Southeastern Arizona Research Articles

Combining graph theory and spatially-explicit, individual-based models to improve invasive species control strategies at a regional scale

ContextInvasive species cause widespread species extinction and economic loss. There is an increasing need to identify ways to efficiently target control efforts from local to regional scales.ObjectivesOur goal was to test whether prioritizing managed habitat using different treatments based on spatial measures of connectivity, including graph-theoretic measures, can improve management of invasive species and whether the level of control effort affects treatment performance. We also explored how uncertainty in biological variables, such as dispersal ability, affects measures performance.MethodsWe used a spatially-explicit, individual-based model (sIBM) based on the American bullfrog (Lithobates catesbeianus), a globally pervasive invasive species. Simulations were informed by geographic data from part of the American bullfrog’s non-native range in southeastern Arizona, USA where they are known to pose a threat to native species.ResultsWe found that total bullfrog populations and occupancy declined in response to all treatments regardless of effort level or patch prioritization methods. The most effective spatial prioritization was effort-dependent and varied depending on spatial context, but frequently a buffer strategy was most effective. Treatments were also sensitive to dispersal ability. Performance of treatments prioritizing habitat patches using betweenness centrality improved with increasing dispersal ability, while performance of eigenvalue centrality improved as dispersal ability decreased.ConclusionsWith the careful application of connectivity measures to prioritize control efforts, similar reductions in invasive species population size and occupancy could be achieved with less than half the effort of sub-optimal connectivity measures at higher effort rates. More work is needed to determine if trait-based generalities may define appropriate connectivity measures for specific suites of dispersal abilities, demographic traits, and population dynamics.

Here’s Why Resolution Copper Wants to Mine Oak Flat

Southeastern Arizona’s “Copper Triangle” is a hot spot for high-grade deposits, thanks to ancient magmatic activity.

Effectiveness of pre-fire forest management on post-fire forest conditions in southeastern Arizona

BackgroundWestern forests in the United States are facing multiple threats that have the potential to permanently alter forest composition and structure. In particular, wildfire can either have beneficial or adverse effects on overall forest health and resilience. Monitoring and assessing the effectiveness of existing forest treatment plans for meeting forest management goals is becoming more critical to increase the capacity for managers to prepare for and accommodate uncertainty associated with changing disturbance regimes. We used a combination of fine-scale vegetation and microclimate surveys on 57 plots, active remotely sensed data (light detection and ranging: LiDAR), and high-resolution satellite imagery to evaluate the effectiveness of an existing management strategy to increase disturbance resistance and resilience of an isolated mixed-conifer forest following a recent large-scale wildfire in southeastern Arizona, USA. We specifically assessed the effectiveness of forest overstory live tree thinning treatments (silviculture) as well as understory fuel reduction treatments (fuel) for influencing post-fire abiotic and biotic conditions, reducing direct post-fire tree mortality, and increasing resilience as compared to untreated forest stands.ResultsWe found that forest silviculture and fuel reduction treatments implemented prior to a large wildfire had mixed results on post-fire fine-scale vegetation composition and structure, microclimate conditions, tree mortality, and tree resilience. Fine-scale vegetation characteristics within silviculture- and fuel-treated forest units displayed higher herbaceous diversity and decreased density of new tree snags as compared to untreated units post-fire. Relevant to seedling emergence, we found that variance in spring soil moisture content was lower overall in treated units; however, units that received overstory thinning (silviculture) treatments were also associated with higher average summer high soil temperatures as compared to untreated units. Additionally, direct tree mortality and rate of recovery of trees post-fire differed between two treatment types (silviculture and fuel reduction) when compared to untreated units and among contrasting levels of burn severity. Post-fire tree mortality and tree resilience did not differ between control and silviculture units; however, these characteristics did differ between control and fuel units. Unlike control units, probability of tree mortality changed little between burn severity categories in fuel treatments (53.4% of mortality occurring in unburned/low vs. 46.7% in moderate/high severity) and resilience increased an average of 2.04% for trees from unburned/low to moderate/high-severity burn categories.ConclusionsOur methodology could be applied to any forested system experiencing increasing intensity and frequency of wildfire. Our results indicate that post-fire forest conditions and resilience are influenced by forest management strategies, particularly fuel reduction treatments. To accommodate uncertainty associated with changing disturbance regimes and climate change, implementing post-fire and post-treatment assessments and monitoring as presented in this study will be essential for developing attainable goals and for maintaining desired forest conditions.

A reference quality genome assembly for the jewel scarab Chrysina gloriosa.

The jewel scarab Chrysina gloriosa is one of the most charismatic beetles in the United States and is found from the mountains of West Texas to the Southeastern Arizona sky islands. This species is highly sought by professional and amateur collectors worldwide due to its gleaming metallic coloration. However, the impact of the large-scale collection of this beetle on its populations is unknown, and there is a limited amount of genetic information available to make informed decisions about its conservation. As a first step, we present the genome of C. gloriosa, which we reconstructed using a single female specimen sampled from our ongoing effort to document population connectivity and the demographic history of this beetle. Using a combination of long-read sequencing and Omni-C data, we reconstructed the C. gloriosa genome at a near-chromosome level. Our genome assembly consisted of 454 scaffolds spanning 642 MB, with the 10 largest scaffolds capturing 98% of the genome. The scaffold N50 was 72 MB, and the BUSCO score was 95.5%. This genome assembly will be an essential tool to accelerate understanding C. gloriosa biology and help make informed decisions for the conservation of Chrysina and other species with similar distributions in this region. This genome assembly will further serve as a community resource for comparative genomic analysis.

Oligocene‐Miocene Exhumation of the Pinaleño Metamorphic Core Complex, Southeastern Arizona: Support for Magmatism and Plate Margin Reorganization as Controls on Regional Exhumation Trends

AbstractThe Pinaleño Mountains of southeastern Arizona is the eastern‐most metamorphic core complex in the southern U.S. and northern Mexican Cordillera. This study investigates the thermal history and exhumation record of the Pinaleño core complex using mica 40Ar/39Ar, apatite and zircon (U‐Th)/He, and apatite fission‐track thermochronometers. The Pinaleño Mountains experienced two periods of rapid cooling during the Cenozoic. The first period, from ca. 27 to 21 Ma, records tectonic exhumation related to the development of the core complex and extensional shear zone. This period was followed by a relatively quiescent interval from 21 to 13.5 Ma that records little to no exhumation. The second period of rapid cooling, from 13.5 to 11 Ma, records tectonic exhumation related to high‐angle normal faulting, characteristic of the Basin and Range province. The exhumation timing of the Pinaleño core complex matches previously recognized spatiotemporal trends in the southern Basin and Range province and indicates that core complex exhumation in this region started in southeastern Arizona (ca. 32–33°N) and migrated both northward and southward. These trends correlate well with the latitude and timing of subduction of the Pacific‐Farallon spreading ridge and the migration of the Mendocino (northward) and Rivera (southward) triple junctions. Spatiotemporal core complex exhumation trends also correlate well with regional magmatism associated with the mid‐Cenozoic flare‐up, including syn‐extensional intrusive rocks found in the footwalls of core complexes.

The high cost of movement in an arid working landscape for an endangered amphibian.

Connectivity is essential for the maintenance of genetic diversity and stability of wildlife populations. Drought and changing precipitation regimes have caused natural aquatic amphibian breeding habitats to disappear or become isolated and have led to the replacement of natural surface water with artificial livestock water tanks. Terrestrial movement is the only means of responding to aquatic threats in arid landscapes and to allow population connectivity. Aridity may present an impenetrable barrier in hydrologically fragmented environments. We used a facultatively paedomorphic and federally endangered salamander to assess the challenges of movement across arid working lands. Sonoran tiger salamanders (Ambystoma mavortium stebbinsi) are endemic to the San Rafael Valley of southeastern Arizona, United States of America, where they depend on livestock water tanks as breeding habitat. The ecology of this species' metamorphs outside of stock tanks is virtually unknown. To assess survival on the landscape during terrestrial movement we used radio-transmitters to track 78 adult metamorphosed salamanders over 2 years. Sonoran tiger salamanders moved up to 1 km from the tank edge, and average distances moved of over 400 m were higher than most Ambystoma species. However, during the study period, none reached neighboring stock tanks. We found high mortality due to predation and desiccation. Individuals that dispersed to terrestrial habitat in summer survived longer than individuals that dispersed in spring. High mortality suggests terrestrial movement is exceptionally risky and may contribute to isolated subpopulations and elevated levels of inbreeding. Conservation actions that improve and maintain artificial aquatic habitats as well as increase connectivity may improve long-term management for pond-breeding amphibians in arid regions.

Entrepreneurial community development and the everyday realities of existing enterprises

ABSTRACT Entrepreneurship and innovation are key inputs to the revitalization and sustainability of rural communities and economies. While compelling, entrepreneurial community development models heavily favor new venture start-up activities and largely overlook the needs and potential of existing enterprises. Drawing on principles of everyday life sociology and organizational culture, we explored how a sample of Southeastern Arizona ranchers confront persistent challenges by way of their daily routines, practices, and interactions. Data were collected through extensive field work involving nearly 100 hours of direct observation and semi-structured interviews with 14 participants across four ranches. The findings show the innovative characteristics of the ranchers’ everyday practices and routines and illustrate how everyday ingenuity among the ranchers drives a problem-driven mindset and immediate, short-term action. We use the insights generated to conceptualize a temporal dynamic that if integrated with entrepreneurial community development models may better foster and support innovation within existing enterprises.

New Records and Notes on the Distribution of Aquatic Insects (Coleoptera, Hemiptera) in Southeastern Arizona

New Records and Notes on the Distribution of Aquatic Insects (Coleoptera, Hemiptera) in Southeastern Arizona

Soil microbial communities along elevational gradients in the Madrean Sky Islands.

The Madrean Sky Islands are mountain ranges isolated by a 'desert sea'. This area is a biodiversity hotspot currently threatened by climate change. Here, we studied soil microbial communities along elevational gradients in eight Madrean Sky Islands in southeastern Arizona (USA). Our results showed that while elevational microbial richness gradients were weak and not consistent across different mountains, soil properties strongly influenced microbial community composition (overall composition and the abundance of key functional groups) along elevational gradients. In particular, warming is associated with a higher abundance of soil-borne fungal plant pathogens that concomitantly might facilitate upward elevational shifts of plant species released from negative plant-soil feedbacks. Furthermore, projected warming and drought in the area aggravated by anthropogenic nitrogen deposition on mountain tops (and thus, decreasing nitrogen limitation) can enhance a shift from ectomycorrhizal to arbuscular mycorrhizal fungi. Overall, these results indicate that climate change effects on plant-soil interactions might have profound ecosystem consequences.

Breeding by western Yellow-billed Cuckoos in xeroriparian habitat in southeastern Arizona

Breeding by western Yellow-billed Cuckoos in xeroriparian habitat in southeastern Arizona

Discovery of a new tarantula species from the Madrean Sky Islands and the first documented instance of syntopy between two montane endemics (Araneae, Theraphosidae, Aphonopelma): a case of prior mistaken identity.

The Chiricahua Mountains in southeastern Arizona are renowned for their exceptional biodiversity and high levels of endemism. Morphological, genomic, behavioral, and distributional data were used to report the discovery of a remarkable new tarantula species from this range. Aphonopelmajacobii sp. nov. inhabits high-elevation mixed conifer forests in these mountains, but also co-occurs and shares its breeding period with A.chiricahua-a related member of the Marxi species group-in mid-elevation Madrean evergreen oak and pine-oak woodlands. This marks the first documented case of syntopy between two montane endemics in the Madrean Archipelago and adds to our knowledge of this threatened region's unmatched tarantula diversity in the United States. An emended diagnosis and redescription for A.chiricahua are also provided based on several newly acquired and accurately identified specimens. Phylogenetic analyses of mitochondrial and genomic-scale data reveal that A.jacobii sp. nov. is more closely related to A.marxi, a species primarily distributed on the Colorado Plateau, than to A.chiricahua or the other Madrean Sky Island taxa. These data provide the evolutionary framework for better understanding the region's complex biogeographic history (e.g., biotic assembly of the Chiricahua Mountains) and conservation of these spiders.

Movement response of small mammals to burn severity reveals importance of microhabitat features

Abstract Disturbance events are increasing at a global scale, with cascading impacts to ecosystems and residents therein that include fragmentation and altered vegetation structure and composition. Such changes may disproportionately impact small mammal movements, risk perception, and community dynamics as smaller species perceive such changes at finer spatial scales. We examined movement response to burn severity, vegetation structure, and composition in Mexican woodrats (Neotoma mexicana), a common but understudied small mammal species. The study was conducted on Mt. Graham in southeastern Arizona, United States, following a fire that burned over 19,400 ha. We measured path tortuosity of woodrats translocated over patches of different burn severity. Tortuosity can indicate microhabitat selection, foraging behavior, and perceived predation risk—features affecting population-level processes that changes in community composition alone cannot fully demonstrate. We captured woodrats, released them 50 m away from their midden, and used fluorescent powder to track woodrat movement paths through areas of low–severe burn severity. We analyzed features of the resulting powder trails including straightness, average step length, fractal dimension, and squared displacement. We also compared used versus expected vegetation structure and composition along movement paths across burn severities. Analyses indicated shorter step length with increased bare ground, as well as higher squared displacement in areas with more logs. Vegetation analyses likewise showed that logs were heavily used in low-burned areas, whereas dense vegetation was avoided in highly burned areas. Burn severity alone did not have a direct effect on movement parameters, rather its influence on vegetative composition and structure appears to be most important. Selection for logs and avoidance of dense vegetation may be attributed to auditory concealment and ease of travel. With projected increases in wildfire extent and severity, this work represents an understudied approach to understanding these disturbances and their effects on ecological communities.

On the Efficacy of Monin–Obukhov and Bulk Richardson Surface-Layer Parameterizations over Drylands

Abstract Surface-layer parameterizations for heat, mass, momentum, and turbulence exchange are a critical component of the land surface models (LSMs) used in weather prediction and climate models. Although formulations derived from Monin–Obukhov similarity theory (MOST) have long been used, bulk Richardson (Rib) parameterizations have recently been suggested as a MOST alternative but have been evaluated over a limited number of land-cover and climate types. Examining the parameterizations’ applicability over other regions, particularly drylands that cover approximately 41% of terrestrial land surfaces, is a critical step toward implementing the parameterizations into LSMs. One year (1 January–31 December 2018) of eddy covariance measurements from a 10-m tower in southeastern Arizona and a 200-m tower in western Texas were used to determine how well the Rib parameterizations for friction velocity (), sensible heat flux (H), and turbulent kinetic energy (TKE) compare against MOST-derived parameterizations of these quantities. Independent of stability, wind speed regime, and season, the Rib and TKE parameterizations performed better than the MOST parameterizations, whereas MOST better represented H. Observations from the 200-m tower indicated that the parameterizations’ performance degraded as a function of height above ground. Overall, the Rib parameterizations revealed promising results, confirming better performance than traditional MOST relationships for kinematic (i.e., ) and turbulence (i.e., TKE) quantities, although caution is needed when applying the Rib H parameterizations to drylands. These findings represent an important milestone for the applicability of Rib parameterizations, given the large fraction of Earth’s surface covered by drylands. Significance Statement Weather forecasting models rely upon complex mathematical relationships to predict temperature, wind, and moisture. Monin–Obukhov similarity theory (MOST) has long been used to forecast these quantities near the land surface, even though MOST’s limitations are well known in the scientific community. Researchers have suggested an alternative to MOST called the bulk Richardson (Rib) approach. To allow for the Rib approach to be used in weather forecasting models, the approach needs to be tested over different land-cover and climate types. In this study, we applied the Rib approach to dry areas of the United States and found that the approach better represented turbulence variables than MOST relationships. These findings are an important step toward using Rib relationships in weather forecasting models.

Habitat selection of Gould’s wild turkeys in southeastern Arizona

In semi-arid environments, resources necessary for survival may be unevenly distributed across the landscape. Gould’s wild turkeys (Meleagris gallopavo mexicana) are spatially restricted to mountainous semi-arid areas of southwestern United States and Mexico, and information on their distribution and habitat use is limited. We described how landcover type and topographical features influenced space use and habitat selection by Gould’s wild turkeys in southeastern Arizona. We used GPS data from 51 Gould’s wild turkeys to describe resource selection during 2016–2017 in southeastern Arizona, USA. We estimated home ranges and calculated resource selection functions using distance from landcover types, slope, aspect, and elevation at used locations and random locations within individual home ranges. Gould’s wild turkeys selected areas closer to pine forest and water. Likewise, Gould’s wild turkeys selected locations with moderate elevations of 1641 ± 235 m (range = 1223–2971 m), and on north and west facing slopes with a 10° ± 8.5 (range = 0.0–67.4°) incline. Our findings suggest that conserving portions of the landscape with appropriate topography and landcover types as described above will promote habitat availability for Gould’s wild turkeys.

Constructing a borderlands in the ancient international four corners: Settlement layout, architecture, and mortuary practices in thirteenth through fifteenth century CE villages along the contemporary united states-Mexico border

Archaeological interpretations for the seemingly sudden introduction of new types of material culture or cultural practice often include attribution to the arrival of a migrant population as part the construction of a periphery or frontier zone. In the International Four Corners area of the American Southwest/Mexican Northwest, archaeologists often correlate the ascendancy of Paquimé in the late thirteenth century CE with the development of a northern periphery in southwestern New Mexico. Simultaneously, sites in far southeastern Arizona became partially integrated into the Salado phenomenon. I evaluate architecture, settlement, and mortuary data from 26 sites with respect to existing models. Given ongoing historian discourse regarding Indigenous borderlands during European colonization, I advocate a model enabling the occurrence of borderlands construction prior to colonization and lacking a predominate hierarchical society. I conclude that the inhabitants of the International Four Corners region situated themselves within multiple inter- and intra-regional zones of interaction and that existing models of frontiers and edge regions are inadequate to address the variability present, but that of the borderlands does as it recognizes relationships to adjacent culture cores as influential but also centers the local inhabitants and their agency.

Use of nest boxes, reproductive success, and sex ratio in two screech-owls in the Peloncillo Mountains of southeastern Arizona

Use of nest boxes, reproductive success, and sex ratio in two screech-owls in the Peloncillo Mountains of southeastern Arizona

Phenotypic diversity facilitates niche partitioning in a sky island assemblage of spiny lizards

Abstract If closely related species should be more similar and therefore more likely to compete for resources, why do we see so many examples of species-rich congeneric communities in nature? To avoid competition, many species possess suites of traits associated with differential resource use – or ecomorphologies – that promote niche differentiation with co-occurring species. Yet, the axes through which niche partitioning evolves and the traits involved are still poorly understood in most systems. Island systems, in which species interactions can form strong forces of selection due to limited resources, provide valuable insights into how ecomorphological diversity contributes to coexistence. Here, we examined axes of resource use and morphological traits that facilitate niche partitioning in a community of spiny lizards (genus Sceloporus) in a sky island system, the Chiricahua Mountains of southeastern Arizona, USA. By quantifying structural, temporal and thermal niche use for over 300 co-occurring lizards from four species over three field seasons, we show that sympatric species diverge primarily in perch height and type, but also in thermal and temporal resource use. Our results further demonstrate interspecific divergence in a suite of phenotypic traits known to covary with ecology in other lizard radiations, including body size, scale size, hindlimb length, foot length and dorsal coloration. Studies of niche partitioning and ecomorphology, especially of closely related species, deepen our understanding of how diverse communities assemble and how morphological diversity accumulates across the tree of life, and our findings highlight the importance of examining multiple axes of resource use to better understand these processes.

A Spatiotemporal Characterization of Water Resource Conditions and Demands as Influenced by the Hydrogeologic Framework of the Willcox Groundwater Basin, Southeastern Arizona, USA

In the Willcox Groundwater Basin (WGB), increasing rates of agricultural groundwater withdrawal have led to significant regional groundwater level decline, threatening the basin’s long-term water resource security. Updated characterization of the basin’s water resource conditions and agricultural water demand is critically important for informing groundwater resource management efforts. We developed the hydrogeologic framework of the WGB and linked groundwater level data with land cover classification data to provide a spatiotemporal assessment of water resource conditions and agricultural development in the WGB. A correlation analysis evaluated the degree of association between the basin’s mean annual depth-to-groundwater and agricultural land cover extent. Results of this study indicate that between 2008 and 2021, agricultural land cover in the WGB increased by 29%. The average rate of groundwater level change in the basin’s measured wells was calculated at −13.8 m between 2006 and 2021. We found a strong correlation between the basin’s mean annual measured depth-to-groundwater and the annual agricultural land cover extent, further reinforcing the understanding of agricultural water use in the basin as a principal driver of groundwater level decline. The methodological framework employed proved a simple and effective way to assess groundwater resources as influenced by geology and land use. The outcomes of this study provide critical information toward improved water resources management by providing an integrated understanding of local hydrogeology, groundwater level variability, and changes in agricultural land cover in arid inland basins such as those found in Arizona, USA.

Distribution and habitat of Ocelot (Leopardus pardalis) in Sonora, México

The ocelot (Leopardus pardalis) ranges from northeastern Argentina to southern Texas and southeastern Arizona. It is listed as Endangered in Mexico and the United States. Previous works on ocelots in Sonora, found them occupying different habitats, including tropical deciduous forest, thornscrub, desert grassland, oak woodland, and pine-oak forest, avoiding the driest areas of the Sonoran Desert. The majority of our records are from camera traps, with indirect records from tracks. We analyzed images and videos of more than 100 camera traps used to monitor wildlife in ranches and natural protected areas of Sonora. Cameras were set at an altitude of 70 to 100 cm above ground, some were baited with a sardine-tomato mixture, others were not, the majority were set in areas where other species were the main objective. We obtained 147 recent records from 2015 to 2021 and 28 previous records of ocelots in Sonora. Ocelots occur in the eastern half of Sonora, avoiding areas with less than 400 mm of annual rainfall in the eastern and northwestern Sonoran Desert. Ocelots have been recorded from 53 to 2,151 m elevation (av. 996 m). 21 images in nine localities show females with kittens, indicating breeding populations. In southern and east-central Sonora, ocelots live in tropical deciduous forest, and foothills thornscrub. At Maycoba east of Yécora, in Sierra Huachinera and in the Sky Islands Mountain ranges in northeastern Sonora, ocelots live in temperate vegetation, including desert grassland, oak woodland, and pine-oak forest. Ocelots have been recorded in riparian habitats, transecting other vegetation types in the principal rivers of the state: Ríos Bavispe-Yaqui, Mayo, and Sonora, which drain the Sierra Madre Occidental, the Sky Island Region and southeastern Arizona to the Gulf of California, providing dispersal corridors. Other medium sized rivers provide corridors for the dispersal of ocelots, such as Río Mátape in central Sonora, and Ríos Cocóspera, San Pedro, and Santa Cruz in the north. The nearest Sonoran populations to Arizona are in the Sierra El Alacrán and Río Cocóspera on Rancho El Aribabi.

Agricultural Intensification, Regional Differentiation, and Incipient Village Formation: Early Formative Period Patterning in the San Carlos Safford Area, Southeastern Arizona

Archaeologists commonly interpret the Early Formative period through the lens of ceramic technology and as a significant break from Late Archaic or Early Agricultural period lifeways; however, the local changes underlying this pattern often remain obscure. In this paper, we evaluate the existing literature for the Early Formative period the San Carlos Safford Area of southeastern Arizona and discern the accuracy of the current understanding of the local chronology, material culture, and regional patterning. Through a systematic examination of chronological, ceramic, and architectural data, we advocate for several interpretive shifts in the Early Formative period and characterize regional patterning during this temporal interval. We relate the emergence of larger villages as an adaptive strategy against a significant climatic event in the early to mid-sixth century yet also demonstrate the incongruities present between the San Carlos Safford Area and far better studied areas within central and southern Arizona.