- Geospatial Consulting @ UC Davis
Dept. of Environmental Science & Policy
University of California, Davis
One Shields Avenue
Davis, CA 95616
- Geography, Biogeography, Geomorphology, Physical Geography, Coastal Geomorphology, Coastal Geography, and 21 moreBiogeomorphology, Geographic Information Systems (GIS), Remote Sensing, Environmental science and policy, Modeling and Simulation, Remote sensing and GIS, Modeling, Remote Sensing (Earth Sciences), Population ecology, Environmental Remote Sensing, Ecological Modeling, Historical Biogeography, Habitat Mapping, Sandy Beaches, Nesting Shorebirds, Beach ecology, Shorebird Ecology, Open Source Software, Qgis, Postgis, and Coastal Processesedit
- In my research, I am documenting and researching California's beach plants, following the work of Michael Barbour in ... moreIn my research, I am documenting and researching California's beach plants, following the work of Michael Barbour in this field. My work ranges from field measurements and transects to remote sensing and covers the California coast from Redwoods National Park to Leo Carrillo State Park.
My remote sensing work focuses on finding a remote sensing system that will help assess the current state of beach plants at a given site. I am comparing ground sampling measurements with data collected from images taken from a hobby remote controlled hot air balloon. As an extension of my graduate work, I have begun working with kite aerial photography for coastal areas. Video of flights of both rigs is available at www.youtube.com/MicheleTobias
More information about my recent research, including aerial photography, can be found at my research website: https://sites.google.com/site/mtobiasresearch/
And follow me on Twitter: @MicheleTobiasedit
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Objectives:Early-life socioeconomic status (SES) and adversity are associated with late-life cognition and risk of dementia. We examined the association between early-life SES and adversity and late-life cross-sectional cognitive outcomes... more
Objectives:Early-life socioeconomic status (SES) and adversity are associated with late-life cognition and risk of dementia. We examined the association between early-life SES and adversity and late-life cross-sectional cognitive outcomes as well as global cognitive decline, hypothesizing that adulthood SES would mediate these associations.Methods:Our sample (N = 837) was a racially and ethnically diverse cohort of non-Hispanic/Latino White (48%), Black (27%), and Hispanic/Latino (19%) participants from Northern California. Participant addresses were geocoded to the level of the census tract, and US Census Tract 2010 variables (e.g., percent with high school diploma) were extracted and combined to create a neighborhood SES composite. We used multilevel latent variable models to estimate early-life (e.g., parental education, whether participant ever went hungry) and adult (participant’s education, main occupation) SES factors and their associations with cross-sectional and longitudinal cognitive outcomes of episodic memory, semantic memory, executive function, and spatial ability.Results:Child and adult factors were strongly related to domain-specific cognitive intercepts (0.20–0.48 SD per SD of SES factor); in contrast, SES factors were not related to global cognitive change (0.001–0.01 SD per year per SD of SES factor). Adulthood SES mediated a large percentage (68–75%) of the total early-life effect on cognition.Conclusions:Early-life sociocontextual factors are more strongly associated with cross-sectional late-life cognitive performance compared to cognitive change; this effect is largely mediated through associations with adulthood SES.
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<p>Original Publication: http://www.tandfonline.com/doi/abs/10.1080/02723646.2014.966224</p> <p> </p> <p>Kudos (easy to read) Description:... more
<p>Original Publication: http://www.tandfonline.com/doi/abs/10.1080/02723646.2014.966224</p> <p> </p> <p>Kudos (easy to read) Description: https://www.growkudos.com/articles/10.1080/02723646.2014.966224?hc_location=ufi</p
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<p>This figure descibes the relationship between the four main input tables for Marxan.</p
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<p>This is the citation list that accompanies the map A California Research Review for California's Beach Plants</p
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The approximate location of the first railroad to reach California from the east had its origins in the congressional debate over slavery prior to the Civil War. The precise location of track took years to define. By comparing two sets of... more
The approximate location of the first railroad to reach California from the east had its origins in the congressional debate over slavery prior to the Civil War. The precise location of track took years to define. By comparing two sets of historical maps in the California State Archives, this article examines how the route of the Central Pacific Railroad evolved from a plausible engineering concept to the busy track it is today. This occurred at the hands of Congress, a pharmacist, an engineer, and the engineer’s assistant, in response to national politics, local business concerns, balance sheets, and the limits of railway construction technology in the 1860s.
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Foredune plant species are a prime example of biogeomorphic agents, building foredunes by stopping the landward movement of sand and holding it in place. The association of these plant species with specific landforms and their... more
Foredune plant species are a prime example of biogeomorphic agents, building foredunes by stopping the landward movement of sand and holding it in place. The association of these plant species with specific landforms and their biogeomorphic roles in the process of foredune building for California was previously not well understood. Studies of foredune plants have focused on a narrow geographic range or addressed purely ecological conditions associated with foredune plants, omitting the biogeomorphic role of these species. This study derives foredune plant-landform associations across a wide latitude of the California coastline and synthesizes a conceptual model of dune biogeomorphic succession that encompasses prior, geographically restricted studies. Measurements of habitat conditions (distance and elevation from high water line and slope angle) were used in a cluster analysis to produce groups of species that were compared with groups identified in previous studies. From these groups, a conceptual model of California’s foredune biogeomorphology was constructed. Groups resulting from the cluster analysis (leading-edge pioneer builders, mid-strand pioneer stabilizers, sheltered secondary builders, sheltered secondary stabilizers, and sheltered tertiary stabilizers) correspond well with groups described in previous studies and define functional groups that can be applied across the state to understand the process of dune building.
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INTRODUCTION: To investigate current abortion access in the United States based on geographic location and to forecast access according to the landscape of abortion care in the year after the Dobbs v Jackson Women’s Health Organization... more
INTRODUCTION: To investigate current abortion access in the United States based on geographic location and to forecast access according to the landscape of abortion care in the year after the Dobbs v Jackson Women’s Health Organization decision. METHODS: Addresses of abortion-providing clinics were identified using web-based directories from Planned Parenthood, the National Abortion Foundation, Abortion Finder, and Power to Decide. Using geographic coordinates and the OpenStreetMap road network, Valhalla's Isochrone application programming interface was used to calculate the areas within a 30-, 60-, and 90-minute driving distance from these clinics. The population of reproductive-aged women (15–49 years) in the tracts inside or outside the accessible areas was determined using the U.S. Census American Community Survey for 2020. Review of legislative and judicial actions for 2023 determined at-risk states. Clinic locations and laws are accurate as of June 2, 2023. RESULTS: The ad...
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Objectives: Early-life socioeconomic status (SES) and adversity are associated with late-life cognition and risk of dementia. We examined the association between early-life SES and adversity and late-life cross-sectional cognitive... more
Objectives: Early-life socioeconomic status (SES) and adversity are associated with late-life cognition and risk of dementia. We examined the association between early-life SES and adversity and late-life cross-sectional cognitive outcomes as well as global cognitive decline, hypothesizing that adulthood SES would mediate these associations. Methods: Our sample (N = 837) was a racially and ethnically diverse cohort of non-Hispanic/Latino White (48%), Black (27%), and Hispanic/Latino (19%) participants from Northern California. Participant addresses were geocoded to the level of the census tract, and US Census Tract 2010 variables (e.g., percent with high school diploma) were extracted and combined to create a neighborhood SES composite. We used multilevel latent variable models to estimate early-life (e.g., parental education, whether participant ever went hungry) and adult (participant’s education, main occupation) SES factors and their associations with cross-sectional and longitu...
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Social determinants of health, including neighborhood factors, play a key role in the health of diverse older adults. However, few longitudinal studies have examined the role of neighborhood racial/ethnic segregation on cognitive decline... more
Social determinants of health, including neighborhood factors, play a key role in the health of diverse older adults. However, few longitudinal studies have examined the role of neighborhood racial/ethnic segregation on cognitive decline in diverse samples. We examined older non-Hispanic White (NHW), Black, and Latino participants evaluated at an Alzheimer's Disease Research Center. Neighborhood racial/ethnic segregation was measured using the Getis-Ord Gi* statistic, a spatial measure of clustering that was created for Latino and Black clustering separately. Cognitive outcomes included episodic memory, semantic memory, and executive function. We used mixed effects multivariable regression models to evaluate associations between segregation and cognitive function and decline. We had 452 individuals: 46% NHW, 26% Black, and 21% Latino in 309 census tracts with an average of 5.2 years of follow-up data (range 0.6-15.0). In analyses that adjusted for a variety of covariates (including neighborhood SES), individuals in neighborhoods with a higher clustering of Latino residents (higher Gi* statistic) had slower declines over time on semantic memory and those in neighborhoods with a higher clustering of Black residents had slower declines over time on episodic memory. In race/ethnicity-stratified adjusted analyses: for Black participants, the association between clustering and cognition was present for episodic memory and executive function, showing lower baseline scores in highly clustered Black and Latino neighborhoods, respectively. There was no association with cognitive change. Among Latino participants, highly clustered Latino neighborhoods were associated with lower baseline scores in semantic memory, but slower declines in episodic memory; Latinos living in neighborhoods with a greater clustering of Black residents also had slower declines in episodic memory. Among NHWs, residing in neighborhoods with a higher clustering of Latino residents was associated with slower declines over time on semantic memory. Segregated neighborhoods may be differentially associated with cognitive outcomes depending on individual race/ethnicity.
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This release will allow Zendo to create a DOI for this project. No updates to the code have been made.
This is a set of three files to be used in a workshop on spatial SQL in SpatiaLite
This map provides a visual reference to study site locations in scientific research articles on beach plants from 1900 to 2010, highlights spatial gaps in the literature, and describes temporal publication trends. This map is intended to... more
This map provides a visual reference to study site locations in scientific research articles on beach plants from 1900 to 2010, highlights spatial gaps in the literature, and describes temporal publication trends. This map is intended to be accompanied by a list of full citations for the mapped literature.
Traditional approaches to interpolating a surface from point samples often assume that if anisotropy is present in the data, it is along a straight line. However, this assumption breaks down for many data-sets, such as river bathymetry,... more
Traditional approaches to interpolating a surface from point samples often assume that if anisotropy is present in the data, it is along a straight line. However, this assumption breaks down for many data-sets, such as river bathymetry, elevations near coastlines, or levels of pollutants along roads. I will present a work-flow using open source tools to make use of the curvilinear anisotropy present in many data-sets by transforming the curved data-set into a straight line (QGIS and PostGIS), applying an interpolation to the transformed data (SAGA, GRASS, or other program with interpolation tools), and finally re-bending the interpolated surface back to the data's original shape (PostGIS).
Social determinants of health, including neighborhood factors, play a key role in the health of diverse older adults. Yet few longitudinal studies have examined the role of neighborhood racial/ethnic segregation on cognitive function and... more
Social determinants of health, including neighborhood factors, play a key role in the health of diverse older adults. Yet few longitudinal studies have examined the role of neighborhood racial/ethnic segregation on cognitive function and cognitive decline in both Latinos and Blacks, two populations at greater risk for Alzheimer’s disease and related dementias. We examined how one measure of residential segregation is associated with cognitive outcomes in a diverse cohort.
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Studying vegetation on California&#39;s beaches has been problematic with remote sensing. Commonly available imagery, such as satellite imagery or aerial photographs, may not be of sufficiently large scale to identify species of beach... more
Studying vegetation on California&#39;s beaches has been problematic with remote sensing. Commonly available imagery, such as satellite imagery or aerial photographs, may not be of sufficiently large scale to identify species of beach plants, which rarely form large dense stands. Large amounts of light reflected from the sand can obscure plants in aerial photographs. Fine scale imagery collected over the site, on site, could provide the solution to some common remote sensing problems associated with beach vegetation. A balloon-mounted camera was flown over UCSB&#39;s Coal Oil Point Reserve to collect aerial photographs with one pixel corresponding to three to five mm2 on the ground. The lower flying height and greater flexibility in timing of image acquisition with an unmanned aerial vehicle (UAV) proved to be a satisfactory solution. This study tested the feasibility of using a UAV to collect usable remote sensing data for the beach ecosystem, and identifies the spectral signatures of four common plant species and four types of substrate at one beach.
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California beach plants are capable of dealing with harsh conditions, but little is known about how this community responds to human-induced impacts. The objective of this paper is to determine if beaches experiencing higher degrees of... more
California beach plants are capable of dealing with harsh conditions, but little is known about how this community responds to human-induced impacts. The objective of this paper is to determine if beaches experiencing higher degrees of impacts from trampling have more cover of two common plant species thought to grow particularly well under difficult conditions, Ambrosia chamissonis (Less.) Greene and Cakile maritima Scop. Seventeen sites were sampled between 2007 and 2009 with one meter wide belt transects and the sites were divided into three groups; high (people walk anywhere on the beach), medium (foot traffic is restricted to trails), and low impact levels (little to no access). Cover of all species present were recorded. Cover of A. chamissonis is statistically higher on beaches with a high level of impact than low and medium levels. Cakile maritima cover is statistically higher on beaches with medium levels than those with low or high levels of impact. However, the total cover of all species is not significantly different between any level of impact.
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Foredune plant species are a prime example of biogeomorphic agents, building foredunes by stopping the landward movement of sand and holding it in place. The association of these plant species with specific landforms and their... more
Foredune plant species are a prime example of biogeomorphic agents, building foredunes by stopping the landward movement of sand and holding it in place. The association of these plant species with specific landforms and their biogeomorphic roles in the process of foredune building for California was previously not well understood. Studies of foredune plants have focused on a narrow geographic range or addressed purely ecological conditions associated with foredune plants, omitting the biogeomorphic role of these species. This study derives foredune plant-landform associations across a wide latitude of the California coastline and synthesizes a conceptual model of dune biogeomorphic succession that encompasses prior, geographically restricted studies. Measurements of habitat conditions (distance and elevation from high water line and slope angle) were used in a cluster analysis to produce groups of species that were compared with groups identified in previous studies. From these groups, a conceptual model of California’s foredune biogeomorphology was constructed. Groups resulting from the cluster analysis (leading-edge pioneer builders, mid-strand pioneer stabilizers, sheltered secondary builders, sheltered secondary stabilizers, and sheltered tertiary stabilizers) correspond well with groups described in previous studies and define functional groups that can be applied across the state to understand the process of dune building.
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The approximate location of the first railroad to reach California from the east had its origins in the congressional debate over slavery prior to the Civil War. The precise location of track took years to define. By comparing two sets of... more
The approximate location of the first railroad to reach California from the east had its origins in the congressional debate over slavery prior to the Civil War. The precise location of track took years to define. By comparing two sets of historical maps in the California State Archives, this article examines how the route of the Central Pacific Railroad evolved from a plausible engineering concept to the busy track it is today. This occurred at the hands of Congress, a pharmacist, an engineer, and the engineer’s assistant, in response to national politics, local business concerns, balance sheets, and the limits of railway construction technology in the 1860s.
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Many studies in air, soil, and water research involve observations and sampling of a specific location. Knowing where studies have been previously undertaken can be a valuable addition to future research, including understanding the... more
Many studies in air, soil, and water research involve observations and sampling of a specific location. Knowing where studies have been previously undertaken can be a valuable addition to future research, including understanding the geographical context of previously published literature and selecting future study sites. Here, we introduce Literature Mapper, a Python QGIS plugin that provides a method for creating a spatial bibliography manager as well as a specification for storing spatial data in a bibliography manager. Literature Mapper uses QGIS’ spatial capabilities to allow users to digitize and add location information to a Zotero library, a free and open-source bibliography manager on basemaps or other geographic data of the user’s choice. Literature Mapper enhances the citations in a user’s online Zotero database with geolocations by storing spatial coordinates as part of traditional citation entries. Literature Mapper receives data from and sends data to the user’s online ...
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Foredune plant species are a prime example of biogeomorphic agents, building foredunes by stopping the landward movement of sand and holding it in place. The association of these plant species with specific landforms and their... more
Foredune plant species are a prime example of biogeomorphic agents, building foredunes by stopping the landward movement of sand and holding it in place. The association of these plant species with specific landforms and their biogeomorphic roles in the process of foredune building for California was previously not well
understood. Studies of foredune plants have focused on a narrow geographic range or addressed purely ecological conditions associated with foredune plants, omitting
the biogeomorphic role of these species. This study derives foredune plant-landform associations across a wide latitude of the California coastline and synthesizes a conceptual
model of dune biogeomorphic succession that encompasses prior, geographically restricted studies. Measurements of habitat conditions (distance and elevation from high water line and slope angle) were used in a cluster analysis to produce
groups of species that were compared with groups identified in previous studies. From these groups, a conceptual model of California’s foredune biogeomorphology was constructed. Groups resulting from the cluster analysis (leading-edge pioneer builders, mid-strand pioneer stabilizers, sheltered secondary builders, sheltered secondary stabilizers, and sheltered tertiary stabilizers) correspond well with groups described in previous studies and define functional groups that can be applied across the state to understand the process of dune building.
understood. Studies of foredune plants have focused on a narrow geographic range or addressed purely ecological conditions associated with foredune plants, omitting
the biogeomorphic role of these species. This study derives foredune plant-landform associations across a wide latitude of the California coastline and synthesizes a conceptual
model of dune biogeomorphic succession that encompasses prior, geographically restricted studies. Measurements of habitat conditions (distance and elevation from high water line and slope angle) were used in a cluster analysis to produce
groups of species that were compared with groups identified in previous studies. From these groups, a conceptual model of California’s foredune biogeomorphology was constructed. Groups resulting from the cluster analysis (leading-edge pioneer builders, mid-strand pioneer stabilizers, sheltered secondary builders, sheltered secondary stabilizers, and sheltered tertiary stabilizers) correspond well with groups described in previous studies and define functional groups that can be applied across the state to understand the process of dune building.
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Plover is a program written in VB.net to model a subpopulation of Western Snowy Plovers (Charadrius alexandrinus nivosus). The model is based on data and observations in scientific literature. It was intended to assist managers in... more
Plover is a program written in VB.net to model a subpopulation of Western Snowy Plovers (Charadrius alexandrinus nivosus). The model is based on data and observations in scientific literature. It was intended to assist managers in understanding how management decisions could potentially affect a local population. The results of this model underscore the need to protect Western Snowy Plovers from human impacts.
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The goal of this study was to determine how digital photogrammetry can be used to describe and monitor shorebird habitat. Methods previously used for monitoring beach erosion were applied to shorebird habitat, concentrating on the... more
The goal of this study was to determine how digital photogrammetry can be used to describe and monitor shorebird habitat. Methods previously used for monitoring beach erosion were applied to shorebird habitat, concentrating on the requirements of Western Snowy Plovers. How the physical habitat of Western Snowy Plovers has changed over time was investigated at Sand Beach, which is part of Coal Oil Point Reserve in Santa Barbara, California, from 1928 to 2004, using width, area, and elevation data gathered from a series of aerial photographs. Single georeferenced photographs were used to measure width at regular intervals and area for each year a photo was available. Georeferenced aerial photographs can be used to obtain accurate measurements of beach area and width. Orthorectification is not necessary if photos can be georeferenced with minimal error. Sands Beach was found to be increasing in area. This was due mainly to the retreat of the vegetation line as the mouth of Devereux Slough shifted in 1992 rather than an accumulation of sand on the beach.
Research Interests: Physical Geography, Remote Sensing, Coastal Geomorphology, Remote Sensing (Earth Sciences), Environmental Remote Sensing, and 10 moreBiogeography, Remote sensing and GIS, Historical Biogeography, Sandy Beaches, Habitat Mapping, Beach ecology, Shorebird Ecology, Beaches and human interaction, Nesting Shorebirds, and Western Snowy Plover
The goal of this study was to determine how softcopy digital photogrammetry can be used to describe and monitor shorebird habitat. I focused on applying monitoring methods previously used for beach erosions studies of tourist beaches to... more
The goal of this study was to determine how softcopy digital photogrammetry can be used to describe and monitor shorebird habitat. I focused on applying monitoring methods previously used for beach erosions studies of tourist beaches to shorebird habitat concentrating on the habitat requirements of Western Snowy Plovers. I investigated how the physical habitat of Western Snowy Plovers has changed over time at Sand Beach, which is part of Coal Oil Point Reserve in Santa Barbara, California, from 1928 to the present day, using width, area, and elevation data gathered from a series of aerial photographs. For two-dimensional analysis, I used single georeferenced photographs to measure width at regular intervals and area for each year a photo was available. Next, for three-dimensional analysis, I employed digital elevation models (DEMs) built from stereo photographs to explore whether the available photos can be used to document changes in the elevation of Sands Beach.
The results were mixed. Georeferenced aerial photographs can be used to obtain quality measurements of beach area and width. Orthorectification is not necessary if photos can be georeferenced with minimal error. The amount of error present in the georeferenced images was indicated by the root mean squared error. A higher root mean squared error in the referencing process resulted in lower accuracy. Given the available photos and ground control points, I was unable to build digital elevation models with high enough quality to compare elevation from one year to the next. This was more likely due to a need for more ground control points than to the image scale or image errors.
The area of Sands Beach was found to be increasing in area. This was due mainly to the retreat of the vegetation line as the mouth of Devereux Slough shifted in 1992 rather than an accumulation of sand on the beach.
The results were mixed. Georeferenced aerial photographs can be used to obtain quality measurements of beach area and width. Orthorectification is not necessary if photos can be georeferenced with minimal error. The amount of error present in the georeferenced images was indicated by the root mean squared error. A higher root mean squared error in the referencing process resulted in lower accuracy. Given the available photos and ground control points, I was unable to build digital elevation models with high enough quality to compare elevation from one year to the next. This was more likely due to a need for more ground control points than to the image scale or image errors.
The area of Sands Beach was found to be increasing in area. This was due mainly to the retreat of the vegetation line as the mouth of Devereux Slough shifted in 1992 rather than an accumulation of sand on the beach.