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
Filter Total Items: 21
Thematic accuracy assessment of the NLCD 2019 land cover for the conterminous United States
The National Land Cover Database (NLCD), a product suite produced through the MultiResolution Land Characteristics (MRLC) consortium, is an operational land cover monitoring program. Starting from a base year of 2001, NLCD releases a land cover database every 2–3-years. The recent release of NLCD2019 extends the database to 18 years. We implemented a stratified random sample to collect land cover
National Land Cover Database 2019: A comprehensive strategy for creating the 1986-2019 forest disturbance product
The National Land Cover Database (NLCD) 2016 products show that, between 2001 and 2016, nearly half of the land cover change in the conterminous United States (CONUS) involved forested areas. To ensure the quality of NLCD land cover and land cover change products, it is important to accurately detect the location and time of forest disturbance. We designed a comprehensive strategy to integrate a c
Conterminous United States land cover change patterns 2001–2016 from the 2016 National Land Cover Database
The 2016 National Land Cover Database (NLCD) product suite (available on www.mrlc.gov), includes Landsat-based, 30 m resolution products over the conterminous (CONUS) United States (U.S.) for land cover, urban imperviousness, and tree, shrub, herbaceous and bare ground fractional percentages. The release of NLCD 2016 provides important new information on land change patterns across CONUS from 2001
Modeling 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 dist
A new generation of the United States National Land Cover Database: Requirements, research priorities, design, and implementation strategies
The U.S. Geological Survey (USGS), in partnership with several federal agencies, has developed and released four National Land Cover Database (NLCD) products over the past two decades: NLCD 1992, 2001, 2006, and 2011. These products provide spatially explicit and reliable information on the Nation’s land cover and land cover change. To continue the legacy of NLCD and further establish a long-term
Preliminary assessment of porphyry copper deposits in the Sierra Maestra, Cuba
The U.S. Geological Survey’s “three-step” form of mineral-resource assessment was used to obtain a preliminary estimate of copper resources in undiscovered porphyry deposits of the Paleogene Sierra Maestra Arc. Results of this preliminary assessment suggest that a mean of 3.2 undiscovered deposits are likely present. This estimate is comparable to results from an independently-derived porphyry dep
Methods for converting continuous shrubland ecosystem component values to thematic National Land Cover Database classes
The National Land Cover Database (NLCD) provides thematic land cover and land cover change data at 30-meter spatial resolution for the United States. Although the NLCD is considered to be the leading thematic land cover/land use product and overall classification accuracy across the NLCD is high, performance and consistency in the vast shrub and grasslands of the Western United States is lower tha
Thematic accuracy assessment of the 2011 National Land Cover Database (NLCD)
Accuracy assessment is a standard protocol of National Land Cover Database (NLCD) mapping. Here we report agreement statistics between map and reference labels for NLCD 2011, which includes land cover for ca. 2001, ca. 2006, and ca. 2011. The two main objectives were assessment of agreement between map and reference labels for the three, single-date NLCD land cover products at Level II and Level I
Comparison of remote sensing indices for monitoring of desert cienegas
This research considers the applicability of different vegetation indices at 30 m resolution for mapping and monitoring desert wetland (cienega) health and spatial extent through time at Cienega Creek in southeastern Arizona, USA. Multiple stressors including the risk of decadal-scale drought, the effects of current and predicted global warming, and continued anthropogenic pressures threaten aquat
Potash: a global overview of evaporate-related potash resources, including spatial databases of deposits, occurrences, and permissive tracts
Potash is mined worldwide to provide potassium, an essential nutrient for food crops. Evaporite-hosted potash deposits are the largest source of salts that contain potassium in water-soluble form, including potassium chloride, potassium-magnesium chloride, potassium sulfate, and potassium nitrate. Thick sections of evaporitic salt that form laterally continuous strata in sedimentary evaporite basi
Remote sensing analysis of riparian vegetation response to desert marsh restoration in the Mexican Highlands
Desert marshes, or cienegas, are extremely biodiverse habitats imperiled by anthropogenic demands for water and changing climates. Given their widespread loss and increased recognition, remarkably little is known about restoration techniques. In this study, we examine the effects of gabions (wire baskets filled with rocks used as dams) on vegetation in the Cienega San Bernardino, in the Arizona, S
Accuracy assessment of NLCD 2006 land cover and impervious surface
Release of NLCD 2006 provides the first wall-to-wall land-cover change database for the conterminous United States from Landsat Thematic Mapper (TM) data. Accuracy assessment of NLCD 2006 focused on four primary products: 2001 land cover, 2006 land cover, land-cover change between 2001 and 2006, and impervious surface change between 2001 and 2006. The accuracy assessment was conducted by selecting
Non-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.
Science and Products
- Publications
Filter Total Items: 21
Thematic accuracy assessment of the NLCD 2019 land cover for the conterminous United States
The National Land Cover Database (NLCD), a product suite produced through the MultiResolution Land Characteristics (MRLC) consortium, is an operational land cover monitoring program. Starting from a base year of 2001, NLCD releases a land cover database every 2–3-years. The recent release of NLCD2019 extends the database to 18 years. We implemented a stratified random sample to collect land coverNational Land Cover Database 2019: A comprehensive strategy for creating the 1986-2019 forest disturbance product
The National Land Cover Database (NLCD) 2016 products show that, between 2001 and 2016, nearly half of the land cover change in the conterminous United States (CONUS) involved forested areas. To ensure the quality of NLCD land cover and land cover change products, it is important to accurately detect the location and time of forest disturbance. We designed a comprehensive strategy to integrate a cConterminous United States land cover change patterns 2001–2016 from the 2016 National Land Cover Database
The 2016 National Land Cover Database (NLCD) product suite (available on www.mrlc.gov), includes Landsat-based, 30 m resolution products over the conterminous (CONUS) United States (U.S.) for land cover, urban imperviousness, and tree, shrub, herbaceous and bare ground fractional percentages. The release of NLCD 2016 provides important new information on land change patterns across CONUS from 2001Modeling 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 distA new generation of the United States National Land Cover Database: Requirements, research priorities, design, and implementation strategies
The U.S. Geological Survey (USGS), in partnership with several federal agencies, has developed and released four National Land Cover Database (NLCD) products over the past two decades: NLCD 1992, 2001, 2006, and 2011. These products provide spatially explicit and reliable information on the Nation’s land cover and land cover change. To continue the legacy of NLCD and further establish a long-termPreliminary assessment of porphyry copper deposits in the Sierra Maestra, Cuba
The U.S. Geological Survey’s “three-step” form of mineral-resource assessment was used to obtain a preliminary estimate of copper resources in undiscovered porphyry deposits of the Paleogene Sierra Maestra Arc. Results of this preliminary assessment suggest that a mean of 3.2 undiscovered deposits are likely present. This estimate is comparable to results from an independently-derived porphyry depMethods for converting continuous shrubland ecosystem component values to thematic National Land Cover Database classes
The National Land Cover Database (NLCD) provides thematic land cover and land cover change data at 30-meter spatial resolution for the United States. Although the NLCD is considered to be the leading thematic land cover/land use product and overall classification accuracy across the NLCD is high, performance and consistency in the vast shrub and grasslands of the Western United States is lower thaThematic accuracy assessment of the 2011 National Land Cover Database (NLCD)
Accuracy assessment is a standard protocol of National Land Cover Database (NLCD) mapping. Here we report agreement statistics between map and reference labels for NLCD 2011, which includes land cover for ca. 2001, ca. 2006, and ca. 2011. The two main objectives were assessment of agreement between map and reference labels for the three, single-date NLCD land cover products at Level II and Level IComparison of remote sensing indices for monitoring of desert cienegas
This research considers the applicability of different vegetation indices at 30 m resolution for mapping and monitoring desert wetland (cienega) health and spatial extent through time at Cienega Creek in southeastern Arizona, USA. Multiple stressors including the risk of decadal-scale drought, the effects of current and predicted global warming, and continued anthropogenic pressures threaten aquatPotash: a global overview of evaporate-related potash resources, including spatial databases of deposits, occurrences, and permissive tracts
Potash is mined worldwide to provide potassium, an essential nutrient for food crops. Evaporite-hosted potash deposits are the largest source of salts that contain potassium in water-soluble form, including potassium chloride, potassium-magnesium chloride, potassium sulfate, and potassium nitrate. Thick sections of evaporitic salt that form laterally continuous strata in sedimentary evaporite basiRemote sensing analysis of riparian vegetation response to desert marsh restoration in the Mexican Highlands
Desert marshes, or cienegas, are extremely biodiverse habitats imperiled by anthropogenic demands for water and changing climates. Given their widespread loss and increased recognition, remarkably little is known about restoration techniques. In this study, we examine the effects of gabions (wire baskets filled with rocks used as dams) on vegetation in the Cienega San Bernardino, in the Arizona, SAccuracy assessment of NLCD 2006 land cover and impervious surface
Release of NLCD 2006 provides the first wall-to-wall land-cover change database for the conterminous United States from Landsat Thematic Mapper (TM) data. Accuracy assessment of NLCD 2006 focused on four primary products: 2001 land cover, 2006 land cover, land-cover change between 2001 and 2006, and impervious surface change between 2001 and 2006. The accuracy assessment was conducted by selectingNon-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.