Joseph O. Sexton


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1. Research

1.1. Purpose

I study ecological landscapes to inform ecosystem management. An ecosystem is a community of organisms interacting with its environment, and landscapes are spatially interactive ecosystems. If managed well, landscapes provide countless benefits to Earth's human population and can adapt to fulfill our changing demands on them. If managed poorly however, landscapes might not only fail to provide the expected benefits (e.g., timber, water, wildlife, climate moderation, and aesthetic beauty) but can lose their adaptability and even propagate such costs as disease, plant and animal pests, floods, and wildfire. Landscape processes determine the spatiotemporal distribution of every ecosystem phenomenon, and so I contribute to ecosystem management by improving scientific understanding of landscape processes, developing ecological modeling and analysis tools, and communicating with those managing the landscapes on which we all depend.

Information is expensive however, and although the geographic information system (GIS) greatly reduces handling costs, spatial information is no exception. Consequently, many of the most articulate theories of ecology cannot be applied at management-relevant scales due to the immense computation necessary to do so. Consider the forecasting utility of a model that runs more slowly than reality, or the monitoring utility of a measurement that can only be collected over a tiny, biased fraction of a given landscape. Conversely, managers responsible for extensive landscapes can rarely afford to plan or act at the resolution of our most elaborate theories, except possibly by using them as rough guiding principles. To bridge this gap between ecology and land management and to help managers make better use of ecology, new measurements, models, and ultimately theories must be developed that are applicable at spatiotemporal scales relevant to modern land management.

1.2. Methods

I apply basic ecological principles to model actual landscapes as virtual landscapes in GIS. I populate the landscapes with ecological parameters estimated from remotely sensed and field-measured data and analyze relationships through multivariate and spatial statistical methods. I then model patterns induced from these landscapes to forecast predictions based on various scenarios of management action. Each prediction is a spatially explicit ecological hypothesis to be tested by management action. With monitoring and adaptation of the model, recursion of this process allows landscapes to adapt favorably to future scenarios.

1.3. Topics

Specifically, I study temperate forest landscapes. These landscapes are continually changing in feedback with climate, urbanization, and to the different management objectives of a constantly changing human appetite. Such complex dynamics provide a constant challenge, one that requires constant awareness of new data sources, statistical techniques, and most importantly, current land management concerns.

Some of my current research interests are listed below:

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1.4. Projects

Suburban forest dynamics: phenology, succession, and urbanization in the North Carolina Piedmont. [page]

Habitone analysis of quaking aspen in the Utah Book Cliffs. [page]

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2. Curriculum vitae [PDF]

2.1. Education

B.S. cum laude. University of Florida, Department of Wildlife Ecology and Conservation. 1999.

M.S. magna cum laude. Utah State University, Department of Forest Resources. 2003. [thesis]

Ph.D. (candidate) Duke University, Nicholas School of the Environment and Earth Sciences. expected 2008.

2.2. Employment

Research Fellow, NASA Earth System Science Graduate Fellowship Program. Dean Urban, advisor. 2005 - [2008];

Teaching Assistant. Landscape Ecology. Dean Urban, instructor. 2004, 2005;

Research Assistant. Landscape Ecology Lab, Duke University. Dean Urban, principal investigator. 2003 - 2005;

Research Assistant. RS/GIS Lab, Utah State University College of Natural Resources. R. Douglas Ramsey, principal investigator. 2000-2003;

Vice-presidential Research Fellow. Utah State University. Mike Jenkins, adivsor. 1999-2000;

Research Technician. South Carolina Cooperative Fish and Wildlife Research Unit. Clemson University. Craig Allen, principal investigator. 1999;

Research Assistant. University of Florida Department of Wildlife Ecology and Conservation. Lyn Branch, principal investigator. 1996 - 1999;

Forestry Research Intern. Tall Timbers Research Station. W. Keith Moser, principal investigator. 1998.

2.3. Honors

Sigma Xi Scientific Research Society associate member, 2006 – present.

Duke University Aleane Webb Dissertation Research Award, 2006.

Duke University Nicholas School of the Environment and Earth Sciences Professional Development Travel Award, 2006.

Duke University Graduate School Conference Travel Fellowship, 2006.

NASA Earth System Science Fellowship, 2005 - [2008].

United States Regional Chapter of the International Association for Landscape Ecology (US-IALE) NASA/MSU Professional Enhancement Award, 2005.

2nd Place, Student Poster Competition, Utah Geographic Information Council 2002 Annual Conference, Ruby’s Inn, Bryce Canyon National Park, 2002.

Xi Sigma Pi honorary forestry fraternity membership, 2000 - present.

Utah State University Vice-Presidential Fellowship for Graduate Research, 1999.

University of Florida Department of Wildlife Ecology and Conservation Jennings’ Scholarship, 1997.

Alpha Zeta honorary agricultural fraternity membership, 1995 - present.

University of Florida Out of State Tuition Waiver (scholarship awarded to the top 0.5% of incoming freshmen to the University), 1994 - 1999.

2.4. Selected presentations

Sexton, J.O., and D.L. Urban. 2008. Coupled natural and anthropogenic landcover dynamics on the North Carolina Piedmont. Annual Meeting of the Association of American Geographers, Boston , MA . April 15, 2008.

Sexton, J.O. and D.L. Urban. 2006. Change-vector analysis of forest succession: gradient effects on Piedmont forest dynamics. 21st Annual Symposium of the United States Regional Chapter of the International Association for Landscape Ecology. San Diego, CA, March 28 – April 1, 2006. [abstract]

Sexton, J.O., 2005. Habitone analysis of quaking aspen in the Book Cliffs (Utah, USA): effects of site water demand and conifer cover. 20th Annual Symposium of the United States Regional Chapter of the International Association for Landscape Ecology. Syracuse, NY, March 12-16, 2005. [abstract] Also presented as an invited lecture at Restoring the West Conference 2006 - Aspen Restoration. September 12-13, Utah State University, Logan, UT.

Sexton, J.O. and D.L. Urban, 2005. NPP-edge effects in suburban landscapes: measuring “edge” (poster). 20th Annual Symposium of the United States Regional Chapter of the International Association for Landscape Ecology. Syracuse, NY, March 12-16, 2005.

Sexton, J.O. 2003. The distribution of quaking aspen in geographic and potential evapotranspiration spaces relevant to the Book Cliffs (Utah), 2000-2002. Master’s thesis seminar. College of Natural Resources, Utah State University. July 2, 2003.

Sexton, J.O., R.D. Ramsey, J. Lowry, T.L. Sharik. 2002. A multiple-scale GIS framework for monitoring quaking aspen in the Intermountain West. Pecora 15/Land Satellite Information IV/ International Society for Photogrammetry and Remote Sensing (ISPRS) Commission I Symposium, Integrating remote sensing at the global, regional, and local scale. Denver, CO (USA), November 10-15, 2002. [abstract]

Sexton, J.O. 2002. Heuristics for interpreting empirically modeled raster data: fuzzy vs. probabilistic uncertainty and potential vs. actual landcover (poster). Utah Geographic Information Council 2002 Conference. September 18-20, 2002. Bryce Canyon National Park, Utah.

Sexton, J.O. 2002. Quaking aspen biogeography: issues of fuzzy vs. probabilistic classification and multispectral vs. environmental raster data (poster). The Ecological Society of America/ Society for Ecological Restoration 2002 Joint Annual Conference. August 7, 2002. Tucson, AZ.

Sexton, J.O.; A.F. Wells. 2002. Toward a synthesis of landscape and community ecologies: the generalization of scale. Utah State University Department of Forest Resources seminar, April 24, 2002.

Sexton, J.O.; M. Jenkins; T.L. Sharik; W. Wagner. 2000. A remotely sensed aspen deterioration classification for the study and management of quaking aspen in the Intermountain West (poster). Sustaining Aspen in Western Landscapes Symposium, Grand Junction, CO, June 13-15, 2000.

Sexton, J.O. 2000. A remotely-sensed cover classification to ‘scale up’ aspen monitoring and management. Utah State University Department of Forest Resources seminar, April 19, 2000. Logan, UT.


2.5. Selected publications

Bax, T.V., J.O. Sexton, P. Siqueria, J.J. Swenson. in review. A comparison of lidar, radar, and field methods for measuring canopy height in pine and hardwood forests of southeastern North America. Forest Ecology and Management.

Bartel, R.A and J.O. Sexton. in review . Monitoring habitat dynamics for rare and endangered species using satellite images. Ecological Applications.

Whitehurst, A.W., J.O. Sexton, L. Dollar. in press . Landcover change in western Madagascar 's dry deciduous forests: a comparison of changes in and around Kirindy Mite National Park . Oryx

Sexton, J.O.; R.D. Ramsey; D.L. Bartos. 2006. Habitone analysis of quaking aspen in the Utah Book Cliffs: effects of site water demand and conifer cover. Ecological Modelling 198 (3-4): 301-311 [PDF].

InSAR Working Group Reports Committee (34 authors). 2006. Interferometric Synthetic Aperture Radar (InSAR) Workshop Summary Report. InSAR Workshop, sponsored by NASA, NSF, and USGS. October 20-22, 2004. Oxnard, California. 64 pp. [site]

Sexton, J. O. 2003. Models for the distribution of quaking aspen in geographic and potential evapotranspiration spaces relevant to the Book Cliffs (Utah), 2000-2002. Master’s thesis, Dept. of Forest Resources, College of Natural Resources, Utah State University. Logan, UT. [thesis]


Sexton, J.; M. Jenkins; T. L. Sharik; W. Wagner. 2000. A remotely sensed aspen deterioration classification for the study and management of quaking aspen in the Intermountain West. abstract in Shepperd, W. D.; Binkley, D.; Bartos, D. L.; Stohlgren, T. J.; Eskew, L.. G., compilers. 2001. Sustaining Aspen in Western Landscapes, Symposium Proceedings; 13-15 June 2000; Grand Junction, CO. Proceedings RMRS-P-18. Fort Collins, CO: USDA Forest Service, Rocky Mountain Research Station. 460 pp.


2.6. Funding

Sexton, J.O. 2005. Carbon dynamics in heterogeneous landscapes: fusing remote sensing with spatial ecological models. NASA Earth System Science Fellowship. $72,000.

Ramsey, R.D.; T.L. Sharik; W. Wagner; J.O. Sexton. 2000. Determining the location, extent, condition, and trend of aspen communities in the Bookcliff Mountains. Vernal Field Office of the Bureau of Land Management Task Order. $35,300.


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