• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 35
  • Tagged with
  • 35
  • 35
  • 35
  • 34
  • 20
  • 12
  • 8
  • 7
  • 6
  • 6
  • 3
  • 3
  • 3
  • 3
  • 3
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Differential Response of Native Arizona Gray Squirrels and Introduced Abert's Squirrels to a Mosaic of Burn Severities in the Santa Catalina Mountains

Ketcham, Shari Lynn January 2015 (has links)
Disturbance events can alter habitat properties, leading to species displacement, isolation and/or local extinction. In addition, introduced species have been recognized as a threat to biodiversity of native species. Understanding the interacting impacts of fire on native and introduced wildlife species, and the influence on a native species of competition with an introduced species after ecosystem change is critical. Tree squirrels are indicators of forest health; we used two species to determine thresholds and assess behavioral responses to determine adaption to habitat alterations. We studied native Arizona gray squirrels (Sciurus arizonensis), which are believed to favor riparian habitat, and introduced Abert's squirrels (S. aberti), which prefer open parklike ponderosa pine (Pinus ponderosa) in the Santa Catalina Mountains, Arizona, USA. We examined how native but reportedly declining Arizona gray squirrels and introduced Abert's squirrels use areas within widespread fires that burned the study area in 2002-3. Fires burned in a mosaic pattern of unburned, low, moderate, and high burn severity patches. To determine how fire may affect squirrel habitat and behavior, we examined how fire altered habitat use and occupancy, and used distance sampling to determine squirrel abundance, distribution and use within a mosaic of burn severities. Occupancy and habitat use indicate that introduced Abert's squirrels are better adapted to post-fire conditions whereas native Arizona gray squirrels may be adversely impacted by fire disturbance. Our results suggest that Arizona gray squirrel populations may be locally imperiled due to post-fire habitat alteration and loss exacerbated by competition with Abert's squirrels. Abert's squirrels predominantly occupied unburned ponderosa pine and mixed conifer zones with open understories. In contrast, Arizona gray squirrels were documented at only four sites and primarily occupied unburned to low burn riparian areas with dense understories. Abert's squirrels predominately nest and feed in unburned coniferous areas whereas Arizona gray squirrels nest in unburned to low burn nonconiferous areas. Arizona gray squirrels have a reduced distribution and potentially in decline but only remain at lower elevations on the Santa Catalina Mountains. Fire management and restoration efforts should include examination of the differential impacts of fire on native and invasive species.
32

BIOLOGY OF SPARASSIS RADICATA (WEIR) IN SOUTHERN ARIZONA

Martin, Kenneth J., 1942- January 1974 (has links)
No description available.
33

The breeding biology of the red-faced warbler (Cardellina rubrifrons)

Bulmer, Walter, 1942- January 1966 (has links)
No description available.
34

The Catalina recreational area highway

Hampshire, Claude Carlyle, 1894-, Hampshire, Claude Carlyle, 1894- January 1933 (has links)
No description available.
35

Migration of Recharge Water Downgradient from the Santa Catalina Mountains into the Tucson Basin Aquifer

Barger, Erin E. January 1996 (has links)
Aquifers in the arid alluvial basins of the southwestern U.S. are recharged predominantly by infiltration from streams within the basins and by water entering along the margins of the basins from surrounding mountains (mountain -front recharge). The Tucson Basin of Southeastern Arizona is such a basin. The Santa Catalina Mountains form the northern boundary of this basin and receive more than twice as much precipitation (about 70 cm/yr) as the basin does (about 30 cm/yr). In this study environmental isotopes were employed to investigate the migration of precipitation basinward through joints and fractures. Water samples were obtained from springs in the Santa Catalina Mountains. Stable isotopes and thermonuclear bomb-produced tritium enabled qualitative characterizations of flow paths and flow velocities. Stable isotopic measurements fail to display a direct altitude effect. Tritium values indicate that although a few springs discharge pre-bomb water, most springs discharge waters from the 1960's or later.

Page generated in 0.046 seconds