying, there were approximately 17,000 more suckers/ha on the sprayed than on the unsprayed plots. These are adequate numbers to restock the site to pretreatment densities. Although undergrowth vegetation appeared to be changed as a result of the treatment, this cannot be attributed solely to the herbicide because heavy grazing, mostly by domestic livestock, has occurred on the grazing allotment. A similarity index was calculated between sprayed and unsprayed portions of the same aspen clones. Forbs were still less on the sprayed areas, whereas grasses were similar on the sprayed and unsprayed areas. Spraying apparently does not have as adverse an effect on aspen communities as some conservationists originally thought.        

Relationship between environmental and vegetational parameters for understory and open-area communities

Ten individuals from each of four tree species were selected, and their associated understory and adjacent open-area communities were sampled for both environmental and vegetational parameters, including light intensity, pH, litter depth, soil depth, and percentages of exposed rock, litter cover, living cover, shrubs, forbs, grasses, and annuals. The four tree species were ponderosa pine, Rocky Mountain juniper, Gambel oak, and snowbrush ceanothus. The study site was in the lower Uinta Mountains about 10 miles east of Kamas, Utah. Correlations among the various biotic and abiotic parameters were examined. The interplay of these factors in differentiating the understory and open-area communities is discussed.       

Tundra vegetation of three cirque basins in the northern San Juan Mountains, Colorado

The vegetation of three alpine cirque basins in the northern San Juan Mountains of southwestern Colorado was inventoried and analyzed for the degree of specificity shown by vascular plant communities for certain types of habitats identified as representative of the basins. A total of 197 vascular plant species representing 31 families was inventoried. Growth forms of all species were noted and a growth form spectrum for all of the communities was derived. The caespitose monocot and erect dicot growth forms are the most important growth forms among the community dominants. The most common growth form among all species is the rosette dicot.           

Ants from northern Arizona and southern Utah

Ants of 22 species were collected in can pit-traps from 16 different vegetative associations to determine distribution, seasonal and annual occurrence, and population as bases for monitoring environmental impact. Thirteen species were sufficiently abundant and distributed to qualify as indicator species. Myrmecocystus mexicanus was the most widespread ecologically. Pogonomyrmex occidentalis was the most abundant species, but second in ecological distribution. The greatest number of species was found in the juniper- Ephedra -grass association, and the fewest species in Ephredra-Coleogyne-Grayia.        

Holocene vegetation and historic grazing impacts at Capitol Reef National Park reconstructed using packrat middens

Mid- to late-Holocene vegetation change from a remote high-desert site was reconstructed using plant macrofossils and pollen from 9 packrat middens ranging from 0 to 5400 yr in age. Presettlement middens consistently contained abundant macrofossils of plant species palatable to large herbivores that are now absent or reduced, such as winterfat ( Ceratoides lanata ) and ricegrass ( Stipa hymenoides ). Macrofossils and pollen of pinyon pine ( Pinus edulis ), sagebrush ( Artemisia spp.), and roundleaf buffaloberry ( Shepherdia rotundifolia ) were recently reduced to their lowest levels for the 5400-yr record. Conversely, species typical of overgrazed range, such as snakeweed ( Gutierrezia sarothrae ), viscid rabbitbrush ( Chrysothamnus visidiflorus ), and Russian thistle ( Salsola sp.), were not recorded prior to the historic introduction of grazing animals. Pollens of Utah juniper ( Juniperus osteosperma ) also increased during the last 200 yr. These records demonstrate that the most sever vegetation changes of the last 5400 yr occurred during the past 200 yr. The nature and timing of these changes suggest that they were primarily caused by the 19th-century open-land sheep and cattle ranching. The reduction of pinyon and sagebrush concurrent with other grazing impacts suggests that effects of cattle grazing at modern stocking levels may be a poor analog for the effects of intense sheep grazing during drought.     

Burrowing Owl foods in Conata Basin, South Dakota

Burrowing Owls ( Athene cunicularia ) were studied in a prairie dog town of southwestern South Dakota. Pellets regurgitated by Burrowing Owls contained a wide variety of prey remains. Insects, spiders, small mammals, and vegetation were the most frequent items identified in the pellets. Mammals were consumed most frequently during spring and early summer. Insects were consumed in large numbers during the entire period of this study, but they became more frequent in owl pellets during late summer and fall in association with a decline of mammal remains. Some prey items observed around owl nest sites were not found in the pellets examined. Possible secondary poisoning of some prey of Burrowing Owls has not produced any change in owl food habits, based on other studies reported in the literature.         

Resource overlap between mountain goats and bighorn sheep

Mountain goat ( Oreamnos americanus ) and bighorn sheep ( Ovis canadensis ) ranges overlap substantially in northwestern United States and southwestern Canada. Resource overlap in food and habitat parameters is assumed, but the degree of overlap has not been estimated. Data from published separate and comparative studies on food and habitat use were used to calculate indices of resource overlap for goats and sheep. Indices of overlap for general forage classes (grasses, forbs, browse) were > 0.90 in summer and winter for data based on pooled data from separate studies and in summer for data for comparative studies. In winter for comparative studies this overlap was 0.64. For studies where forage species were identified, estimates of resource overlap from separate studies were ～ 0.8 but were < 0.5 for comparative studies. Indices of overlap for habitat variables were also low (< 0.7) for comparative studies. It was concluded that possible overlap in food and habitat use by goats and sheep could be extensive; but in sympatric populations resource overlap may be reduced substantially.     

Breeding birds of an ancient bristlecone pine stand in east central Nevada

This paper describes features of the breeding bird population of a Great Basin ancient bristlecone pine stand on Wheeler Peak in White Pine County, east central Nevada. The bird population was determined by spot-mapping methods on a 20-ha plot during June and July 1981. The density of breeding birds was 82 pairs per 40 ha. Fourteen species were territorial. The most abundant species were the Dark-eyed Junco, Mountain Chickadee, Mountain Bluebird, and Townsend&rsquo;s Solitaire. Other common breeding species included the Cassin&rsquo;s Finch, Yellow-rumped Warbler, Pine Siskin, and Dusky Flycatcher. There were 410 individual breeding birds per km 2 . When expressed as standing crop biomass, the Townsend&rsquo;s Solitaire was the predominant species, followed by the Dark-eyed Junco, American Robin, Mountain Bluebird, and Northern Flicker. Total standing crop biomass was 95 g/ha. None of the breeding birds were restricted to the bristlecone pine stand. The structure of the breeding bird community in the bristlecone pine forest compared best to those of the Rocky Mountain and Northern Boreal forest regions.     

Vegetation patterns in relation to slope position in the Castle Cliffs area of southern Utah

Vegetation patterns in relation to slope position were studied on four foothill knolls in the Castle Cliffs area of Washington County, Utah. Study plots were established at four different slope positions: ridge top, upper slope, lower slope, and floodplain. Exposed rock was highest on the ridge top; exposed soil was highest on the floodplain; soil depth increased downslope. Plant life form varied with respect to slope position. Grass, annuals, and cryptogamic crust cover was highest on the ridge top and shrubs were most prominent on the midslope. Forb cover gradually increased downslope. Succulents were restricted to the ridge top or floodplain. Species distribution was distinct and strongly correlated to slope position. Two sets of congeneric species showed strong patterns of niche separation. The vegetation of the slopes is highly distinct at the ridge top and floodplain and grades toward the midslope from both ends. &nbsp;&nbsp;&nbsp;     

Invasion and stabilization of recent beaches by salt grass ( Distichilis spicata ) at Mono Lake, Mono County, California

Invasion of plant species onto recently exposed beaches of Mono Lake, California, was documented. Three vegetation zones were evident on these beaches. The first was formed entirely of annual species. The second was composed of annuals mixed with salt grass, and the third was formed entirely of salt grass. Stabilization of these beaches was accomplished by the aggressive growth of salt grass rhizomes. &nbsp;&nbsp;&nbsp;     

Comparisons of prescribed burning and cutting of Utah Marsh plants

The efficacy of cutting (haying) versus burning was compared for control of marsh vegetation in Utah. Cutting reduced production of hardstem bulrush ( Scirpus lacustris ), alkali bulrush ( S. maritimus ), and cattail ( Typha spp.) compared to levels found on burned plots, but differences were significant (P Distichlis spicata ) plots greatly reduced production upon reflooding, which produced results similar to prescribed burning and reflooding. Heat penetration into the sediments during the fire was not sufficient to cause substantial belowground mortality. Without belowground mortality, prescribed burning alone did not change aboveground production or species composition. Flooding after fire did eliminate saltgrass, but a single prescribed burning or cutting was not an effective management tool for reducing production of cattail, hardstem bulrush, and alkali bulrush. &nbsp;&nbsp;&nbsp;     

Soil water and temperature response to prescribed burning

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;} Prescribed burning of Texas wintergrass ( Stipa leucotricha Trin. & Rupr.) communities reduced soil water contents for two to six months, and additional reductions occurred when the subsequent crop of cool-season grasses and forbs began growth. These soil water reductions occurred despite reduced plant production following burning. Soil water reductions were greater at 15 to 45 cm depths than in the upper 15 cm and greater following spring burning. Soil temperatures were higher on burned plots for most of the first year following burning. &nbsp;&nbsp;     

A new combination and a new variety in Artemisia tridentata

The combination Artemisia tridentata Nutt. ssp. spiciformis (Osterhout) Goodrich & McArthur comb. nov. is made. This high elevation taxon was originally described at the species level and more recently has generally been treated as a form of A. tridentata ssp. vaseyana . The subspecies designation is supported by its parallel nature to the other A. tridentata&nbsp; subspecies and by its relatively widespread and locally abundant populations. Also, a new variety of A. tridentata ssp. vaseyana is proposed. &nbsp;&nbsp;&nbsp;     

Allelopathic effects of bur buttercup tissue on germination and growth of various grasses and forbs in vitro and in soil

The allelopathic effects of bur buttercup ( Ranunculus testiculatus ) tissue on selected grasses and forbs varied according to the substratum for germination and growth. The in vitro effects of an aqueous extract of buttercup tissue on germination and root development of five grasses were strongly inhibitory in all cases. &nbsp; However, in soil the effects of buttercup tissue on germination and growth of seven grasses and two dicotyledonous herbs were small to nonsignificant. Deleterious effects were less severe in fine - as opposed to coarse-textured soils. Under field conditions, the ability of seedlings of the grasses to compete with buttercup varied with the species.     

Distribution and abundance of birds in the White Mountains, California

This paper quantifies the distribution and abundance of birds in the White Mountains, Inyo and Mono counties, California, during spring-summer 1989-91, to establish a baseline for monitoring the area's avifauna. Overall 58 species were encountered in the single-leaf pinyon-Utah juniper ( Pinus monophylla-Juniperus osteosperma ) zone, and 61 species in the bristlecone-limber pine ( P. longaeva-P. flexilis ) zone. The bristlecone-limber pine zone had a significantly greater overall bird abundance relative to the pinyon-juniper. Both zones were characterized by few very abundant species, a few moderately abundant species, and numerous rare species. The Black-throated Gray Warbler (scientific names in tables), Gray Flycatcher, and Pinyon Jay were the most abundant species in the pinyon-juniper whereas the Clark's Nutcracker, Mountain Chickadee, and Cassin's Finch were the most abundant species in the bristlecone-limber pine. There were few ecological or taxonomic replacements of species between zones, with the differences in distribution and abundance related primarily to the interaction between elevation and vegetation. Significant inter-year variation in abundance was found for about 20 species in each zone—more species showed declining rather than increasing trends. The Mountain Chickadee and White-breasted Nuthatch declined, whereas the Gray Flycatcher and Rock Wren increased across years in both zones. Reasons for declines in some species might be the severe drought that continued throughout this study.     

Pollinators of Astragalus monoensis Barneby (Fabaceae): new host records; potential impact of sheep grazing

Important bee species inhabiting the study area are listed, including those observed and collected foraging on Astragalus monoensis , a California rare plant. The significance of each species as a potential pollinator is assessed, based on frequency of occurrence in collecting, observed and published host plant records, and morphology. Three pollinator categories are proposed: observed and/or collected on the plant, probable visitors, and possible visitors. New host plant records for these species are listed. Current sheep grazing practices in the A. monoensis habitat endanger pollinators in four ways: (1) destruction of potential nest sites, (2) destruction of existing nests and contents, (3) direct trampling of adult bees, and (4) removal of food resources. Exposure of the major bee species to each of these factors is assessed utilizing experimental data and published information. &nbsp;&nbsp;&nbsp;     

Late quaternary plant zonation and climate in southeastern Utah

Plant macrofossils from packrat middens in two southeastern Utah caves outline development of modern plant zonation from the late Wisconsin. Allen Canyon Cave (2195 m) and Fishmouth Cave (1585 m) are located along a continuous gradient of outcropping Navajo Sandstone that extends from the Abajo Mountains south to the San Juan River. By holding the site constant, changes in the floral composition for a plot of less than one hectare can be observed, even if sporadically, over tens of millennia. At Allen Canyon Cave, Engelmann spruce-alpine fir forest was replaced by the present vegetation consisting of pinyon-juniper woodland on exposed ridgetops and cliffside stands of Douglas fir, ponderosa pine, and aspen. Xerophytic woodland plants such as pinyon, plains prickly pear, and narrowleaf yucca arrived sometime in the middle Holocene between 7200 and 3400 B.P. At Fishmouth Cave, Utah juniper in Holocene middens replaced blue spruce, limber pine, Douglas fir, and dwarf and Rocky Mountain junipers in late Wisconsin samples. Disharmonious associations for the late Wisconsin occur only at the lower site with the xerophytes Mormon tea, plains prickly pear, and narrowleaf yucca growing alongside subalpine conifers. One possible explanation involves the late Wisconsin absence of ponderosa and pinyon pines from the Colorado Plateaus. Released from competition at their lower limits, subalpine conifers were able to expand into lower elevations and mix with xerophytic plants found today in understories of pinyon-juniper and ponderosa pine woodlands. Quantitative climatic estimates are derived for the late Wisconsin by applying vertical gradients for temperature and precipitation to the amount of vegetation depression. The Fishmouth Cave sequence indicates a minimum lowering of 850 m for blue spruce, limber pine, and dwarf juniper. A depression of at least 700 m for Engelmann spruce and alpine fir is suggested for the Allen Canyon locality. Use of conservatively low gradients for stations below 2080 m yields a 3&ndash;4 C cooling from present mean annual temperature and 35 to 60 percent more rainfall than today. Steeper gradients associated with more mountainous terrain suggest a 5 C lowering in temperature and up to 120 percent increase over modern precipitation. &nbsp;&nbsp;