The umbrella species concept is a single-species conservation strategy built on the notion that indirect protections are provided for multiple species that occupy the same area as a single, or umbrella, species. The utility of the umbrella species concept relies on similar associations of abundance, distribution, life history requirements, and...
In the area that is now Saguaro National Park East, grazing began in the 1880's. Because of the impact to the iconic saguaro cactus as well as all palatable plant species in the area, ecological damage in the park were determined to be so great that anti-grazing conservationists challenged the...
Reestablishing native perennial vegetation in annual grass-invaded rangelands is critical to restoring ecosystems, especially following wildfires. Controlling invasive annual grasses is essential to increasing revegetation success; however, pre-emergent herbicides used to control annual grasses prohibit immediate seeding due to non-target herbicide damage. Thus, seeding is often delayed one year following...
Italian ryegrass (Lolium perenne L. spp. multiflorum (Lam.) Husnot) is one of the most troublesome weeds with respect to herbicide resistance selection. Some reasons for this are the numerous documented cases of multiple and cross herbicide resistance and some of the biological characteristics of this species, such as wind cross-pollination...
There is growing interest in using biocrusts (assemblages of cyanobacteria, lichens, mosses, and other taxa in various proportions covering the upper few millimeters of the soil surface) to assist in restoring ecosystem function and native plant communities in dryland ecosystems. Biocrusts can be transplanted and established using jute or thatch,...
Urban landscape water use is increasingly a focus of water conservation efforts. This is especially true in the arid and semi-arid regions of the western United States where increased demand, environmental concerns, and extended periods of drought have created chronic water shortages. However, until recently, little attention has been paid...
Deciduous shrubs are an integral component of mixed conifer forests of the interior Pacific Northwest by providing structural complexity, forage, and niche habitat. Currently, these species are under pressure from high levels of ungulate herbivory and forest management activities such as fuels reduction treatments. Ungulate herbivory is influential in the...
Bioenergy is a rapidly growing subsector of the emerging global bioeconomy, with the potential to create a substantial number of jobs and mitigate climate change. In order to develop bioenergy into a viable industry, capable of providing valuable energy and employment, there is an immediate need for a skilled workforce...
Red clover (Trifolium pratense L.) seed yield can be affected by plant growth regulators (PGR) and irrigation; however, the effects of these factors on physiological maturity (PM), harvest maturity (HM), and seed quality are unknown. The objectives of this study were to: 1) determine how irrigation and trinexapac-ethyl (TE, a...
Natural resource challenges in the American West feature a suite of actors and processes operating at different spatial and political scales, and crossing several administrative jurisdictions. I applied concepts of new environmental governance to Oregon’s greater sage-grouse (Centrocercus urophasianus) conservation strategy, focusing, in particular, on features of voluntary conservation arrangements...