Leila Gass
I’m an ecologist and geographer, working with the Western Geographic Science Center.
My primary interest and expertise is in using GIS and remotely-sensed imagery to analyze spatial patterns and relationships on the landscape. Current and previous projects include modeling land cover change and assessing accuracy for the National Land Cover Database (mrlc.gov); producing spatial data for a world-wide assessment of potash resources and for a mineral assessment of the Greater Antilles; and species distribution modeling for desert tortoises.
Science and Products
Madrean Archipelago Ecoregion: Chapter 28 in Status and trends of land change in the Western United States--1973 to 2000
Arizona/New Mexico Plateau Ecoregion: Chapter 26 in Status and trends of land change in the Western United States--1973 to 2000
Arizona/New Mexico Mountains Ecoregion: Chapter 10 in Status and trends of land change in the Western United States--1973 to 2000
Examining wildlife responses to phenology and wildfire using a landscape-scale camera trap network
Plant distributions in the southwestern United States; a scenario assessment of the modern-day and future distribution ranges of 166 Species
Modeling habitat of the desert tortoise (Gopherus agassizii) in the Mojave and parts of the Sonoran Deserts of California, Nevada, Utah, and Arizona
Elevation Derivatives for Mojave Desert Tortoise Habitat
Processed 1938 aerial photography for selected areas of the lower Colorado River, southwestern United States
Spatial and Temporal Patterns of Off-highway Vehicle Use at the Dove Springs OHV Open Area, California. Report prepared for the Bureau of Land Management, California State Office, Sacramento, California
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
- Publications
Filter Total Items: 21
Madrean Archipelago Ecoregion: Chapter 28 in Status and trends of land change in the Western United States--1973 to 2000
The Madrean Archipelago Ecoregion (Omernik, 1987; U.S. Environmental Protection Agency, 1997), also known as the “Madrean Sky Islands” or “Sky Islands,” covers an area of approximately 40,536 km2 (15,651 mi2) in southeastern Arizona and southwestern New Mexico (fig. 1). The ecoregion is bounded on the west by the Sonoran Basin and Range Ecoregion, on the east by the Chihuahuan Deserts Ecoregion, aAuthorsJana Ruhlman, Leila Gass, Barry MiddletonArizona/New Mexico Plateau Ecoregion: Chapter 26 in Status and trends of land change in the Western United States--1973 to 2000
Situated between ecoregions of distinctly different topographies and climates, the Arizona/New Mexico Plateau Ecoregion represents a large area of approximately 192,869 km2 (74,467 mi2) that stretches across northern Arizona, central and northwestern New Mexico, and parts of southwestern Colorado; in addition, a small part extends into southeastern Nevada (fig. 1) (Omernik, 1987; U.S. EnvironmentaAuthorsJana Ruhlman, Leila Gass, Barry MiddletonArizona/New Mexico Mountains Ecoregion: Chapter 10 in Status and trends of land change in the Western United States--1973 to 2000
As the name suggests, the Arizona/New Mexico Mountains Ecoregion includes much of the mountainous regions of these two states, plus a very small part in the Guadalupe Mountains of northwestern Texas. Several isolated areas of higher terrain in Arizona and New Mexico are also included in the ecoregion, which occupies approximately 108,432 km2 (41,866 mi2) (Omernik, 1987; U.S. Environmental ProtectiAuthorsJana Ruhlman, Leila Gass, Barry MiddletonExamining wildlife responses to phenology and wildfire using a landscape-scale camera trap network
Between 2001 and 2009, the Borderlands Jaguar Detection Project deployed 174 camera traps in the mountains of southern Arizona to record jaguar activity. In addition to jaguars, the motion-activated cameras, placed along known wildlife travel routes, recorded occurrences of ~ 20 other animal species. We examined temporal relationships of white-tailed deer (Odocoileus virginianus) and javelina (PecAuthorsMiguel L. Villarreal, Leila Gass, Laura Norman, Joel B. Sankeya, Cynthia S.A. Wallace, Dennis McMacken, Jack L. Childs, Roy E. PetrakisPlant distributions in the southwestern United States; a scenario assessment of the modern-day and future distribution ranges of 166 Species
The authors developed spatial models of the predicted modern-day suitable habitat (SH) of 166 dominant and indicator plant species of the southwestern United States (herein referred to as the Southwest) and then conducted a coarse assessment of potential future changes in the distribution of their suitable habitat under three climate-change scenarios for two time periods. We used Maxent-based spatAuthorsKathryn A. Thomas, Patricia P. Guertin, Leila GassModeling habitat of the desert tortoise (Gopherus agassizii) in the Mojave and parts of the Sonoran Deserts of California, Nevada, Utah, and Arizona
Habitat modeling is an important tool used to simulate the potential distribution of a species for a variety of basic and applied questions. The desert tortoise (Gopherus agassizii) is a federally listed threatened species in the Mojave Desert and parts of the Sonoran Desert of California, Nevada, Utah, and Arizona. Land managers in this region require reliable information about the potential distAuthorsKenneth E. Nussear, Todd C. Esque, Richard D. Inman, Leila Gass, Kathryn A. Thomas, Cynthia S.A. Wallace, Joan B. Blainey, David M. Miller, Robert H. WebbElevation Derivatives for Mojave Desert Tortoise Habitat
This report describes the methods used to derive various elevation-derivative grids that were inputted to the Mojave Desert Tortoise Habitat model (L. Gass and others, unpub. data). These grids, which capture information on surface roughness and topographic characteristics, are a subset of the environmental datasets evaluated for the tortoise habitat model. This habitat model is of major importancAuthorsCynthia S.A. Wallace, Leila GassProcessed 1938 aerial photography for selected areas of the lower Colorado River, southwestern United States
The U.S. Geological Survey (USGS) initiated a study of the Lower Colorado River to derive temporal-change characteristics from the predam period to the present. In this report, we present summary information on accomplishments under a USGS task for the Department of the Interior's Landscapes in the West project. We discuss our preliminary results in compiling a digital database of geospatial inforAuthorsLaura M. Norman, Michael Gishey, Leila Gass, Brian Yanites, Edwin Pfeifer, Ron Simms, Ray AhlbrandtSpatial and Temporal Patterns of Off-highway Vehicle Use at the Dove Springs OHV Open Area, California. Report prepared for the Bureau of Land Management, California State Office, Sacramento, California
No abstract available at this timeAuthorsJ.R. Matchett, L. Gass, M.L. Brooks, A.M. Mathie, R.D. Vitales, M.W. Campagna, D. M. Miller, J.F. WeigandNon-USGS Publications**
Higgins, L.V. and L. Gass. 1993. Birth to weaning: parturition, duration of lactation, and attendance cycles of Australian sea lions (Neophoca cinerea). Canadian Journal of Zoology 71(10):2047-2055.Morris, M.R., L. Gass, and M.J. Ryan. 1995. Assessment and individual recognition of opponents in the pygmy swordtails Xiphophorus nigrensis and X. multilineatus. Behavioral Ecology and Sociobiology 37:303-310.Gass, L. 1996. Nesting behavior of Golden-cheeked Warblers in Travis County, Texas. MA thesis, Southwest Texas State University.Gass, L. and P.W. Barnes. 1998. Microclimate and understory structure of live oak (Quercus fusiformis) clusters in central Texas, USA. Southwestern Naturalist 43: 183-194.Ladd, C. and L. Gass. 1999. Golden-cheeked Warbler (Dendroica chrysoparia). In The Birds of North America (A. Poole and F. Gill, Eds.). The Academy of Natural Sciences, Philadelphia, and The American Ornithologists’ Union, Washington, D.C.**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.