scholarly journals Temporal partitioning and the effects of climate change on two ecologically similar desert bats

2018 ◽  
Vol 99 (6) ◽  
pp. 1486-1494
Author(s):  
Connor T Lambert ◽  
Lucas K Hall ◽  
Randy T Larsen ◽  
Robert N Knight ◽  
Brock R McMillan
Keyword(s):  
Climate Change ◽  
Surface Area ◽  
Mojave Desert ◽  
Free Water ◽  
Limited Resource ◽  
Water Sources ◽  
American Southwest ◽  
Temporal Partitioning ◽  
Bat Activity ◽  
Drinking Behaviors

Abstract Climate change is predicted to create increasingly arid deserts with fewer and smaller water sources. Because free water is already limiting for arid-adapted animals, reductions in water likely will impact desert species and how they compete for this limited resource. Our objective was to examine how the size of water sources influenced competition between 2 ecologically similar bats, Parastrellus hesperus and Myotis californicus, in the American Southwest. Bats are a highly successful taxon in deserts, although many rely upon access to free water. We examined bat activity observationally over 35 different-sized water sources throughout the Mojave Desert in southwestern Utah, United States, and experimentally reduced the surface area of 2 water sources. Parastrellus hesperus and M. californicus typically occurred at the same water sources, but both species temporally partitioned their use of shared water sources regardless of the surface area of the water. Experimentally reducing surface area of water sources negatively affected drinking behaviors of both species and resulted in higher overall activity, but temporal partitioning still occurred. While loss of water may influence some competitive interactions, mechanisms such as temporal partitioning can potentially allow continued co-use of limited resources by competing species.

Water scarcity and sustainability in the arid area of North America: Insights gained from a cross border perspective

2017 ◽  
Vol 7 (1) ◽  
pp. 6-18 ◽  
Author(s):  
Alejandro Yáñez-Arancibia ◽  
John W. Day
Keyword(s):  
Climate Change ◽  
North America ◽  
Water Scarcity ◽  
Economic Change ◽  
American Southwest ◽  
Arid Area ◽  
Border Region ◽  
Cross Border ◽  
Sharp Focus ◽  
The Face

The arid border region that encompasses the American Southwest and the Mexican northwest is an area where the nexus of water scarcity and climate change in the face of growing human demands for water, emerging energy scarcity, and economic change comes into sharp focus.

Oxygen isotopes in terrestrial gastropod shells track Quaternary climate change in the American Southwest

2021 ◽  
pp. 1-11
Author(s):  
Jason A. Rech ◽  
Jeffrey S. Pigati ◽  
Kathleen B. Springer ◽  
Stephanie Bosch ◽  
Jeffrey C. Nekola ◽  
...  
Keyword(s):  
Climate Change ◽  
Oxygen Isotopic Composition ◽  
American Southwest ◽  
Quaternary Climate ◽  
San Pedro ◽  
Spatial Coverage ◽  
Oxygen Isotopic ◽  
The Last Glacial Maximum ◽  
The Last Glacial ◽  
Terrestrial Gastropod

Abstract Recent studies have shown the oxygen isotopic composition (δ18O) of modern terrestrial gastropod shells is determined largely by the δ18O of precipitation. This implies that fossil shells could be used to reconstruct the δ18O of paleo-precipitation as long as the isotopic system, including the hydrologic pathways of the local watershed and the gastropod systematics, is well understood. In this study, we measured the δ18O values of 456 individual gastropod shells collected from paleowetland deposits in the San Pedro Valley, Arizona that range in age from ca. 29.1 to 9.8 ka. Isotopic differences of up to 2‰ were identified among the four taxa analyzed (Succineidae, Pupilla hebes, Gastrocopta tappaniana, and Vallonia gracilicosta), with Succineidae shells yielding the highest values and V. gracilicosta shells exhibiting the lowest values. We used these data to construct a composite isotopic record that incorporates these taxonomic offsets, and found shell δ18O values increased by ~4‰ between the last glacial maximum and early Holocene, which is similar to the magnitude, direction, and rate of isotopic change recorded by speleothems in the region. These results suggest the terrestrial gastropods analyzed here may be used as a proxy for past climate in a manner that is complementary to speleothems, but potentially with much greater spatial coverage.

Exposure to climate change drives stability or collapse of desert mammal and bird communities

Science ◽  
2021 ◽  
Vol 371 (6529) ◽  
pp. 633-636 ◽  
Author(s):  
E. A. Riddell ◽  
K. J. Iknayan ◽  
L. Hargrove ◽  
S. Tremor ◽  
J. L. Patton ◽  
...  
Keyword(s):  
Climate Change ◽  
Heat Flux ◽  
Small Mammal ◽  
Mojave Desert ◽  
Bird Communities ◽  
Climate Projections ◽  
Microhabitat Use ◽  
High Exposure ◽  
Species Occupancy ◽  
Mammal Communities

High exposure to warming from climate change is expected to threaten biodiversity by pushing many species toward extinction. Such exposure is often assessed for all taxa at a location from climate projections, yet species have diverse strategies for buffering against temperature extremes. We compared changes in species occupancy and site-level richness of small mammal and bird communities in protected areas of the Mojave Desert using surveys spanning a century. Small mammal communities remained remarkably stable, whereas birds declined markedly in response to warming and drying. Simulations of heat flux identified different exposure to warming for birds and mammals, which we attribute to microhabitat use. Estimates from climate projections are unlikely to accurately reflect species’ exposure without accounting for the effects of microhabitat buffering on heat flux.

scholarly journals Summer Watering Patterns of Mule Deer in the Great Basin Desert, USA: Implications of Differential Use by Individuals and the Sexes for Management of Water Resources

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Andrew V. Shields ◽  
Randy T. Larsen ◽  
Jericho C. Whiting
Keyword(s):  
Water Resources ◽  
Great Basin ◽  
Mule Deer ◽  
Free Water ◽  
Water Sources ◽  
Limiting Factor ◽  
Mountain Range ◽  
Great Basin Desert ◽  
Water Developments ◽  
Conservation And Management

Changes in the abundance and distribution of free water can negatively influence wildlife in arid regions. Free water is considered a limiting factor for mule deer (Odocoileus hemionus) in the Great Basin Desert. Consequently, a better understanding of differential use of water by individuals and the sexes could influence the conservation and management of mule deer and water resources in their habitats. We deployed remote cameras at all known water sources (13 wildlife water developments and 4 springs) on one mountain range in western Utah, USA, during summer from 2007 to 2011 to document frequency and timing of water use, number of water sources used by males and females, and to estimate population size from individually identified mule deer. Male and female mule deer used different water sources but visited that resource at similar frequencies. Individual mule deer used few water sources and exhibited high fidelity to that resource. Wildlife water developments were frequently used by both sexes. Our results highlight the differing use of water sources by sexes and individual mule deer. This information will help guide managers when siting and reprovisioning wildlife water developments meant to benefit mule deer and will contribute to the conservation and management of this species.

scholarly journals Natural resource mitigation, adaptation and research needs related to climate change in the Great Basin and Mojave Desert

2011 ◽  
pp. i-34 ◽  
Author(s):  
Debra L. Hughson ◽  
David E. Busch ◽  
Scott Davis ◽  
Sean P. Finn ◽  
Steve Caicco ◽  
...  
Keyword(s):  
Climate Change ◽  
Great Basin ◽  
Natural Resource ◽  
Mojave Desert ◽  
Research Needs

Characterization of thin water layers in pulp by tritium exchange. Part 1: Methods development

Holzforschung ◽  
2007 ◽  
Vol 61 (2) ◽  
pp. 115-119 ◽  
Author(s):  
Frances L. Walsh ◽  
Sujit Banerjee
Keyword(s):  
Water Content ◽  
Surface Area ◽  
Tritiated Water ◽  
Bound Water ◽  
Free Water ◽  
Fiber Surface ◽  
Bulk Water ◽  
Methods Development ◽  
A Value ◽  
A New Technique

Abstract A new technique for measuring the monolayer water content of fiber is presented. Tritiated water is added to a pulp/water suspension, whereupon the tritium partitions between the bulk water and the pulp. In the pulp phase the tritium can exchange with free water, bound water, and with hydroxyl and other protons present in the pulp matrix. The free water in the pulp is then removed by displacement with acetone. The tritium remaining in the pulp is mostly associated with tightly bound water, with a small fraction being tied up with the exchangeable hydrogen in pulp. The procedure provides a value of 10% for the tightly bound water content of hardwood or softwood fiber, either bleached or unbleached. If this water is assumed to cover the fiber surface as a monolayer, then an estimate of the wet surface area of the fiber can be obtained. This estimate compares well with independent measurements of surface area.

Behavior of Depressurization in Type III Hydrate Reservoirs

SPE Journal ◽  
2013 ◽  
Vol 19 (02) ◽  
pp. 191-205 ◽  
Author(s):  
A.. Shahbazi ◽  
M.. Pooladi-Darvish
Keyword(s):  
Surface Area ◽  
Similarity Solution ◽  
Traveling Wave ◽  
Wave Solution ◽  
Free Water ◽  
Similarity Solutions ◽  
Traveling Wave Solution ◽  
Type I ◽  
Type Iii ◽  
Hydrate Reservoirs

Summary Hydrate reservoirs have been categorized as Types I, II, and III: Type I has underlying free gas, Type II has underlying free water, and Type III is sandwiched by impermeable formations (i.e., there is no underlying mobile phase beneath the hydrate layer). The updip portion of the Mount Elbert prospect in Alaska is one example of a Type III hydrate reservoir. Depressurization in Type III reservoirs is characterized by difficulty in reducing pressure over a large region because of limited available surface area for decomposition and low permeability in the hydrate. This is unlike the case in Type I and II reservoirs, where pressure could be reduced across a large surface area between the hydrate and the underlying free phase. A 3D numerical model incorporating heat and fluid flow, along with kinetics of decomposition and (re)formation of hydrate and ice, is developed in this paper. Next, the solution behavior of Type III hydrate reservoirs in response to application of the depressurization technique is studied, with the goal of understanding the interactions between fluid and heat flow and their effects on the decomposition region. This is achieved by exploring for 1D similarity solutions in Type III reservoirs. (A similarity solution of a PDE is a solution that depends on one variable which itself is made up of the individual independent variables that the PDE depended on.) The results of this study indicate that the behavior of Type III reservoirs is sometimes close to that of diffusion problems, suggesting that a similarity solution exists. This has also been shown to be the case in the literature. However, under some other conditions, for the first time it is shown that the solution to this problem is also identical to a traveling-wave solution, which could offer another type of similarity solution often observed in diffusive/reactive problems that exhibit frontal behavior and sharp gradients. (The traveling-wave solution or convective similarity solution is a type of similarity solution in which the similarity variable is x−vt, with v being the constant characteristic speed. This type of solution exists for the problems in which the profiles of the dependent variables, such as pressure or saturation, advance in time in the form of traveling waves without changing shape and velocity.) Conditions leading to development of these two types of similarity solutions are identified. The contribution of this work is in identifying the different solution regimes in Type III hydrate reservoirs. This improved understanding could lead to simplifying the modeling of the nonlinear mechanisms involved in the process of gas production from hydrates.

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