Todd Esque
Dr. Todd Esque's research interests are in disturbance ecology with emphasis in areas of community ecology, herpetology, invasive species and fire, habitat restoration, and conservation biology.
Dr. Esque's work focuses on understanding how organisms, habitats, and ecosystem processes respond to environmental change, how organisms interact to effect change, and how human-induced changes compare to the natural range of variation in arid systems. Recent work focuses on the synthesis of these experiments into regional analyses of habitat suitability and connectivity in response to global change and other anthropogenic disturbances for use by natural resource managers.
Representative studies include: projects to determine how desert tortoises, Mojave ground squirrels, golden eagles, long-lived plants, and biodiversity will respond to climate change and energy development in a rapidly changing landscape; vegetation change from fires across a 30-year chronosequence in Sonoran desert tortoise habitat; identifying habitat and health relationships for the desert tortoise, and developing a vegetation restoration program for the Mojave Desert.
Dr. Esque's projects are collaborative and interdisciplinary in nature and he is active in academic research as well as applied problems for public entities in the Department of Interior (Bureau of Land Management, National Park Service, U.S. Fish and Wildlife Service), Department of Defense, State and local governments, and private entities.
RESEARCH INTERESTS
- Arid Systems
- Conservation Biology
- Disturbance and Restoration Ecology
- Demographic and Habitat Modeling
- Community Ecology
- Invasive Species and Wildfire
- Energy Development
EDUCATION
- 2004 Ph.D. Ecology Evolution, and Conservation Biology, University of Nevada, Reno
- 1994 M.S. Zoology, Colorado State University
- 1982 B.A. Biology, Prescott College, Arizona
PROFESSIONAL AND HONORARY SOCIETIES AND SCIENCE ADVISORY COMMITTEES
- Desert Renewable Energy Conservation Plan – Science Advisory Committee 2012
- BLM – Rapid Ecoregional Assessments – lead USGS science reviewer for the Mojave and Sonoran Ecoregions 2013
PROFESSIONAL EXPERIENCE
- Research Ecologist, USGS, Western Ecological Research Center, 1997-Present
- Station Leader, USGS, St. George Field Station, 1994-1997
- Research Ecologist, USGS, Mid-continent Ecological Science Center, 1996- 1997
- Research Ecologist, National Biological Service (Survey), Mid-continent Ecological Science Center, 1993 - 1996
- Ecologist, Bureau of Land Management, Dixie Resource Area, Utah, 1993 - 1993
- Research Technician, Fish and Wildlife Service, Region 8, Research, Ft. Collins, CO 1986-1993
Science and Products
Gopherus agassizii (Agassiz’s desert tortoise). scute dysecdysis/scute sloughing
Supplementing seed banks to rehabilitate disturbed Mojave Desert shrublands: Where do all the seeds go?
Does translocation influence physiological stress in the desert tortoise?
Long-term change in perennial vegetation along the Colorado river in Grand Canyon national park (1889-2010)
Repeat photography and low-elevation fire responses in the southwestern United States
Demographic studies of Joshua trees in Mojave Desert National Parks: demography with emphasis on germination and recruitment
Making molehills out of mountains: Landscape genetics of the Mojave desert tortoise
Effects of subsidized predators, resource variability, and human population density on desert tortoise populations in the Mojave Desert, USA
Short-term effects of experimental fires on a Mojave Desert seed bank
Desert wildfire and severe drought diminish survivorship of the long-lived Joshua Tree (Yucca brevifolia; Agavaceae)
Seed banks in a degraded desert shrubland: Influence of soil surface condition and harvester ant activity on seed abundance
Divergence in an obligate mutualism is not explained by divergent climatic factors
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Gopherus agassizii (Agassiz’s desert tortoise). scute dysecdysis/scute sloughing
Desert tortoises with scute injuries due to fire or disease related processes can result in loss of the scute. These animals appear to function normally, and can replace the scute material with a keratinized layer that covers the bone. This paper describes a tortoise with severe scute loss from a wildfire in 2005, and an animal that lost its scute for unknown reasons. Both animals appeared to be hAuthorsKenneth E. Nussear, K. Kristina Drake, Phil A. Medica, Todd C. EsqueSupplementing seed banks to rehabilitate disturbed Mojave Desert shrublands: Where do all the seeds go?
Revegetation of degraded arid lands often involves supplementing impoverished seed banks and improving the seedbed, yet these approaches frequently fail. To understand these failures, we tracked the fates of seeds for six shrub species that were broadcast across two contrasting surface disturbances common to the Mojave Desert—sites compacted by concentrated vehicle use and trenched sites where topAuthorsLesley A. DeFalco, Todd C. Esque, Melissa B. Nicklas, Jeffrey M. KaneDoes translocation influence physiological stress in the desert tortoise?
Wildlife translocation is increasingly used to mitigate disturbances to animals or habitat due to human activities, yet little is known about the extent to which translocating animals causes stress. To understand the relationship between physiological stress and translocation, we conducted a multiyear study (2007–2009) using a population of desert tortoises (Gopherus agassizii) near Fort Irwin, CaAuthorsK.K. Drake, K.E. Nussear, T. C. Esque, A.M. Barber, K.M. Vittum, P.A. Medica, C.R. Tracy, K.W. HunterLong-term change in perennial vegetation along the Colorado river in Grand Canyon national park (1889-2010)
Long-term monitoring data are difficult to obtain for high-value resource areas, particularly in remote parts of national parks. One long-used method for evaluating change uses ground-based repeat photography to match historical images of landscapes. River expeditions that documented a proposed railroad route through Grand Canyon with large-format photographs occurred in 1889 and 1890. A total ofAuthorsR. H. Webb, Jayne Belnap, M.L. Scott, Todd C. EsqueRepeat photography and low-elevation fire responses in the southwestern United States
No abstract available.AuthorsR. M. Turner, R. H. Webb, T. C. Esque, G.F. RogersDemographic studies of Joshua trees in Mojave Desert National Parks: demography with emphasis on germination and recruitment
The study of population change with regard to reproduction, seed dispersal, and germination, establishment, growth, and survival/mortality is known as demography. Demographic studies provide managers with information to assess future trends on the density, distribution, health, and population changes of importance or value, including Joshua trees (Yucca brevifolia). Demographic research provides tAuthorsT. C. Esque, B. Reynolds, L.A. DeFalco, B.A. WaitmanMaking molehills out of mountains: Landscape genetics of the Mojave desert tortoise
Heterogeneity in habitat often influences how organisms traverse the landscape matrix that connects populations. Understanding landscape connectivity is important to determine the ecological processes that influence those movements, which lead to evolutionary change due to gene flow. Here, we used landscape genetics and statistical models to evaluate hypotheses that could explain isolation among lAuthorsBridgette E. Hagerty, Kenneth E. Nussear, Todd C. Esque, C. Richard TracyEffects of subsidized predators, resource variability, and human population density on desert tortoise populations in the Mojave Desert, USA
Understanding predator–prey relationships can be pivotal in the conservation of species. For 2 decades, desert tortoise Gopherus agassizii populations have declined, yet quantitative evidence regarding the causes of declines is scarce. In 2005, Ft. Irwin National Training Center, California, USA, implemented a translocation project including 2 yr of baseline monitoring of desert tortoises. UnusualAuthorsTodd C. Esque, Kenneth E. Nussear, K. Kristina Drake, Andrew D. Walde, Kristin H. Berry, Roy C. Averill-Murray, A. Peter Woodman, William I. Boarman, Phil A. Medica, Jeremy S. Mack, Jill S. HeatonShort-term effects of experimental fires on a Mojave Desert seed bank
A Mojave Desert shrub community was experimentally burned to understand changes in seed bank of desert annual plant species in response to wildfire. Seed mortality ranged from 55 to 80%, and fire caused significant losses of native and alien annual seeds. Schismus arabicus, Schismus barbatus, Bromus madritensis, Bromus tectorum, Erodium cicutarium and Plantago spp. made up >95% of the seed bank. BAuthorsTodd C. Esque, James A. Young, C. Richard TracyDesert wildfire and severe drought diminish survivorship of the long-lived Joshua Tree (Yucca brevifolia; Agavaceae)
Extreme climate events are transforming plant communities in the desert Southwest of the United States. Abundant precipitation in 1998 associated with El Ni??o Southern Oscillation (ENSO) stimulated exceptional alien annual plant production in the Mojave Desert that fueled wildfires in 1999. Exacerbated by protracted drought, 80% of the burned Yucca brevifolia, a long-lived arborescent monocot, anAuthorsL.A. DeFalco, T. C. Esque, S. J. Scoles-Sciulla, J. RodgersSeed banks in a degraded desert shrubland: Influence of soil surface condition and harvester ant activity on seed abundance
We compared seed banks between two contrasting anthropogenic surface disturbances (compacted, trenched) and adjacent undisturbed controls to determine whether site condition influences viable seed densities of perennial and annual Mojave Desert species. Viable seeds of perennials were rare in undisturbed areas (3-4 seeds/m2) and declined to <1 seed/m2 within disturbed sites. Annual seed densitiesAuthorsL.A. DeFalco, T. C. Esque, J.M. Kane, M.B. NicklasDivergence in an obligate mutualism is not explained by divergent climatic factors
Adaptation to divergent environments creates and maintains biological diversity, but we know little about the importance of different agents of ecological divergence. Coevolution in obligate mutualisms has been hypothesized to drive divergence, but this contention has rarely been tested against alternative ecological explanations. Here, we use a well-established example of coevolution in an obligaAuthorsW. Godsoe, Espen Strand, C.I. Smith, J.B. Yoder, T. C. Esque, O. Pellmyr - Web Tools
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