WHAT THE AMAGMATIC CORRIDOR IN THE CENTRAL BASIN AND RANGE REVEALS ABOUT THE RELATIONSHIP BETWEEN MAGMATISM AND REGIONAL NEOGENE EXTENSION

The relationship between spatial patterns in the physical environment and patterns in community and trophic structure in the benthic fauna was investigated in an estuary with periodic deoxygenation of the near- bottom water. Six sites were sampled between intertidal mangroves and an 8 m deep basin of Port Hacking, N.S.W. A total of 163 species was collected, ranging from 11 to 94 at each site. Both frequency and biomass were least in the central basin and highest in a bed of the seagrass Zostera capricorni Aschers. The abundances at these sites encompass the range of values previously recorded for estuaries on the east coast of Australia. The dominant species differed from those reported from other New South Wales estuaries, although the same species were usually present. The distribution of common species was limited by fluctuations in dissolved oxygen levels, but not obviously so by sediment differences or short-term fluctuations in water temperature or salinity. Frequency-based diversity and evenness values were similar to those from other estuarine areas. Biomass-based values were lower at most sites than frequency-based values. Patterns of diversity and evenness could not be simply interpreted as indicators of environmental harshness in the community.

Download Full-text

Timing and synchrony of births in bighorn sheep: implications for reintroduction and conservation

Wildlife Research ◽

10.1071/wr12059 ◽

2012 ◽

Vol 39 (7) ◽

pp. 565 ◽

Cited By ~ 17

Author(s):

Jericho C. Whiting ◽

Daniel D. Olson ◽

Justin M. Shannon ◽

R. Terry Bowyer ◽

Robert W. Klaver ◽

...

Keyword(s):

Life History ◽

Environmental Conditions ◽

Release Site ◽

Source Area ◽

Bighorn Sheep ◽

Basin And Range ◽

Central Basin ◽

Uinta Mountains ◽

Life History Characteristics ◽

Normalised Difference Vegetation Index

Context Timing (mean birthdate) and synchrony (variance around that date) of births can influence survival of young and growth in ungulate populations. Some restored populations of ungulates may not adjust these life-history characteristics to environments of release sites until several years after release, which may influence success of reintroductions. Aims We quantified timing and synchrony of births from 2005 to 2007 in four populations of reintroduced bighorn sheep (Ovis canadensis) occupying two ecoregions (Central Basin and Range and Wasatch and Uinta Mountains) in Utah, USA, to investigate whether bighorns would adjust these life-history characteristics to environmental conditions of the two ecoregions. We also compared timing and synchrony of births for bighorns in their source herd (Antelope Island) with bighorns in an ecologically similar release site (Stansbury Mountains) during 2006 and 2007. Methods We relocated female bighorns to record birthdates of young, and observed groups of collared bighorns to quantify use of elevation by those ungulates. We also calculated the initiation, rate and timing of peak green-up by ecoregion, using the normalised difference vegetation index. Key results We quantified 274 birthdates, and although only separated by 57 km, bighorn populations occupying the Central Basin and Range Mountains gave birth an average of 29 days earlier than did those on the Wasatch and Uinta Mountains, which corresponded with the initiation of vegetation green-up. Additionally, bighorn sheep on the Stansbury Mountains (ecologically similar release site) gave birth at similar times as did bighorns on Antelope Island (source area). Conclusions Populations of bighorn sheep that were reintroduced into adjacent ecoregions adjusted timing of births to environments and green-up of vegetation in restoration areas. Timing and synchrony of births for reintroduced bighorn sheep in an ecologically similar release site were the same as those of their source area. Implications Consideration should be given to the adjustment of timing and synchrony of births when reintroducing bighorns, especially when animals are released into different ecoregions. Also, biologists should select release sites that are ecologically similar to source areas, thereby reducing potential negative effects of animals adjusting timing and synchrony of births to environmental conditions of restoration areas.

Download Full-text

Contemporary vertical velocity of the central Basin and Range and uplift of the southern Sierra Nevada

Geophysical Research Letters ◽

10.1029/2008gl034949 ◽

2008 ◽

Vol 35 (20) ◽

Cited By ~ 13

Author(s):

Noah P. Fay ◽

Richard A. Bennett ◽

Sigrún Hreinsdóttir

Keyword(s):

Sierra Nevada ◽

Vertical Velocity ◽

Basin And Range ◽

Central Basin

Download Full-text

Stratigraphy of the Eocene–Oligocene Titus Canyon Formation, Death Valley, California, and Eocene extensional tectonism in the Basin and Range

Geosphere ◽

10.1130/ges02363.1 ◽

2021 ◽

Author(s):

Nikolas Midttun ◽

Nathan A. Niemi ◽

Bianca Gallina

Keyword(s):

Detrital Zircon ◽

Convergence Rates ◽

Plate Boundary ◽

Basin And Range ◽

Late Eocene ◽

Death Valley ◽

Central Basin ◽

Geologic Mapping ◽

Extensional Basin ◽

Stress Changes

Geologic mapping, measured sections, and geochronologic data elucidate the tectono-stratigraphic development of the Titus Canyon extensional basin in Death Valley, California, and provide new constraints on the age of the Titus Canyon Formation, one of the earliest syn-extensional deposits in the central Basin and Range. Detrital zircon maximum depositional ages (MDAs) and compiled 40Ar/39Ar ages indicate that the Titus Canyon Formation spans 40(?)–30 Ma, consistent with an inferred Duchesnean age for a unique assemblage of mammalian fossils in the lower part of the formation. The Titus Canyon Formation preserves a shift in depositional environment from fluvial to lacustrine at ca. 35 Ma, which along with a change in detrital zircon provenance may reflect both the onset of local extensional tectonism and climatic changes at the Eocene–Oligocene boundary. Our data establish the Titus Canyon basin as the southernmost basin in a system of late Eocene extensional basins that formed along the axis of the Sevier orogenic belt. The distribution of lacustrine deposits in these Eocene basins defines the extent of a low-relief orogenic plateau (Nevadaplano) that occupied eastern Nevada at least through Eocene time. As such, the age and character of Titus Canyon Formation implies that the Nevadaplano extended into the central Basin and Range, ~200 km farther south than previously recognized. Development of the Titus Canyon extensional basin precedes local Farallon slab removal by ca. 20 Ma, implying that other mechanisms, such as plate boundary stress changes due to decreased convergence rates in Eocene time, are a more likely trigger for early extension in the central Basin and Range.

Download Full-text

Conservation of Kit Foxes in the Great Basin Desert: Review and Recommendations

Journal of Fish and Wildlife Management ◽

10.3996/jfwm-20-025 ◽

2020 ◽

Vol 11 (2) ◽

pp. 679-698

Author(s):

Robert C. Lonsinger ◽

Bryan M. Kluever ◽

Lucas K. Hall ◽

Randy T. Larsen ◽

Eric M. Gese ◽

...

Keyword(s):

Great Basin ◽

Management Practices ◽

Population Change ◽

Basin And Range ◽

Population Connectivity ◽

Sensitivity Analyses ◽

Central Basin ◽

Great Basin Desert ◽

Kit Fox ◽

Resource Managers

Abstract The kit fox Vulpes macrotis is a species of concern to land managers in the Great Basin Desert of North America. Once common, kit foxes have declined from historical levels. Research on kit foxes in western Utah has spanned nearly 70 y and has potential to inform management and conservation within the Central Basin and Range Ecoregion of the Great Basin Desert. We conducted a systematic literature review on the northern kit fox subspecies V. m. nevadensis. We focused on studies conducted in the Central Basin and Range Ecoregion, which represents the majority of the Great Basin Desert, and provided a comprehensive summary of their ecology and demographics for resource managers. To guide future monitoring, we also reviewed techniques used for kit fox monitoring and research, and evaluated the strengths, limitations, and advances of these techniques. We identified four key factors that deserve consideration when selecting monitoring techniques for kit foxes: estimable parameters, reliability, cost, and rate of data return. Finally, we identify four primary management recommendations. We recommend that managers (1) expand kit fox monitoring and population assessments more broadly across the Great Basin Desert. To ensure future monitoring meets the needs of resource managers, we recommend (2) the application of a structured decision-making process to identify key parameters and approaches. To better understand the factors limiting kit fox populations we recommend (3) population viability and parameter sensitivity analyses to identify drivers of population change. Finally, based on evidence that genetic diversity of kit fox populations has been maintained by undescribed patterns of gene flow, we recommend (4) a broad-scale assessment of population connectivity to identify corridors supporting metapopulation dynamics. These recommendations will facilitate proactive conservation of kit foxes and management practices to reduce future population declines.

Download Full-text