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Invasive potential of cattle fever ticks in the southern United States.
Get PDFFor >100 years cattle production in the southern United States has been threatened by cattle fever. It is caused by an invasive parasite-vector complex that includes the protozoan hemoparasites Babesia bovis and B. bigemina, which are transmitted among domestic cattle via Rhipicephalus tick vectors of the subgenus Boophilus. In 1906 an eradication effort was started and by 1943 Boophilus ticks had been confined to a narrow tick eradication quarantine area (TEQA) along the Texas-Mexico border. However, a dramatic increase in tick infestations in areas outside the TEQA over the last decade suggests these tick vectors may be poised to re-invade the southern United States. We investigated historical and potential future distributions of climatic habitats of cattle fever ticks to assess the potential for a range expansion. We built robust spatial predictions of habitat suitability for the vector species Rhipicephalus (Boophilus) microplus and R. (B.) annulatus across the southern United States for three time periods: 1906, present day (2012), and 2050. We used analysis of molecular variance (AMOVA) to identify persistent tick occurrences and analysis of bias in the climate proximate to these occurrences to identify key environmental parameters associated with the ecology of both species. We then used ecological niche modeling algorithms GARP and Maxent to construct models that related known occurrences of ticks in the TEQA during 2001-2011 with geospatial data layers that summarized important climate parameters at all three time periods. We identified persistent tick infestations and specific climate parameters that appear to be drivers of ecological niches of the two tick species. Spatial models projected onto climate data representative of climate in 1906 reproduced historical pre-eradication tick distributions. Present-day predictions, although constrained to areas near the TEQA, extrapolated well onto climate projections for 2050. Our models indicate the potential for range expansion of climate suitable for survival of R. microplus and R. annulatus in the southern United States by mid-century, which increases the risk of reintroduction of these ticks and cattle tick fever into major cattle producing areas
2013 Wildfire Season: An Overview, Southwestern U.S.
Get PDFEcological restoration is a practice that seeks to heal degraded ecosystems by reestablishing native species, structural characteristics, and ecological processes. The Society for Ecological Restoration International defines ecological restoration as "an intentional activity that initiates or accelerates the recovery of an ecosystem with respect to its health, integrity and sustainability...Restoration attempts to return an ecosystem to its historic trajectory" (Society for Ecological Restoration International Science & Policy Working Group 2004). Most frequent-fire forests throughout the Intermountain West have been degraded during the last 150 years. Many of these forests are now dominated by unnaturally dense thickets of small trees, and lack their once diverse understory of grasses, sedges, and forbs. Forests in this condition are highly susceptible to damaging, stand-replacing fires and increased insect and disease epidemics. Restoration of these forests centers on reintroducing frequent, low-severity surface fires--often after thinning dense stands--and reestablishing productive understory plant communities. The Ecological Restoration Institute at Northern Arizona University is a pioneer in researching, implementing, and monitoring ecological restoration of frequent-fire forests of the Intermountain West. By allowing natural processes, such as low-severity fire, to resume self-sustaining patterns, we hope to reestablish healthy forests that provide ecosystem services, wildlife habitat, and recreational opportunities. The Southwest Fire Science Consortium (SWFSC) is a way for managers, scientists, and policy makers to interact and share science. SWFSC's goal is to see the best science used to make management decisions and scientists working on the questions managers need answered. The SWFSC tries to bring together localized efforts to develop scientific information and to disseminate that to practitioners on the ground through an inclusive and open process. This publication would not have been possible without funding from the USDA Forest Service and the Southwest Fire Science Consortium. The views and conclusions contained in this document are those of the author(s) and should not be interpreted as representing the opinions or policies of the United States Government. Mention of trade names or commercial products does not constitute their endorsement by the United States Government or the ERI
Uranium leaching from contaminated soil utilizing rhamnolipid, EDTA, and citric acid
Get PDFBiosurfactants have recently gained attention as "green" agents that can be used to enhance the remediation of heavy metals and some organic matter in contaminated soils. The overall objective of this paper was to investigate rhamnolipid, a microbial produced biosurfactant, and its ability to leach uranium present in contaminated soil from an abandoned mine site. Soil samples were collected from two locations in northern Arizona: Cameron (site of open pit mining) and Leupp (control-no mining). The approach taken was to first determine the total uranium content in each soil using a hydrofluoric acid digestion, then comparing the amount of metal removed by rhamnolipid to other chelating agents EDTA and citric acid, and finally determining the amount of soluble metal in the soil matrix using a sequential extraction. Results suggested a complex system for metal removal from soil utilizing rhamnolipid. It was determined that rhamnolipid at a concentration of 150 mu M was as effective as EDTA but not as effective as citric acid for the removal of soluble uranium. However, the rhamnolipid was only slightly better at removing uranium from the mining soil compared to a purified water control. Overall, this study demonstrated that rhamnolipid ability to remove uranium from contaminated soil is comparable to EDTA and to a lesser extent citric acid, but, for the soils investigated, it is not significantly better than a simple water wash
Highly sensitive quantitative PCR for the detection and differentiation of Pseudogymnoascus destructans and other Pseudogymnoascus species
Get PDFWhite-nose syndrome is a fungal disease that has decimated bat populations across eastern North America. Identification of the etiologic agent, Pseudogymnoascus destructans (formerly Geomyces destructans), in environmental samples is essential to proposed management plans. A major challenge is the presence of closely related species, which are ubiquitous in many soils and cave sediments and often present in high abundance. We present a dual-probe real-time quantitative PCR assay capable of detecting and differentiating P. destructans from closely related fungi in environmental samples from North America. The assay, based on a single nucleotide polymorphism (SNP) specific to P. destructans, is capable of rapid low-level detection from various sampling media, including sediment, fecal samples, wing biopsy specimens, and skin swabs. This method is a highly sensitive, high-throughput method for identifying P. destructans, other Pseudogymnoascus spp., and Geomyces spp. in the environment, providing a fundamental component of research and risk assessment for addressing this disease, as well as other ecological and mycological work on related fungi
Neural-humoral responses during head-up tilt in healthy young white and black women
Get PDFYoung black women have higher prevalence of hypertension during pregnancy compared to white women, which may be attributable to differences in blood pressure (BP) regulation. We hypothesized that young normotensive black women would demonstrate augmented muscle sympathetic nerve activity (MSNA) and renal-adrenal responses to orthostasis. Fifteen white and ten black women (30 ± 4 vs. 32 ± 6 years; means ± SD) had haemodynamics and MSNA measured during baseline (BL), 30 and 60° head-up tilt (HUT), and recovery. Blood was drawn for catecholamines, direct renin, vasopressin, and aldosterone. BL brachial systolic BP (SBP: 107 ± 6 vs. 101 ± 9 mmHg) and diastolic BP (DBP: 62 ± 4 vs. 56 ± 7 mmHg) were higher in white women (both p < 0.05). Δ DBP (60° HUT-BL) was greater in black women compared to white (p < 0.05). Cardiac output and total peripheral resistance were similar between groups. MSNA burst frequency was higher in whites (BL: 16 ± 10 vs. 14 ± 9 bursts/min, main effect p < 0.05) and increased in both groups during HUT (60°: 39 ± 8 vs. 34 ± 13 bursts/min, p < 0.05 from BL). Noradrenaline was higher in white women during 60° HUT (60° HUT: 364 ± 102 vs. 267 ± 89 pg/ml, p < 0.05). Direct renin was higher and vasopressin and Δ aldosterone tended to be higher in blacks (BL, direct renin: 12.1 ± 5.0 vs. 14.4 ± 3.7 pg/ml, p < 0.05; BL, vasopressin: 0.4 ± 0.0 vs. 1.6 ± 3.6 pg/ml, p = 0.065; Δ aldosterone: −0.9 ± 5.1 vs. 3.8 ± 7.5 ng/ml; p = 0.069). These results suggest that young normotensive white women may rely on sympathetic neural activity more so than black women who have a tendency to rely on the renal-adrenal system to regulate BP during an orthostatic stress
Carbon stocks and climate change: management implications in northern Arizona ponderosa pine
Get PDFResearchers have observed climate-driven shifts of forest types to higher elevations in the Southwestern US and predict further migration coupled with large-scale mortality events proportional to increases in radiative forcing. Range contractions of forests are likely to impact the total carbon stored within a stand. This study examines the dynamics of Pinus ponderosa stands under three climate change scenarios in Northern Arizona using the Climate Forest Vegetation Simulator (Climate-FVS) model to project changes in carbon pools. A sample of 90 stands were grouped according to three elevational ranges; low- (1951 to 2194 m), mid- (2194 to 2499 m), and high- (2499 to 2682 m.) elevation stands. Growth, mortality, and carbon stores were simulated in the Climate-FVS over a 100 year timespan. We further simulated three management scenarios for each elevational gradient and climate scenario. Management included (1) a no-management scenario, (2) an intensive-management scenario characterized by thinning from below to a residual basal area (BA) of 18 m2/ha in conjunction with a prescribed burn every 10 years, and (3) a moderate-management scenario characterized by a thin-from-below treatment to a residual BA of 28 m2/ha coupled with a prescribed burn every 20 years. Results indicate that any increase in aridity due to climate change will produce substantial mortality throughout the elevational range of ponderosa pine stands, with lower elevation stands projected to experience the most devastating effects. Management was only effective for the intensive-management scenario; stands receiving this treatment schedule maintained moderately consistent levels of basal area and demonstrated a higher level of resilience to climate change relative to the two other management scenarios. The results of this study indicate that management can improve resiliency to climate change, however, resource managers may need to employ more intensive thinning treatments than currently proposed to achieve the best results
Seasonal cultivated and fallow cropland mapping using MODIS-based automated cropland classification algorithm
Get PDFIncreasing drought occurrences and growing populations demand accurate, routine, and consistent cultivated and fallow cropland products to enable water and food security analysis. The overarching goal of this research was to develop and test automated cropland classification algorithm (ACCA) that provide accurate, consistent, and repeatable information on seasonal cultivated as well as seasonal fallow cropland extents and areas based on the Moderate Resolution Imaging Spectroradiometer remote sensing data. Seasonal ACCA development process involves writing series of iterative decision tree codes to separate cultivated and fallow croplands from noncroplands, aiming to accurately mirror reliable reference data sources. A pixel-by-pixel accuracy assessment when compared with the U.S. Department of Agriculture (USDA) cropland data showed, on average, a producer's accuracy of 93% and a user's accuracy of 85% across all months. Further, ACCA-derived cropland maps agreed well with the USDA Farm Service Agency crop acreage-reported data for both cultivated and fallow croplands with R-square values over 0.7 and field surveys with an accuracy of >= 95% for cultivated croplands and >= 76% for fallow croplands. Our results demonstrated the ability of ACCA to generate cropland products, such as cultivated and fallow cropland extents and areas, accurately, automatically, and repeatedly throughout the growing season
Variation in prey delivered to common Black-Hawk (Buteogallus anthracinus) nests in Arizona drainage basins
Get PDFUnderstanding how raptor diets vary across local and regional scales can be important when human actions have the potential to alter prey abundances. We combined data on prey delivered to 16 Common Black-Hawk (Buteogallus anthracinus) nests in three tributaries of the Verde River, Arizona, in 2008 and 2009 with similar data reported previously (1994) for three other Arizona drainage basins to better understand variation in diet composition within and across drainage basins. Within the three drainage basins studied in 2008 and 2009, nests clustered into two groups: those along Fossil Creek, where fish and amphibians were common, and those in Wet Beaver and Oak Creek drainage basins, where reptiles and nonnative crayfish were more abundant. When data from all six drainage basins were combined, drainage basins again clustered into two groups, with prey deliveries in one cluster dominated by fish and amphibians and in the other cluster by reptiles. These results confirm the opportunistic nature of prey use by Common Black-Hawks and highlight the variation in diet that can occur both within and among drainage basins. Management targeting the eradication of nonnative crayfish or the reintroduction of native amphibians and fish could alter prey availability for this raptor species
Fact sheet: Genetic considerations for restoring forests of the southwest after severe disturbance.
Get PDFClimate change models predict increases in temperature and more frequent severe droughts and forest fires in the Southwest United States (Garfin et al. 2013). Aridity stress to forests caused by climate change will be especially severe in forests and woodlands of the Southwest because productivity is already strongly limited by low precipitation and humidity (Williams et al. 2013). Intense drought predisposes trees to disease and insect attack, such as bark beetles that have killed many trees in the Southwest in the last two decades (Raffa et al. 2008, Gaylord et al. 2013). Climate warming and fuel buildups in the Southwest are increasing wildfire-caused deforestation (Williams et al. 2010, Williams et al. 2013). There is a high risk of conversion of ponderosa pine forests to grassland or shrubs when intense burning, drought, or bark beetles cause high tree mortality, create large openings, and kill local tree seed sources (Roccaforte et al., 2012). Future increase in drought intensity caused by climate warming will reduce opportunities for ponderosa pine regeneration after deforestation (Savage et al. 2013). Moreover, climate-envelope models predict substantial shrinking of the range of ponderosa pine in the Southwest over the next century, especially at low-elevations (Rehfeldt et al. 2014).
The purpose of this fact sheet is to explain the need for using emerging knowledge about climate change and tree genetics to guide post-disturbance restoration of ponderosa pine in the Southwest
Working paper 32: An evaluation of fire regime reconstruction methods.
Get PDFFire is a fundamental disturbance process in ecology and has been a powerful agent of change in terrestrial ecosystems for millions of years. Understanding the role of fire on a landscape is critical for managing fire and forests for biodiversity, ecosystem function, and resilience to changes in climate. To better understand the role fire can play in forests today, researchers and managers have found it useful to reconstruct attributes of historical fire regimes before the onset of fire exclusion. Fire exclusion in the southwestern United States often occurred in the late 1800s, when activities such as grazing of domestic animals, logging, and fire suppression began on a widespread scale. Information about past fire regimes can be a helpful reference to guide and inform land managers about current and future fire regime characteristics, patterns, and forest structure characteristics. Management activities that benefit from understanding past fire regimes include prescribed fire, managed wildfires for resource benefit, and mechanical treatments to reduce fire risk. Six fire regime attributes are often considered: - Frequency: how often fires occur in a given area or region (see Box 1 for more detailed frequency terminology) - Seasonality: time of year - Severity: ecological effects of fire - Type: surface or crown fire - Size: area burned - Spatial complexity: pattern of severity within fire perimeter Fire intensity, which is a measure of the heat of a fire, is a seventh fire regime attribute that cannot be reconstructed directly but is inferred from fire severity. Fire severity refers to the ecological effects of fire and is often quantified by overstory tree mortality. Each fire regime attribute can be characterized by an average condition (for example, an average fire frequency of 8 years) as well as a measure of variation (for example, a range in fire frequency of 2 to 20 years). This working paper discusses several methods for reconstructing historical fire regimes: - Historical documents and photos - Dendrochronology: re-scar data - Dendrochronology: tree age, death and growth data - Forest structure data - Plant traits - Charcoal Each of these methods will be discussed in terms of advantages, disadvantages, inherent uncertainties, and assumptions as well as temporal and spatial precision. The potential value and limitations for reconstructing historical forest structure and composition with each method are also briefly covered