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Articles 1 - 20 of 20
Full-Text Articles in Desert Ecology
Climate And Gypsum Parent Material Shape Biocrust Communities And Moss Ecology In The Chihuahuan And Mojave Deserts, Nicole Pietrasiak, Katelyn G. Gobbie, Brian Jusko, Rebecca E. Drenovsky
Climate And Gypsum Parent Material Shape Biocrust Communities And Moss Ecology In The Chihuahuan And Mojave Deserts, Nicole Pietrasiak, Katelyn G. Gobbie, Brian Jusko, Rebecca E. Drenovsky
Life Sciences Faculty Research
Biological soil crust communities (biocrusts) establishing on gypsum soils have been well-documented for their prolific appearance and rich diversity of lichens and bryophytes. However, studies characterizing gypsum biocrusts have occurred primarily outside of the U.S., most of which lack comparisons to other soil types. We conducted intensive field surveys to evaluate the ground cover and frequency of biocrust functional groups and moss species on gypsum and non-gypsum soils in the U.S. regions with the most extensive gypsum outcrops, the northern Chihuahuan and eastern Mojave Deserts. Study sites were stratified by geomorphology and paired, so that every gypsum site was matched …
Synecological Response Of Spring Benthic Prokaryotes And Macroinvertebrates To Paleozoic Roof Pendant-Derived Calcium, Ariel D. Friel, Khaled Pordel, Zachary Meyers, Cale O. Seymour, Nicole J. Thomas, Fred M. Philips, Jeffrey R. Knott, Donald W. Sada, Laura Rademacher, Marty Frisbee, Brian P. Hedlund
Synecological Response Of Spring Benthic Prokaryotes And Macroinvertebrates To Paleozoic Roof Pendant-Derived Calcium, Ariel D. Friel, Khaled Pordel, Zachary Meyers, Cale O. Seymour, Nicole J. Thomas, Fred M. Philips, Jeffrey R. Knott, Donald W. Sada, Laura Rademacher, Marty Frisbee, Brian P. Hedlund
Life Sciences Faculty Research
Despite the ecological significance of desert springs, little is known about relationships between spring hydrogeochemistry and ecology, particularly over multiple trophic levels. Here, we surveyed microbial communities (bacteria and archaea) and benthic macroinvertebrate (BMI) communities in springs that recharge through granitoid bedrock in Owens Valley, CA, to determine whether subtle geochemical differences imparted by metamorphosed roof pendant weathering in the source area affect spring ecosystems. Relative to other springs, roof-pendant-recharged springs were characterized by elevated (1) Ca2+/Na+, Ca2+/Mg2+, and divalent/monovalent cation ratios, (2) relative abundance of taxa inferred to be benthic aerobes and prosthecate/stalked bacteria, and (3) abundance and diversity …
Not Only Severe Events: Moderate Dry Periods Impact The Hydraulic Functioning And Survival Of Planted Ponderosa Pine Seedlings, Carolyn R. Koehn, Matthew D. Petrie, Robert M. Hubbard
Not Only Severe Events: Moderate Dry Periods Impact The Hydraulic Functioning And Survival Of Planted Ponderosa Pine Seedlings, Carolyn R. Koehn, Matthew D. Petrie, Robert M. Hubbard
Life Sciences Faculty Research
Juvenile tree survival will increasingly shape the persistence of ponderosa pine forests in the western United States. In contrast to severe pulse disturbances that induce widespread adult and juvenile tree mortality, moderate periods of low rainfall and warm temperatures may reduce forest persistence by killing juvenile trees at the seedling stage. Intensification of these periods in a changing climate could therefore increasingly restrict both natural regeneration and artificial regeneration of planted seedlings. We conducted a controlled field experiment at a single site in the Front Range of Colorado, USA, to determine the responses and survival of 3 Colorado subpopulations of < 1 year old potted ponderosa pines to moderately dry conditions, variation in small rainfall events based on observed patterns, and shaded and unshaded microsite environments. Near surface soil moisture increased slightly following small rainfall events, but declined over the 45-day experimental period. Seedling transpiration and associated canopy cooling declined after ∼13 days, and further declines in transpiration and canopy cooling suggest that the majority of trees in lower rainfall treatments experienced hydraulic dysfunction between days ∼20–30. After 45 days, mortality across all subpopulations and treatments, inferred by relative water loss, exceeded 90–95%. Despite some uncertainty pertaining to the stress tolerance of nursery grown versus naturally germinated conifers, our results show that planted ponderosa pine seedlings < 1 year old are unlikely to survive moderate dry periods of 20+ days relying on small rainfall events. Although microsite conditions and soil moisture availability shaped tree hydraulic functioning early in the experiment (days 1–13), later functioning was shaped predominately by the legacy of rainfall treatments. Our results illustrate the importance of moderate dry events that occur consistently as part of seasonal variation in climate, and show how their intensification may constitute a sustained press that limits opportunities for natural and artificial regeneration.
The Aboveground And Belowground Growth Characteristics Of Juvenile Conifers In The Southwestern United States, N. L. Pirtel, R. M. Hubbard, J. B. Bradford, T. E. Kolb, M. E. Litvak, Scott Abella, S. L. Porter, Matthew Petrie
The Aboveground And Belowground Growth Characteristics Of Juvenile Conifers In The Southwestern United States, N. L. Pirtel, R. M. Hubbard, J. B. Bradford, T. E. Kolb, M. E. Litvak, Scott Abella, S. L. Porter, Matthew Petrie
Life Sciences Faculty Research
Juvenile tree survival will play an important role in the persistence of coniferous forests and woodlands in the southwestern United States (SWUS). Vulnerability to climatic and environmental stress declines as trees grow, such that larger, more deeply rooted juveniles are less likely to experience mortality. It is unclear how juvenile conifers partition the aboveground and belowground components of early growth, if growth differs between species and ecosystem types, and what environmental factors influence juvenile carbon allocation above- or belowground. We developed a novel data set for four juvenile conifer groups (junipers, piñon pines, ponderosa pines, firs; 1121 juveniles sampled, 221 …
Resilience And Alternative Stable States After Desert Wildfires, Scott R. Abella, Dominic M. Gentilcore, Lindsay P. Chiquoine
Resilience And Alternative Stable States After Desert Wildfires, Scott R. Abella, Dominic M. Gentilcore, Lindsay P. Chiquoine
Life Sciences Faculty Research
Improving models of community change is a fundamental goal in ecology and has renewed importance during global change and increasing human disturbance of the biosphere. Using the Mojave Desert (southwestern United States) as a model system, invaded by nonnative plants and subject to wildfire disturbances, we examined models of resilience, alternative stable states, and convergent-divergent trajectories for 36 yr of plant community change after 31 wildfires in communities dominated by the native shrubs Larrea tridentata or Coleogyne ramosissima. Perennial species richness on average was fully resilient within 23 yr after disturbance in both community types. Perennial cover was fully resilient …
Post Burn Restoration Response Of Encelia Virginensis Within A Small Wash System In The Mojave Desert, Dale A. Devitt, Fred Landau, Scott R. Abella, Matt D. Petrie, Ann M. Mcluckie, John O. Kellam
Post Burn Restoration Response Of Encelia Virginensis Within A Small Wash System In The Mojave Desert, Dale A. Devitt, Fred Landau, Scott R. Abella, Matt D. Petrie, Ann M. Mcluckie, John O. Kellam
Life Sciences Faculty Research
Spatial variation in response to restoration treatments within landscapes can be a significant but poorly understood driver of successful ecological restoration. We conducted a field experiment to assess effectiveness of out-planting restoration techniques for the native shrub Encelia virginensis across a soil hydrological gradient. We planted seedlings at five wash locations separated by varying distances based on elevation and percent slope. At each of these plots we planted seedlings, half on the side wall slopes of the wash system and half adjacent to the central wash. Seedlings received either cages, hydrogel, cages and hydrogel, or no treatments. We assessed survival …
Local‐Regional Similarity In Drylands Increases During Multiyear Wet And Dry Periods And In Response To Extreme Events, Matthew D. Petrie, D. P.C. Peters, N. D. Bruss, W. Ji, H. M. Savoy
Local‐Regional Similarity In Drylands Increases During Multiyear Wet And Dry Periods And In Response To Extreme Events, Matthew D. Petrie, D. P.C. Peters, N. D. Bruss, W. Ji, H. M. Savoy
Life Sciences Faculty Research
Climate change is predicted to impact ecosystems through altered precipitation (PPT) regimes. In the Chihuahuan Desert, multiyear wet and dry periods and extreme PPT pulses are the most influential climatic events for vegetation. Vegetation responses are most frequently studied locally, and regional responses are often unclear. We present an approach to quantify correlation of PPT and vegetation responses (as Normalized Difference Vegetation Index [NDVI]) at the Jornada ARS‐LTER site (JRN; 550 km2 area) and the surrounding dryland region (from 0 to 500 km distance; 400,000 km2 study area) as a way to understand regional similarity to locally observed patterns. We …
Persistence And Turnover In Desert Plant Communities During A 37-Yr Period Of Land Use And Climate Change, Scott R. Abella, Ross J. Guida, Chris L. Roberts, Carrie M. Norman, James S. Holland
Persistence And Turnover In Desert Plant Communities During A 37-Yr Period Of Land Use And Climate Change, Scott R. Abella, Ross J. Guida, Chris L. Roberts, Carrie M. Norman, James S. Holland
Life Sciences Faculty Research
Understanding long‐term changes in ecological communities during global change is a priority for 21st‐century ecology. Deserts, already at climatic extremes, are of unique interest because they are projected to be ecosystems most responsive to global change. Within a 500‐km2 landscape in the Mojave Desert, USA, we measured perennial plant communities at 100 sites three times (1979, 2008, and 2016) during 37 yr to evaluate six hypotheses of community change. These hypotheses encompassed shifts in community measures (e.g., diversity, cover) and species elevational distributions, biotic homogenization, disproportionately large change at the highest elevations, relationships between turnover and species’ responses to disturbance …
Cougar Dispersal And Natal Homing In A Desert Environment, David M. Choate, Kathleen M. Longshore, Daniel B. Thompson
Cougar Dispersal And Natal Homing In A Desert Environment, David M. Choate, Kathleen M. Longshore, Daniel B. Thompson
Life Sciences Faculty Research
We present a review of cougar dispersal literature and the first evidence of natural (i.e., unmanipulated) homing behavior by a dispersing male cougar (Puma concolor) that sustained severe injuries crossing the northern Mojave Desert. Based on Global Positioning System and ground tracking data, the male traveled a total distance of 981.1 km at 5.03 km/d, including 170.31 km from the Desert National Wildlife Refuge to the northwestern Grand Canyon, where he sustained severe injuries. The interkill interval increased from 7.1 ± 2.7 d while he was in his natal range to 17.5 ± 4.9 d during dispersal. While homing, the …
Rapidly Restoring Biological Soil Crusts And Ecosystem Functions In A Severely Disturbed Desert Ecosystem, Lindsay P. Chiquoine, Scott R. Abella, Matthew A. Bowker
Rapidly Restoring Biological Soil Crusts And Ecosystem Functions In A Severely Disturbed Desert Ecosystem, Lindsay P. Chiquoine, Scott R. Abella, Matthew A. Bowker
Life Sciences Faculty Research
Restoring biological soil crusts (biocrusts) in degraded drylands can contribute to recovery of ecosystem functions that have global implications, including erosion resistance and nutrient cycling. To examine techniques for restoring biocrusts, we conducted a replicated, factorial experiment on recently abandoned road surfaces by applying biocrust inoculation (salvaged and stored dry for two years), salvaged topsoil, an abiotic soil amendment (wood shavings), and planting of a dominant perennial shrub (Ambrosia dumosa). Eighteen months after treatments, we measured biocrust abundance and species composition, soil chlorophyll a content and fertility, and soil resistance to erosion. Biocrust addition significantly accelerated biocrust recovery on disturbed …
Revegetating Disturbance In National Parks: Reestablishing Native Plants In Saguaro National Park, Sonoran Desert, Scott R. Abella, Kara L. O'Brien, Margaret W. Weesner
Revegetating Disturbance In National Parks: Reestablishing Native Plants In Saguaro National Park, Sonoran Desert, Scott R. Abella, Kara L. O'Brien, Margaret W. Weesner
Life Sciences Faculty Research
No abstract provided.
Consequences Of More Extreme Precipitation Regimes For Terrestrial Ecosystems, S. D. Smith, C. Beier, Aimee T. Classen, Melinda D. Smith, Jana L. Heisler, S. W. Leavitt, Alan K. Knapp, D. Briske, Y. Luo, M. Reichstein, J. E. Bell, Philip A. Fay, R. Sherry, Benjamin Smith
Consequences Of More Extreme Precipitation Regimes For Terrestrial Ecosystems, S. D. Smith, C. Beier, Aimee T. Classen, Melinda D. Smith, Jana L. Heisler, S. W. Leavitt, Alan K. Knapp, D. Briske, Y. Luo, M. Reichstein, J. E. Bell, Philip A. Fay, R. Sherry, Benjamin Smith
Life Sciences Faculty Research
Amplification of the hydrological cycle as a consequence of global warming is forecast to lead to more extreme intra-annual precipitation regimes characterized by larger rainfall events and longer intervals between events. We present a conceptual framework, based on past investigations and ecological theory, for predicting the consequences of this underappreciated aspect of climate change. We consider a broad range of terrestrial ecosystems that vary in their overall water balance. More extreme rainfall regimes are expected to increase the duration and severity of soil water stress in mesic ecosystems as intervals between rainfall events increase. In contrast, xeric ecosystems may exhibit …
Microbial Endemism And Biogeography, Brian P. Hedlund, James T. Staley
Microbial Endemism And Biogeography, Brian P. Hedlund, James T. Staley
Life Sciences Faculty Research
The topic of microbial biogeography is almost 100 years old, however, when confronted with questions about the existence and extent of endemism in the microbial world, many microbiologists respond with opinions and theoretical arguments rather than examples of well-conducted studies. We begin this chapter with an overview of this debate as it applies to free-living prokayotes in part because there are relatively few good microbial biogeography studies. Furthermore, the arguments help to frame microbial biogeography in the larger context of biodiversity in that if endemism is common, then many more species exist.
Arbuscular Mycorrhizae Of Mojave Desert Plants, J. H. Titus, P. J. Titus, R. S. Nowak, S. D. Smith
Arbuscular Mycorrhizae Of Mojave Desert Plants, J. H. Titus, P. J. Titus, R. S. Nowak, S. D. Smith
Life Sciences Faculty Research
Roots of 15 Mojave Desert plant species were assessed for arbuscular mycorrhizal (AM) colonization in spring and autumn 1999. Another 19 species were assessed in autumn only. Perennial species were AM colonized, whereas annual species contained very low levels of AM hyphae or were nonmycorrhizal. The nonnative tree Tamarix ramosissima was also nonmycorrhizal. Levels of hyphae changed over the season in 2 species, arbuscle levels increased in 1 species, and vesicles decreased in 7 species. Mycorrhizal inoculum potential (MIP) was assessed in the soils associated with spring-collected plants. All soils were found to contain MIP. MIP values were not correlated …
Bowen Ratio Estimates Of Evapotranspiration For Stands On The Virgin River In Southern Nevada, Dale A. Devitt, A. Sala, S. D. Smith, J. Cleverly, L. K. Shaulis, R. Hammett
Bowen Ratio Estimates Of Evapotranspiration For Stands On The Virgin River In Southern Nevada, Dale A. Devitt, A. Sala, S. D. Smith, J. Cleverly, L. K. Shaulis, R. Hammett
Life Sciences Faculty Research
A Bowen ratio energy balance was conducted over a Tamarix ramosissima (saltcedar) stand growing in a riparian corridor along the Virgin River in southern Nevada. Measurements in two separate years were compared and contrasted on the basis of changes in growing conditions. In 1994, a drought year, record high temperatures, dry winds, and a falling water table caused partial wilt of outer smaller twigs in the canopy of many trees in the stand around the Bowen tower. Subsequently, evapotranspiration (ET) estimates declined dramatically over a 60‐day period (11 mm d−1 tod−1). In 1995, the Virgin River at the Bowen tower …
Evapotranspiration From A Saltcedar-Dominated Desert Floodplain: A Scaling Approach, S. D. Smith, A. M. Sala, Dale A. Devitt
Evapotranspiration From A Saltcedar-Dominated Desert Floodplain: A Scaling Approach, S. D. Smith, A. M. Sala, Dale A. Devitt
Life Sciences Faculty Research
The purpose of this study was to investigate evapotranspiration (ET) from a variety of scales (leaf to landscape) in saltcedar-dominated floodplain vegetation along the lower Virgin River of southern Nevada. Leaf-level gas exchange indicated that saltcedar exhibits similar stomatal conductance as the sympatric phreatophytes arrowweed, mesquite, and willow. However, sap flow in saltcedar was higher per unit sapwood area than the other species, suggesting that it maintains higher leaf area per unit sapwood area. At the stand level, saltcedar ET was found to exceed potential ET early in the summer when soils were moist and the water table was near …
Structure Of Woody Riparian Vegetation In Great Basin National Park, S. D. Smith, K. J. Murray, F. H. Landau, A. M. Sala
Structure Of Woody Riparian Vegetation In Great Basin National Park, S. D. Smith, K. J. Murray, F. H. Landau, A. M. Sala
Life Sciences Faculty Research
The community composition and population structure of the woody riparian vegetation in Great Basin National Park are described. Community analyses were accomplished by sampling 229 plots along an elevational gradient of 8 major stream systems in the Park. TWINSPAN analysis identified 4 primary species groups that were characterized by Populus tremuloides (aspen), Abies concolor (white fir), Rosa woodsii (Woods rose), and Populus angustifolia (narrowleaf cottonwood) as dominants, respectively. Detrended Correspondence Analysis (DECORANA) showed that the most important environmental factors associated with the distribution of species were elevation and slope, with flood-related physiographic factors having a secondary effect. Analysis of size-class …
Fire In A Riparian Shrub Community: Postburn Water Relations In The Tamarix-Salix Association Along The Lower Colorado River, S. D. Smith, D. E. Busch
Fire In A Riparian Shrub Community: Postburn Water Relations In The Tamarix-Salix Association Along The Lower Colorado River, S. D. Smith, D. E. Busch
Life Sciences Faculty Research
Higher water potentials in recovering burned salt-cedar (Tamarix ramosissima) relative to unburned plants and the opposite situation in willow (Salix gooddingii) provide evidence that postfire water stress is reduced in the former but not the latter. Similarly, diurnal patterns of stomatal conductance in these taxa are consistent with the existence of more vigor in burned salt-cedar than willow. Plots of water potential and transpiration demonstrate that hydraulic efficiencies may contribute to differences in fire recovery.
Riparian Plant Water Relations Along The North Fork Of The Kings River, California, J. L. Nachlinger, S. D. Smith, R. J. Risser
Riparian Plant Water Relations Along The North Fork Of The Kings River, California, J. L. Nachlinger, S. D. Smith, R. J. Risser
Life Sciences Faculty Research
Plant water relations of five obligate ripar-ian species were studied along California's North Fork Kings River. Diurnal stomatal conductance, transpi-ration, and xylem pressure potentials were measured throughout the 1986 growing season and in mid-season in 1987. Patterns were similar for all species although absolute values varied considerably. Maximum stomatal conductance occurred early in the day and season during favorable environmental conditions and decreased as air temperature and the vapor pressure difference between the leaf and air increased. Maximum transpiration rates occurred in mid-morning and mid-summer resulting in estimated daily water losses per unit sunlit leaf area of 163-328 mol H2O …
An Isotopic Analysis Of The Hydrology And Riparian Vegetation Water Sources On Bishop Creek, M. L. Space, J. W. Hess, S. D. Smith
An Isotopic Analysis Of The Hydrology And Riparian Vegetation Water Sources On Bishop Creek, M. L. Space, J. W. Hess, S. D. Smith
Life Sciences Faculty Research
Five power generation plants along an eleven kilometer stretch divert Bishop Creek water for hydro-electric power. Stream diversion may be adversely affecting the riparian vegetation. Stable isotopic analysis is employed to determine surface water/ground-water interactions along the creek. surface water originates primarily from three headwater lakes. Discharge into Bishop Creek below the headwaters is primarily derived from ground water. The average δD and δ18O values are significantly different for surface water and ground water that an isotopic analysis can delineate between these two components of flow. Therefore isotopic shifts along the creek can determine gaining reaches. In addition, by knowing …