Treesearch

Although the US Department of Agriculture's 2005 public commitment to use market-based incentives for environmental stewardship and cooperative conservation focused land managers' attention on the concept of ecosystem goods and services (EGS), this was not a new idea. Much earlier in the 20th century, Aldo Leopold embraced the value of open space, calling for preservation of New Mexico's Gila Wilderness Area and later urging Americans to espouse a "land ethic" that recognized the unique contributions of wildlands and agricultural landscapes to the American ethos. Theodore Roosevelt...

Although sagebrush, Artemisia spp., does not require an insect pollinator, there are several native species of bumble bees, Bombus spp. (Hymenoptera: Apidae), that are present in sagebrush steppe ecosystems where they act as pollinators for various forbs and shrubs. These native pollinators contribute to plant productivity and reproduction. We captured 12 species of bumble bees (437 individuals) at two sites during this study. The three most commonly captured species of Bombus at the first site (Red Mountain in the Targhee-Caribou National Forest) were B. rufocinctus Cresson, B. fervidus...

Diffusion dominates the transport of trace gases between soil and the atmosphere. Pressure gradients induced by atmospheric flow and wind interacting with topographical features cause a small but persistent bulk flow of air within soil or snow. This forcing, called pressure pumping or wind pumping, leads to a poorly quantified enhancement of gas transport beyond the rate of molecular diffusion. This study was conducted to quantify the role of pressure pumping in enhancement of CO2 transport through a mountain forest seasonal snowpack. Observations of 12CO2 and 13CO2 within the snowpack,...

Soil respiration is a major contributor to atmospheric CO2, but accurate landscape-scale estimates of soil CO2 flux for many ecosystems including shrublands have yet to be established. We began a project to measure, with high spatial and temporal resolution, soil CO2 flux in a stand (11 x 25 m area) of big sagebrush (Artemisia tridentata Nutt.) at the Logan, Utah, Forestry Sciences Laboratory. Beginning on Nov. 1, 2009, hourly soil CO2 flux measurements were made at a single location in the stand using the Li-Cor LI-8100 soil CO2 flux instrument and 20-cm long-term chamber. Beginning in...

Rangelands are areas that are too arid, or with soils too shallow, to support either forests or cultivated agriculture, but that nonetheless produce enough vegetation for livestock grazing. Some arid rangeland regions, notably those with warm, dry climates in temperate zones (e.g., the warm deserts of the United States and adjacent Mexico, parts of Australia, South Africa, California, and around the Mediterranean) host great diversities of native bees, primarily nonsocial species among which are many floral specialists. Conversely, the world's forested lowland tropics support many more...

Low-water landscaping is an essential tool for water conservation in the arid Intermountain West (IMW) for managing limited supplies and population-driven increased demand. The IMW harbors a large number of drought-tolerant native species that have potential for use in the low-water use landscape (LWL). However, many species are not available in the nursery trade due to their morphological confusion and establishment difficulty in the managed landscapes. The overall goal of this study is to elucidate morphological, ecophysiological, and genetic distinctions within two IMW native plant...

Lomatium dissectum (Nutt.) Mathias & Constance is a perennial plant found across much of western North America. For disturbed lands within this range, there is interest in using L. dissectum in restoration. A problem in the propagation of L. dissectum is that at the time of dispersal the seeds are dormant. Thus, prior to usage in restoration projects the type of dormancy and the procedures necessary to release dormancy in these seeds must be determined. Determining the type of dormancy and the treatments necessary to break dormancy in L. dissectum seeds was the primary focus of this study....

Accurate prediction of germination for species used for semi-arid land revegetation would support selection of plant materials for specific climatic conditions and sites. Wet thermal-time models predict germination time by summing progress toward germination subpopulation percentages as a function of temperature across intermittent wet periods or within singular wet periods. Wet periods may be defined by any reasonable seedbed water potential above which seeds are expected to imbibe sufficiently to germinate. These models may be especially applicable to the Artemisia steppe of the western...

The key to stopping high-frequency or catastrophic wildfires in the western U.S.A. is the successful restoration of burned lands to functional plant communities. Developing models of seedling establishment for invasive and native species will help in the selection of species for restoration projects that are able to establish and compete with invasive species given the abiotic conditions of specific sites. Modeling germination is the first step in modeling seedling establishment. We developed thermal germination models and compared predicted and measured germination timing in incubators as...

Theoretical and empirical work has established a positive relationship between resource availability and habitat invasibility. For nonnative invasive annual grasses, similar to other invasive species, invader success has been tied most often to increased nitrogen (N) availability. These observations have led to the logical assumption that managing soils for low N availability will facilitate restoration of invasive plant-dominated systems. Although invasive annual grasses pose a serious threat to a number of perennial-dominated ecosystems worldwide, there has been no quantitative synthesis...