Joseph Sexton

Research Assistant Professor
  Office:   2138 LeFrak Hall
  University of Maryland
  College Park, MD 20742      
  Telephone:   301-405-8165 
  FAX:   301-314-9299 


Ph.D. Ecology, Duke University, 2009
M.S. Forest Ecology, Utah State University, 2003
B.S. Wildlife Ecology & Conservation (Zoology minor), University of Florida, 1999 

Research Interests

  • Ecosystem dynamics
  • Forest structure, growth, and phenology
  • Multi-temporal remote sensing
  • Species distribution modeling
Over the past century, Earth’s human population has risen from less than 2 billion to nearly 7 billion people. Much of this surge is attributed to technological advances that have shifted dominance in the human-nature relationship increasingly toward human control. Along with important social adaptations (e.g., demographic changes, migration to cities, etc.) the current “Anthropocene Era” has brought large changes in landform, hydrologic and biogeochemical cycles, climate, and biodiversity, as well as spatial patterns of land cover and human land use. Given the adversity of many of the impacts, these past and projected future changes have led to concern over the adaptability of societies and the long-term sustainability of human welfare.

Natural ecosystems are complex and potentially chaotic systems, even in the absence of anthropogenic influence. But with escalating human impacts, understanding the additional interactions between physical, biological, and social systems is increasingly crucial. Understanding the parts and linkages in coupled human-natural ecosystems is vital not only for conserving ecosystem function, but also for adapting socio-economic systems to their changing natural environment.

My research focuses on ecosystem dynamics and the remote sensing methods required to monitor landscape changes over time. I develop statistical and ecological analyses for the Global Forest Cover Change Project, a joint project of the Global Land Cover Facility, NASA's Goddard Space Flight Center, and South Dakota State University. This project is mining more than thirty years of Landsat images to map changes in Earth's forest cover from 1975 to 2005. Beyond my responsibilities to this major effort, I contribute ecological, statistical, and remote sensing expertise to collaborative studies of urban heat islands, threatened and endangered species habitat, tropical deforestation, climate effects on boreal biomes, and urban growth.

Before joining the University of Maryland Department of Geography in July, 2010, Dr. Sexton was a research associate at NASA's Goddard Space Flight Center Biospheric Sciences Branch, employed through the University of Marlyand Baltimore County's GEST program (2009-2010).

Representative Publications

Menke, S.B., B. Guenard, J.O. Sexton, R.R. Dunn, J. Silverman. in press. Urban areas may serve as habitat and corridors for dry-adapted, heat-tolerant species: an example from ants. Urban Ecosystems [pdf]

Westervelt, J., T. BenDor, J.O. Sexton. in press. A technique for rapidly forecasting regional urban growth. Environment & Planning B

Conde, D., F. Colchero, H. Zarza, N. Christensen, J.O. Sexton, C. Manterola, C. Chavez, A. Rivera, D. Azuara, G. Ceballos. 2010. Sex matters: modeling male and female jaguar habitat for conservation. Biological Conservation 143: 1980-1988 [pdf]

Bartel, R.A. and J.O. Sexton.. 2009. Monitoring habitat dynamics for rare and endangered species using satellite images and niche-based models. Ecography 32: 888-896 [pdf]

Whitehurst, A.S., J.O. Sexton, L. Dollar. 2009. Land cover change in western Madagascar's dry deciduous forests: a comparison of changes in and around Kirindy Mite National Park. Oryx 43:275-283 [pdf]

Sexton, J.O., T.V. Bax, P. Siqueria, J.J. Swenson, S. Hensley. 2009. A comparison of lidar, radar, and field measurements of canopy height in pine and hardwood forests of southeastern North America. Forest Ecology and Management 257: 1136-1147 [pdf]

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: 301-311 [pdf]