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Many of the issues archaeologists are confronted with are similar to those encountered by natural resource biologists including increased urbanization and industrialization. We investigated bat use of archaeological structures at Montezuma Castle (i.e., Montezuma Castle Unit and Montezuma Well Unit), Tonto, and Tuzigoot National Monuments, Arizona to determine the impact of bats on archaeological structures. Archaeological sites were checked for bats or bat sign (i.e., guano or urine stains) and recommendations were made regarding bat use of the archaeological sites at each of the monuments. Guano was found in all the archaeological sites checked at Montezuma Castle National Monument. We found ≤3 individuals of two species day roosting, and approximately 40 individuals of seven species night roosting in the five-story cliff dwelling at Montezuma Castle Unit. A maternity colony of Townsend's big-eared bats (Corynorhinus townsendii) was roosting in Swallet Cave at Montezuma Well Unit. Bats used the crevices in the rock face above the cliff dwellings for roosting at Tonto National Monument. We found small amounts of guano in the tower room of the pueblo at Tuzigoot National Monument. Bats were not causing damage to the archaeological structures.
The quantity of exudation and the viscosity of pine oleoresins are thought to influence the performance of herbivores and pathogens, but little is known about how fire events affect oleoresin properties. We tested two hypotheses regarding resin properties following a fire event: (1) exudation quantity and viscosity of resins differ between trees in burned and unburned stands, and (2) in burned stands variation in resin exudation quantity and viscosity are predictable by individual tree characteristics. We quantified constitutive resins in burned and unburned stands four months post-fire and determined mean resin exudation quantities and viscosity in a southwestern ponderosa pine (Pinus ponderosa) ecosystem. Mean resin exudation quantities were 35% higher in burned stands than unburned stands (24.267 g and 18.057 g, respectively), and mean viscosity was 22% lower in trees in burned stands than unburned stands (52.24 and 66.14 poises, respectively). In burned areas, resin exudation and resin viscosity were weakly predicted by several individual tree characteristics. Tree diameter and percentage of live crown were positively correlated with the quantity of resin exudation, but basal area was negatively correlated with exudation quantity. The percentage of live crown was the only variable related to resin viscosity. This study shows that ponderosa pine resin properties are affected by fire events, and that some individual tree characteristics may predict the expression of resin defenses in burned stands.
This note describes the addition of 64 native and 8 exotic species to the known vascular flora of the Appleton-Whittell Research Ranch. Many of the additional species were found in unique riparian areas or during detailed plot inventories and are considered rare or uncommon in their abundance.
Although it is a rare phenomenon, hail on the Colorado Plateau can be a significant hazard. This study identifies threshold values of specific atmospheric variables associated with observed severe hail occurrences for northern Arizona during the North American monsoon seasons associated with the 1996–2009 timeframe. The threshold constraints on hail are found by constructing long-term means of the overall, non-severe hail, and severe hail atmospheric environments over northern Arizona, based on Flagstaff, Arizona, 1200 UTC radiosonde data. Results indicate that days experiencing severe hail possess a significantly different morning atmospheric profile. Key variations between days with severe hail versus days without severe hail are elevated sub-300-hPa moisture, a warmer atmosphere, lighter above surface wind speeds, more southerly to southeasterly oriented winds throughout the atmospheric column (except at the 700-hPa pressure level), and noticeably higher geopotential heights at all mandatory pressure levels. Large-scale synoptic patterns associated with the North American Monsoon are the driving force behind whether a severe hail or non-severe hail environment exists over northern Arizona.
Urban and regional temperature trends in southern Nevada, including the rapidly growing Las Vegas metropolitan area, were analyzed over two periods, 1940–2009 and 1977–2009. The data show that minimum temperatures in Las Vegas increased by more than 4°C above the regional trend since 1940 and by approximately 3°C more than the regional average since 1977, which demonstrates that urbanization has significantly altered the nighttime climate of the city and that the changes were most pronounced in the last 30 years. In contrast, regional minimum temperature increases were not widespread and generally limited to spring and summer with a regional annual average minimum temperature increase of about 1°C since 1940 and 0.6°C since 1977. Notably, there is little evidence of winter temperature moderation throughout rural southern Nevada in either time period investigated. The analysis also suggests maximum temperature trends in Las Vegas have been moderated by urbanization, as daytime temperatures across southern Nevada increased by approximately 1°C in the last 30 years, but no increase was observed within the city suggesting that Las Vegas has developed a moderate daytime urban cool island. While no absolute change in Las Vegas dewpoint temperatures was found, a relative increase of up to 3°C was observed when the city was compared to a rural control station. The relative increase in urban dewpoint temperature is significantly correlated to the daytime urban cooling trend, minimum temperature increase, and the significant reduction in diurnal temperature range, suggesting that increased latent heat flux in Las Vegas may be a primary cause of observed urban climate changes.
Douglas-fir dwarf mistletoe (Arceuthobium douglasii) is a parasitic flowering plant that infects Douglas-fir (Pseudotsuga menziesii) throughout the western United States. Douglas-fir dwarf mistletoe induces the formation of witches' brooms which alters infected host branch biomass and architecture. Little work has quantified the effects of this parasite on branch morphology and biomass. This study obtained pairs of broomed and non-broomed Douglas-fir branches for estimating and comparing the biomass of each branch type. Branch pairs meeting 9 specific criteria were randomly selected from a pool of broomed and non-broomed branches from three mixed conifer study sites on the San Francisco Peaks, Arizona severely infested with Douglas-fir dwarf mistletoe. A total of 17 branch pairs were sampled. Branch pairs were carefully collected, dissected into smaller segments based on branch and twig diameter classes, needles, and loose debris. Branch material was then dried and weighed to determine total biomass and the biomass of specific branch components. Overall, broomed branches had approximately two times the biomass of non-broomed branches. Differences in biomass between broomed and non-broomed branches ranged from as low as 400 g to as high as 1200 g. The greatest increases in biomass between broomed and non-broomed branches were for needles and twigs > 25 mm in diameter. Because of the much greater biomass found in witches' brooms caused by Douglas-fir dwarf mistletoe, particularly needle biomass, brooms provide a structurally diverse habitat for a variety of wildlife species which use brooms for resting, hiding, foraging, and nesting sites.
We present new data describing relict periglacial landforms preserved in the interior Great Basin of the southwestern United States. This summary is significant because a thorough understanding of the occurrence and spatial distribution of these landforms is still lacking after 60 years of geomorphic studies in this region. This is largely because many landforms are often un-recognized and because many mountains in the Great Basin are remote and offer poor access. To help address this knowledge gap, we use a GIS with high-resolution imagery and field mapping to identify and describe features that indicate a locally extensive periglacial environment existed in the Snake Range of east-central Nevada during the Late Quaternary. We also compare the location of these landforms with solar radiation models produced using ESRI's Solar Analyst to evaluate the efficacy of using solar modeling as means to predict suitable field sites for periglacial landforms. This simple modeling technique accurately identifies the location of known periglacial landforms in the Snake Range and therefore we believe it could be used to prioritize sites of interest throughout the Great Basin.