Southeastern Arizona Research Articles

Vegetative litter decomposition along urban ephemeral streams in Southeastern Arizona

Riparian areas provide a wide range of ecosystem services. Population growth in Arizona has led to the urban encroachment of riparian areas. Urbanization alters microclimatic conditions that can affect ecosystems processes. This study investigated the impacts of urbanization levels on ecosystems processes (decomposition rates) of riparian areas along ephemeral streams. Nine sites were selected within Marana, Arizona with three housing density levels: high (7–8 houses ha−1), moderate (2.5–4.5 houses ha−1) and low (<1.5 houses ha−1). The litter bag method was used for the three dominant woody species: Parkinsonia microphylla, Larrea tridentata, and Acacia constricta. Litter bags were collected prior to and after the winter rainy and summer monsoon seasons. The variables studied were carbon, nitrogen and lignin content, carbon to nitrogen ratio and mass loss. Soil temperature and moisture, air temperature, relative humidity and precipitation were also recorded. The litter variables mostly were not affected by housing density. The regression analysis for mass loss on the litter and microclimate variables indicated lignin content and carbon to nitrogen ratio as the most important factors. Most other studies indicate moisture availability as the most limiting factor. The moisture in these areas could have been sufficient because of the proximity to the ephemeral stream thus leading to different results. Overall, the decomposition processes along ephemeral streams in this region are resilient to changes related to these urbanization levels. Setting aside small riparian areas along ephemeral streams appears to aid in their preservation and is recommended for future urban developments.

Summer Soil Moisture Spatiotemporal Variability in Southeastern Arizona

Abstract Soil moisture is important for many applications, but its measurements are lacking globally and even regionally. The Walnut Gulch Experimental Watershed (WGEW) in southeastern Arizona has measured near-surface 5-cm soil moisture with 19 in situ probes since 2002 within its 150 km2 area. Using various criteria to identify erroneous data, it is found that in any given period from 1 July to 30 September from 2002 to 2011, 13–17 of these probes were producing reasonable data, and this is sufficient to estimate area-averaged seasonal soil moisture. A soil water balance model is then developed using rainfall as its only input to spatially extrapolate soil moisture estimates to the 88 rain gauges located within the watershed and to extend the measurement period to 56 years. The model is calibrated from 2002 to 2011 so that the daily in situ and modeled soil moisture time series have a high average correlation of 0.89 and a root-mean-square deviation of 0.032 m3 m−3. By interpolating modeled soil moisture from the 88 rain gauges to a 100-m gridded domain over WGEW, it is found that spatial variability often increases when 88 (rather than 13–17) estimates are taken. While no trend in the spatial average surface soil moisture is found, large variability in the spatial average soil moisture from 1 July to 30 September is observed from year to year, ranging from 0.05 to 0.09 m3 m−3. In addition to spatiotemporal analysis of WGEW, this gridded soil moisture product from 1956 to 2011 can be used for validation of satellite-based and reanalysis products and land surface models.

Pherbellia anitae, a New Species of Snail-Killing Fly (Diptera: Sciomyzidae) from Arizona

Abstract. Pherbellia anitae Foote, sp. nov., from southeastern Arizona, is described, and the male postabdomen is illustrated.

Supplement to the revision of the genus Eremosaprinus Ross, 1939 (Coleoptera, Histeridae, Saprininae): new distributional data and description of a new species from Arizona, U.S.A.

A new species of the genus Eremosaprinus Ross, 1939, E. warneri, is described from southeastern Arizona, USA, and incorporated into the identification key for the genus. Description of the new species is supplemented with SEM micrographs and drawings of sensory structures of the antenna and male genitalia. New distribution data on four species, E. distinctus Lundgren, 1992, E. hubbardi (Wenzel, 1939), E. minimus Tishechkin & Lackner, 2012, and E. unguiculatus (Ross, 1939), are also provided.

Latest Pleistocene–Holocene debris flow activity, Santa Catalina Mountains, Arizona; Implications for modern debris-flow hazards under a changing climate

Hazard mitigation for extreme events such as debris flows requires geologic mapping and chronologic information, particularly for alluvial fans near mountain fronts in the southwestern United States. In July 2006, five consecutive days of monsoonal storms caused hundreds of debris flows in southeastern Arizona, particularly in the southern Santa Catalina Mountains north of Tucson. Before 2006, no historical debris flows from the Santa Catalina Mountains reached the populated mountain front, although abundant evidence of prehistoric debris flows is present on downslope alluvial fans. We used a combination of surficial geologic mapping and 10Be exposure dating to produce a debris-flow history for Pima and Finger Rock Canyons. The largest debris flows, of latest Pleistocene to early Holocene age, covered much of the apices of alluvial fans formed at the mouths of these canyons and extended up to 3km downslope. These debris-flow deposits were inset against higher and older alluvial surfaces with few debris-flow deposits of late Pleistocene age. The 10Be ages in this study have considerable scatter for surfaces believed to be of uniform age, indicating the dual possibilities of inheritance from previous cosmic-ray exposure, as well as the potential for composite deposits derived from numerous debris flows. We then used an empirical inundation model, LAHARZ, to assess probable magnitudes of the older debris flows to evaluate possible initiation mechanisms. In-channel and terrace storage within the canyons is not sufficient to generate volumes likely needed to produce the larger late Pleistocene to early Holocene debris-flow deposits. The abundance of latest Pleistocene and early Holocene deposits suggests that large debris flows were generated during the instability associated with climate and vegetation changes at the Pleistocene–Holocene transition. Under present watershed conditions with limited sediment supplies, modern debris-flow hazards are generally limited to within mountains and near mountain fronts.

A New Variety ofChoisya arizonica(Rutaceae) from Arizona, U.S.A.

A new variety of the evergreen shrub Choisya arizonica Standl. (Rutaceae) is described. It differs from the typical form in having longer and broader leaflets and thus larger leaves. The new variety C. arizonica var. amplophylla Toolin occurs in a few localities in southeastern Arizona with igneous rock substrates, rather than on soils derived from limestone substrates normally colonized by the species.

Densities of Agrilus auroguttatus and Other Borers in California and Arizona Oaks

We investigated within-tree population density of a new invasive species in southern California, the goldspotted oak borer, Agrilus auroguttatus Schaeffer (Coleoptera: Buprestidae), with respect to host species and the community of other borers present. We measured emergence hole densities of A. auroguttatus and other borers on the lower stem (bole) of naïve oaks at 18 sites in southern California and on co-evolved oaks at seven sites in southeastern Arizona. We sampled recently dead oaks in an effort to quantify the community of primary and secondary borers associated with mortality—species that were likely to interact with A. auroguttatus. Red oaks (Section Lobatae) produced greater densities of A. auroguttatus than white oaks (Section Quercus). On red oaks, A. auroguttatus significantly outnumbered native borers in California (mean ± SE of 9.6 ± 0.7 versus 4.5 ± 0.6 emergence holes per 0.09 m2 of bark surface), yet this was not the case in Arizona (0.9 ± 0.2 versus 1.1 ± 0.2 emergence holes per 0.09 m2). In California, a species that is taxonomically intermediate between red and white oaks, Quercus chrysolepis (Section Protobalanus), exhibited similar A. auroguttatus emergence densities compared with a co-occurring red oak, Q. kelloggii. As an invasive species in California, A. auroguttatus may affect the community of native borers (mainly Buprestidae and Cerambycidae) that feed on the lower boles of oaks, although it remains unclear whether its impact will be positive or negative.

Genetic and morphological contrasts between wild and anthropogenic populations of Agave parryi var. huachucensis in south-eastern Arizona.

At least seven species of Agave, including A. parryi, were cultivated prehistorically in Arizona, serving as important sources of food and fibre. Many relict populations from ancient cultivation remain in the modern landscape, offering a unique opportunity to study pre-Columbian plant manipulation practices. This study examined genetic and morphological variation in six A. p. var. huachucensis populations of unknown origin to compare them with previous work on A. parryi populations of known origin, to infer their cultivation history and to determine whether artificial selection is evident in populations potentially managed by early agriculturalists. Six A. p. var. huachucensis and 17 A. parryi populations were sampled, and morphometric, allozyme and microsatellite data were used to compare morphology and genetic structure in purportedly anthropogenic and wild populations, as well as in the two taxa. Analysis of molecular variance and Bayesian clustering were performed to partition variation associated with taxonomic identity and hypothesized evolutionary history, to highlight patterns of similarity among populations and to identify potential wild sources for the planting stock. A p. var. huachucensis and A. parryi populations differed significantly both morphologically and genetically. Like A. parryi, wild A. p. var. huachucensis populations were more genetically diverse than the inferred anthropogenic populations, with greater expected heterozygosity, percentage of polymorphic loci and number of alleles. Inferred anthropogenic populations exhibited many traits indicative of past active cultivation: greater morphological uniformity, fixed heterozygosity for several loci (non-existent in wild populations), fewer multilocus genotypes and strong differentiation among populations. Where archaeological information is lacking, the genetic signature of many Agave populations in Arizona can be used to infer their evolutionary history and to identify potentially fruitful sites for archaeological investigation of ancient settlements and cultivation practices. The same approach can clearly be adopted for other species in similar situations.

Top predator removals have consistent effects on large species despite high environmental variability

Top predator losses affect a wide array of ecological processes, and there is growing evidence that top predators are disproportionately vulnerable to environmental changes. Despite increasing recognition of the fundamental role that top predators play in structuring communities and ecosystems, it remains challenging to predict the consequences of predator extinctions in highly variable environments. Both biotic and abiotic drivers determine community structure, and manipulative experiments are necessary to disentangle the effects of predator loss from other co‐occurring environmental changes. To explore the consistency of top predator effects in ecological communities that experience high local environmental variability, we experimentally removed top predators from arid‐land stream pool mesocosms in southeastern Arizona, USA, and measured natural background environmental conditions. We inoculated mesocosms with aquatic invertebrates from local streams, removed the top predator Abedus herberti (Hemiptera: Belostomatidae) from half of the mesocosms as a treatment, and measured community divergence at the end of the summer dry season. We repeated the experiment in two consecutive years, which represented two very different biotic and abiotic environments. We found that some of the effects of top predator removal were consistent despite significant differences in environmental conditions, community composition, and colonist sources between years. As in other studies, top predator removal did not affect overall species richness or abundance in either year, and we observed inconsistent effects on community and trophic structure. However, top predator removal consistently affected large‐bodied species (those in the top 1% of the community body size distribution) in both years, increasing the abundance of mesopredators and decreasing the abundance of detritivores, even though the identity of these species varied between years. Our findings highlight the vulnerability of large taxa to top predator extirpations and suggest that the consistency of observed ecological patterns may be as important as their magnitude.

Data fusion and porphyry copper prospectivity models, southeastern Arizona

Mineral exploration programs commonly use a combination of geological, geophysical and remotely sensed data to detect sets of optimal conditions for potential ore deposits. Prospectivity mapping techniques can integrate and analyse these digital geological data sets to produce maps that identify where optimal conditions converge. Three prospectivity mapping techniques – weights of evidence, fuzzy logic and a combination of these two methods – were applied to a 32,000km2 study area within the southeastern Arizona porphyry Cu district and then assessed based on their ability to identify new and existing areas of high mineral prospectivity. Validity testing revealed that the fuzzy logic method using membership values based on an exploration model identified known Cu deposits considerably better than those that relied solely on weights of evidence, and slightly better than those that used a combination of weights of evidence and fuzzy logic. This led to the selection of the prospectivity map created using the fuzzy logic method with membership values based on an exploration model. Three case study areas were identified that comprise many critical geological and geophysical characteristics favourable to hosting porphyry Cu mineralisation, but not associated with known mining or exploration activity. Detailed analysis of each case study has been performed to promote these areas as potential targets and to demonstrate the ability of prospectivity modelling techniques as useful tools in mineral exploration programs.

Sawflies (Hymenoptera: Symphyta) in a Juniper—Oak—rassland Habitat in Southern Arizona

We sampled a juniper-oak-grassland habitat in southeastern Arizona for Symphyta over a seven-year period. Collections included 27 species of Symphyta: 1 Xyelidae, 5 Pergidae, 1 Diprionidae, 16 Argidae, and 4 Tenthredinidae. The peak season for sawflies is July through September, coinciding with the rainy season. Five new species are described, Acordulecera brevis Smith, A. tristis Smith, and A. comoa Smith (Pergidae), and Eustromboceros arizonicus Smith and E. alboclypea Smith (Tenthredinidae). Previously unknown males are described for Sphacophilus apiculus Smith, Zynzus luteiventris (Cameron) (Argidae), and Susana rufa Smith (Tenthredinidae). Zynzus himus Smith is a new record for the United States, and Periclista is a new generic record for Arizona.

An Examination of Meteorological and Soil Moisture Conditions in the Babocomari River Basin before the Flood Event of 2008

Abstract The NOAA Hydrometeorology Testbed (HMT) program has deployed a soil moisture observing network in the Babocomari River basin located in southeastern Arizona. The Babocomari River is a major tributary of the San Pedro River. At 0000 UTC 23 July 2008, the second-highest flow during the period of record was measured just upstream of the location where the Babocomari River joins the main channel of the San Pedro River. Upper-air and surface meteorological observations and Special Sensor Microwave Imager (SSM/I) satellite images of integrated water vapor were used to establish the synoptic and mesoscale conditions that existed before the flood occurred. The analysis indicates that a weak Gulf of California surge initiated by Hurricane Fausto transported a warm moist tropical air mass into the lower troposphere over southern Arizona, setting the stage for the intense, deep convection that initiated the flooding on the Babocomari River. Observations of soil moisture and precipitation at five locations in the basin and streamflow measured at two river gauging stations enabled the documentation of the hydrometeorological conditions that existed before the flooding occurred. The observations suggest that soil moisture conditions as a function of depth, the location of semi-impermeable layers of sedimentary rock known as caliche, and the spatial distribution of convective precipitation in the basin confined the flooding to the lower part of the basin. Finally, the HMT soil moisture observations are compared with soil moisture products from the NOAA/NWS/NCEP Noah land surface model.

Evaluation of the importance of clay confining units on groundwater flow in alluvial basins using solute and isotope tracers: the case of Middle San Pedro Basin in southeastern Arizona (USA)

As groundwater becomes an increasingly important water resource worldwide, it is essential to understand how local geology affects groundwater quality, flowpaths and residence times. This study utilized multiple tracers to improve conceptual and numerical models of groundwater flow in the Middle San Pedro Basin in southeastern Arizona (USA) by determining recharge areas, compartmentalization of water sources, flowpaths and residence times. Ninety-five groundwater and surface-water samples were analyzed for major ion chemistry (water type and Ca/Sr ratios) and stable (18O, 2H, 13C) and radiogenic (3H, 14C) isotopes, and resulting data were used in conjunction with hydrogeologic information (e.g. hydraulic head and hydrostratigraphy). Results show that recent recharge (<60 years) has occurred within mountain systems along the basin margins and in shallow floodplain aquifers adjacent to the San Pedro River. Groundwater in the lower basin fill aquifer (semi confined) was recharged at high elevation in the fractured bedrock and has been extensively modified by water-rock reactions (increasing F and Sr, decreasing 14C) over long timescales (up to 35,000 years BP). Distinct solute and isotope geochemistries between the lower and upper basin fill aquifers show the importance of a clay confining unit on groundwater flow in the basin, which minimizes vertical groundwater movement.

Covariate selection with iterative principal component analysis for predicting physical soil properties

Local and regional soil data can be improved by coupling new digital soil mapping techniques with high resolution remote sensing products to quantify both spatial and absolute variation of soil properties. The objective of this research was to advance data-driven digital soil mapping techniques for the prediction of soil physical properties at high spatial resolution using auxiliary data in a semiarid ecosystem in southeastern Arizona, USA. An iterative principal component analysis (iPCA) data reduction routine of reflectance and elevation covariate layers was combined with a conditioned Latin Hypercube field sample design to effectively capture the variability of soil properties across the 6250ha study area. We sampled 52 field sites by genetic horizon to a 30cm depth and determined particle size distribution, percent coarse fragments, Munsell color, and loss on ignition. Comparison of prediction models of surface soil horizons using ordinary kriging and regression kriging indicated that ordinary kriging had greater predictive power; however, regression kriging using principal components of covariate data more effectively captured the spatial patterns of soil property–landscape relationships. Percent silt and soil redness rating had the smallest normalized mean square error and the largest correlation between observed and predicted values, whereas soil coarse fragments were the most difficult to predict. This research demonstrates the efficacy of coupling data reduction, sample design, and geostatistical techniques for effective spatial prediction of soil physical properties in a semiarid ecosystem. The approach applied here is flexible and data-driven, allows incorporation of wide variety of numerically continuous covariates, and provides accurate quantitative prediction of individual soil properties for improved land management decisions and ecosystem and hydrologic models.

Geoarchaeological dating of Holocene stream terraces along the San Pedro River, southeastern Arizona, USA

Three Pleistocene and four Holocene floodplain terraces were differentiated along the San Pedro River in southeastern Arizona during a geological mapping project conducted by the Arizona Geological Survey. We used archaeological chronometric data to refine age estimates for the Holocene surfaces that had been initially based on only geomorphic and pedologic criteria. Eight archaeological sites deeply buried in the fill of the most extensive Holocene terrace map unit (Qy2r) yielded 10 radiocarbon dates and temporally diagnostic San Pedro complex (3150–1900 cal BP) artifacts. Twenty sites recorded on the surface of Qy2r terrace treads contained numerous temporally diagnostic Hohokam (1950–500 cal BP) ceramic sherds and features. The age constraints provided by these archaeological materials suggest that the Qy2r terrace fill was deposited primarily between 4500 and 1000 cal BP, with only a thin veneer of flood deposits added between 1000 and 100 cal BP. This late Holocene to historical (4500–100 cal BP) age estimate is consistent with other alluvial histories in the greater Gila River drainage basin and supplants our initial geologically based latest Holocene to historical (<2000 cal BP) Qy2r age estimate. The archaeologically derived maximum age estimate for Qy2r also provides a minimum age for the topographically higher and older Qy1r terrace, prompting us to revise our original, early to late Holocene age estimate for Qy1r to an early to middle Holocene age range of 11,500–4500 cal BP. The post-A.D. 1850 historical age we originally proposed for the Qy3r terrace deposits inset into Qy2r, however, is consistent with the presence of four historical period surface sites and a concordant absence of surface and buried prehistoric sites.

A description of small gomphotheriid (Mammalia, Proboscidea) manuses from the earliest Pleistocene 111 Ranch Beds, southeast Arizona, USA

A partial left and right manus of a gomphotheriid are described from earliest Pleistocene deposits of 111 Ranch in southeastern Arizona, USA. The discovery of these well preserved manuses provides a rare opportunity to describe these elements of a gomphotheriid in North America. I provide detailed descriptions and measurements as well as comparisons of the manuses with those of other extant and extinct proboscideans. Analyses of the manuses indicate it was a small gomphotheriid, possibly a small female, having morphological attributes more similar to other gomphotheriids, then elephantids and mammutids. The gomphotheriids Stegomastodon and Rhynchotherium have both been previously reported from 111 Ranch. Michael R. Pasenko. Environmental Planning Group, 4141 North 32nd Street, Suite 102, Phoenix, Arizona, 85018, USA, mammut501@yahoo.com, Mpasenko@epgaz.com

Home range characteristics of Mexican Spotted Owls in the Rincon Mountains, Arizona

Abstract We studied a small isolated population of Mexican Spotted Owls (Strix occidentalis lucida) from 1996–1997 in the Rincon Mountains of Saguaro National Park, southeastern Arizona, USA. All mixed-conifer and pine-oak forest patches in the park were surveyed for Spotted Owls, and we located, captured, and radio-tagged 10 adult birds representing five mated pairs. Using radio-telemetry, we examined owl home range characteristics, roost habitat, and monitored reproduction within these five territories. Breeding season (Mar–Sep) home range size for 10 adult owls (95% adaptive kernel isopleths) averaged 267 ha (±207 SD), and varied widely among owls (range 34–652 ha). Mean home range size for owl pairs was 478 ha (±417 ha SD), and ranged from 70–1,160 ha. Owls that produced young used smaller home ranges than owls that had no young. Six habitat variables differed significantly between roost and random sites, including: percent canopy cover, number of trees, number of vegetation layers, average height of ...

Associations of wintering birds with habitat in semidesert and plains grasslands in Arizona

Abstract We studied associations with winter habitat for seven species of birds, one species-group (eastern and western meadowlarks combined), and total sparrows at seven sites in the semidesert and plains grasslands of southeastern Arizona from 1999–2001, sampling with mist-nets and survey-transects. We measured structure and composition of vegetation, assessing vegetative differences among sites, and modeled associations between indices of avian abundance and six vegetative variables using generalized linear models. For all vegetative variables, there were significant differences among sites. Numbers of northern harriers (Circus cyaneus) were positively associated with total number of sparrows. Indices of abundance for individual species of birds were statistically correlated with various measures of structure and composition of vegetation. In particular, grasshopper (Ammodramus savannarum) and vesper (Pooecetes gramineus) sparrows were negatively associated with amount of bare ground; horned larks (Ere...

Madreallecula MccleveiKanda (Coleoptera: Tenebrionidae: Alleculinae: Alleculini), New Genus and New Species of Comb-Clawed Beetle from Arizona, USA

Abstract Madreallecula mcclevei Kanda, new genus and new species, is described from southeastern Arizona. This genus belongs to the subtribe Alleculina and is distinguished from other North American genera by its moniliform antennae and distally widened clypeus.

Nesting Habitat and Productivity of Swainson's Hawks in Southeastern Arizona

We studied Swainson's Hawks (Buteo swainsoni) in southeastern Arizona to assess the status of the local breeding population. Nest success (≥1 young fledged) was 44.4% in 1999 with an average of 1.43 ± 0.09 (SE) young produced per successful pair. Productivity was similar in 2000, with 58.2% nesting success and 1.83 ± 0.09 fledglings per successful pair. Mesquite (Prosopis velutina) and cottonwood (Populus fremontii) accounted for >50% of 167 nest trees. Nest trees were taller than surrounding trees and random trees, and overall there was more vegetative cover at nest sites than random sites. This apparent requirement for cover around nest sites could be important for management of the species in Arizona. However, any need for cover at nest sites must be balanced with the need for open areas for foraging. Density of nesting Swainson's Hawks was higher in agriculture than in grasslands and desert scrub. Breeding pairs had similar success in agricultural and nonagricultural areas, but the effect of rapid and widespread land-use change on breeding distribution and productivity continues to be a concern throughout the range of the species.Estudiamos a Buteo swainsoni en el sureste de Arizona para evaluar el estado de la población reproductiva local. El éxito de nidificación (≥1 pichón que deja el nido) fue 44.4% en 1999 con un promedio de 1.43 ± 0.09 (DE) pichones producidos por pareja exitosa. La productividad fue similar en el 2000, con 58.2% de éxito de nidificación y 1.83 ± 0.09 volantones por pareja exitosa. Prosopis velutina y Populus fremontii representaron >50% de 167 árboles nido. Los árboles nido fueron más altos que los árboles que los rodeaban y que los árboles elegidos al azar, y en general hubo mayor cobertura vegetal en los sitios de nidificación que en los sitios elegidos al azar. Este requerimiento aparente de cobertura alrededor de los sitios de nidificación puede ser importante para el manejo de la especia en Arizona. Sin embargo, cualquier necesidad de cobertura en sitios de nidificación debe ser balanceada con la necesidad de áreas abiertas para forrajeo. La densidad de individuos reproductivos de B. swainsoni fue mayor en tierras agrícolas que en pastizales y matorrales desérticos. Las parejas reproductivas tuvieron un éxito similar en áreas agrícolas y no agrícolas, pero el efecto del cambio rápido y extenso de uso del suelo en las distribuciones reproductivas y en la productividad continúa siendo un problema a lo largo de la distribución de la especie.