The energy budget of a pumice desert surface was analyzed under
clear skies during early, mid- and late summer periods. The pumice
site is in the semi-arid plateau region of Central Oregon at an elevation
of about 1500 meters. The flat pumice surface is approximately
250 hectares in extent, and...
The High Lava Plains province (HLP) of southeastern Oregon is a Miocene to Recent volcanic upland characterized by widespread basaltic volcanism and west-migrating rhyolitic volcanism. New ⁴⁰Ar/³⁹Ar ages for HLP rhyolites demonstrate that the trend of migrating rhyolitic volcanism is robust, reflecting westward migration at a rate of -35 km/m.y....
A spatially explicit population model written in C++ programming language is used in
this study examining the population dynamics of the Desert Tortoise (Gopherus
agassizii) in the California Mojave Desert. The model is constructed with hexagonal
divisions of space, and with one-year increments of time. Four thematic maps: vegetation,
soil...
The amount and distribution of neutral and adaptive genetic diversity are often assumed to follow similar patterns. However, natural selection on adaptive loci may cause divergence from patterns observed for loci which are only influenced by selectively neutral processes such as genetic drift. The interaction between selection and neutral processes...
This dissertation had three main objectives: 1) investigate the role of macro and micro geomorphology in determining lizard distributions in the Southern California Mojave Desert; 2) develop a spatially explicit lizard habitat model based upon geomorphology; and, 3) determine the interactive effects of geomorphology, roads, and land use in defining...
The Hampton Tuff is a 3.9 ± .02 Ma (2σ) ignimbrite sheet from the High Lava Plains of central Oregon. The majority of known outcrops exist to the north, within ~22 mi (~35 km) of the Frederick Butte Volcanic Center, the proposed source of the tuff. Thickness of the tuff...
Mycorrhizal fungi in arid and semiarid rangelands have received little study in southwest Asia and north Africa, although they are important in food production and rangeland productivity. The desert truffles of the genera Terfezia and Tirmania form fruiting-bodies and mycorrhizae with rangeland plants. This thesis treats the taxonomy and the...