Medusahead (Taeniatherum caput-medusae ssp. asperum (Simk.) Melderis) is a Eurasian annual grass that infests large areas of U.S. rangelands, dominating former bunchgrass/shrub sites. Squirreltail (Elymus elymoides (Raf.) Swezey) is a native perennial grass that has demonstrated the ability to establish in stands of medusahead.
A study conducted on two sites...
Numbers of wild Canada geese (Branta canadensis) have increased dramatically during the past 30 years in the lower Columbia and Willamette Valley systems. The damage they cause by grazing and trampling plants can be substantial.
The objectives of this research were to:
1) Develop methods that provide reliable estimates of...
A greater than 10-fold increase in Canada goose (Branta canadensis) populations over the past several years has resulted in concerns over grazing impacts on grass seed production in the mid-Willamette Valley, Oregon. This study was designed to develop methods to quantify and statistically analyze goose-grazing impacts on seed yields of...
The goal of this dissertation is to examine the effectiveness of high intensity-short duration goat browsing for the control of Himalayan blackberry (Rubus armeniacus) and English ivy (Hedera helix), two widespread noxious weeds in the Pacific Northwest.
The effects of goat browsing on Himalayan blackberry vigor, as quantified by densities...
Invasion by non-native plants into natural areas is an important component of global change that threatens biodiversity and ecosystem structure and function. Mountains are currently among the least invaded ecosystems, however, these biodiversity hotspots are increasingly under threat of exotic plant invasion. Evaluation of plant species distribution patterns in mountain...
A case study examining the relationship between stream temperatures and the thermal environment through which streams flow was conducted on the headwaters of 4 tributaries of the Burnt River (Barney, Elk, Greenhorn, and Stevens Creeks) in northeastern Oregon during July through August 1998 and 1999. Barney Creek and Stevens Creek...
Biological plant invasions are diminishing the ecological integrity and function of ecosystems worldwide. A primary example of this is in the Great Basin of the United States, where invasive annual grasses, like cheatgrass (Bromus tectorum L.) and medusahead (Taeniatherum caput-medusae L. Nevski), are dominating many sagebrush-steppe ecosystems. In these invaded...
Two tributaries of the south fork of the Burnt River, near Unity Oregon were studied
during the summers of 2000 and 2001 to determine water heating and cooling
patterns. Hourly temperature data were recorded for air, water, and soil parameters
at four elevations 150m apart on Barney and Stevens Creeks....
Crested wheatgrass (Agropyron cristatum (L.) Gaertn.) is a nonindigenous perennial grass that was introduced to North America to improve the condition of degraded rangelands. It has proven to be a successful revegetation species due to its superior ease of establishment, strong competitive ability, and ability to tolerate grazing. However, crested...