Treesearch

The red-flowered member of Penstemon sect. Chamaeleon from southeastern Arizona and southwestern New Mexico has been treated taxonomically both as part of the Mexican species, P. lanceolatus Benth., and as a separate species, P. ramosus Crosswhite. Under the former treatment the Arizona and New Mexico populations are peripheral populations of a primarily Mexican species; and, under the latter they represent an endemic species restricted to this area. Penstemon ramosus was distinguished from P. lanceolatus by branching below the inflorescence and by having narrow, revolute leaves. Morphologi...

Overgrazing and fire suppression has left much rangeland in poor condition for various wildlife species. Prescribed fire is one range improvement practice used to restore degraded wildlife habitat. I determined the effect of prescribed fire on whitetailed deer (Odocoileus virginianus) spatial and temporal distribution, in the presence of cattle grazing. Three 40 ha patches, constituting 10% and 6% of the land area in the lesser and greater Yellow Bluff pasture, respectively, were burned in September 2005. To determine habitat use and distribution of deer relative to these burns 3 bucks and...

Unusual soils, compared to surrounding common soils, act as edaphic habitat islands and often harbor rare plants. These edaphic elements can be disjuncts or endemics. Two rare wild buckwheats from southeastern Arizona that grow on Tertiary lacustrine lakebed deposits have been found to be a disjunct, and an endemic. Eriogonum apachense from the Bylas area is determined to be a disjunct expression of E. heermannii var. argense, a Mojave Desert taxon from northern Arizona and adjacent California and Nevada, not a distinct endemic species. At a historical location of E. apachense near Vail,...

Federal land managers desire a consistent and cost-effective source of Hedysarum boreale Nutt. seed for rangeland restoration in the Great Basin and adjacent ecosystems. The breeding biology of H. boreale was assessed via hand pollination experiments at 2 sites in Cache County, Utah, USA in 2003. H. boreale was found to be self-compatible, but did not produce fruit and seeds in the absence of bee visitors. Xenogamy (out-crossing) treatments resulted in increased seed viability and decreased predispersal reproductive attrition. H. boreale was found to be homogamous during 2004 experiments...

The Differenced Normalized Burn Ratio (deltaNBR) is widely used to map post-fire effects in North America from multispectral satellite imagery, but has not been rigorously validated across the great diversity in vegetation types. The importance of these maps to fire rehabilitation crews highlights the need for continued assessment of alternative remote sensing approaches. To meet this need, this study presents a first preliminary comparison of immediate post-fire char (black ash) fraction, as measured by linear spectral unmixing, and deltaNBR, with two quantitative one-year post-fire field...

These contributed papers review the current status of plant conservation in the southwestern U.S.

Seed germination is pivotal in the life cycle of native plants in a restorative context because initiation of the metabolic processes critical to establishment is key to survival in such a competitive environment. Dormancy characteristics of some native plants including the subject species, Astragalus utahensis, have evolved mechanisms to control germination in order to maintain a seed bank and ensure germination at the right time under optimal conditions. In vitro germination studies confirm beneficial interactions between Alternaria and Aspergillus fungi and Astragalus utahensis seed....

Snowshoe hare (Lepus americanus) abundance has been of interest to wildlife biologists, as hares are essential prey items for many rare and endangered predators. Snowshoe hare abundance has most commonly been estimated through indices such as pellet counts. While pellet counts may be useful in the areas they are developed and when hares are dense, they notably fail when hares are at low densities. Abundance estimates using capture-mark-recapture (CMR) are often preferred over indices of animal abundance, yet using CMR to estimate snowshoe hare numbers has proven a formidable and expensive...

Delineating a species' geographic range using the spatial distribution of museum specimens or even contemporary detection-non-detection data can be difficult. This is particularly true at the periphery of a species range where species' distributions are often disjunct. Wolverines (Gulo gulo) are wide-ranging mammals with discontinuous and potentially isolated populations at the periphery of their range. One potentially disjunct population occurred in the Sierra Nevada Mountains, California, USA, and appears to have been extirpated by the 1930s. Many early 20th century naturalists believed...

Developing comprehensive conservation strategies requires knowledge of factors influencing population growth and persistence. Although variable prey resources are often associated with fluctuations in raptor demographic parameters, the mechanisms of food limitation are poorly understood, especially for a generalist predator like the northern goshawk (Accipiter gentilis). To determine the reproductive responses of goshawks to variable prey populations, we evaluated 823 goshawk breeding opportunities on the Kaibab Plateau, Arizona, USA, during 1994-2002. Concurrently, density was estimated...