James M. Dyer

James Dyer
Professor of Geography

Ph.D. 1992, University of Georgia

My research focuses on North American forests, especially in the eastern United States. As a biogeographer, I am interested in the patterns that emerge from the interactions of the physical environment, biotic processes, and disturbance. Incorporating field work, spatial modeling, and geographic information science techniques, I am especially concerned with the role of humans in altering “natural” templates, and the implications for such change on biotic communities.

Below I describe in more detail my recent research projects, and information on courses I teach. Feel free to contact me if you have any questions, or if you have an interest in our graduate programs at Ohio University.

Contact
Information

e-mail:
phone:
fax:

mailing
address:

dyer@ohio.edu
740.593.1138
740.593.1139

Department of Geography
122 Clippinger Labs
Ohio University
Athens OH 45701

Jump to:

Downloads

Recent Research Projects

Research Presentation [streaming video]

Publications

Graduate Student Theses

Courses I Teach

Useful Links

Downloads

Water Balance Toolbox for ArcGIS and User Manual

from Dyer, J.M. 2009. Assessing topographic patterns in moisture use and stress using a water balance approach, Landscape Ecology 24: 391-403.

Revised Map of Braun's Forest Regions (image and ArcGIS shapefile)

from Dyer, J.M. 2006. Revisiting the Deciduous Forests of Eastern North America. BioScience 56: 341-352.

Maps of the Ridges Land Lab

Orthophotographs, historic air photos, land cover maps, trails & contour maps for Ohio University's Land Lab

Recent
Research
Projects

My recent research interests have focused on predicting vegetation-site relationships, using a water balance approach. Such an understanding is critical for assessing the effects of future climate change, or to evaluate changes related to historic land use patterns. Since plants respond to moisture supply and demand across all geographic scales, the water balance can serve as an effective predictor of continental range limits, or species occurrence within individual forest plots.

I also have been actively exploring changes in forest composition and structure in southeastern Ohio since settlement. I have used witness tree records to construct “baseline” vegetation patterns, then drew upon archival land use records, historic air photos, and field sampling to examining the role of historic land use in shaping the present-day flora of central Appalachian forests. Although southeastern Ohio is heavily forested today, land use practices have left distinctive “signatures” on these communities.

Currently I am involved in a study to monitor changes to Ohio’s hemlock forests, before the arrival of the invasive Hemlock Woolly Adelgid (HWA). HWA has resulted in high mortality in hemlock stands that it has infested in the eastern U.S., and its inevitable arrival into Ohio is likely to have devastating ecological and economic effects. In Ohio, hemlock forests occur in the eastern half of the state, and are often associated with steep slopes and ravines. Hemlock is a long-lived, shade-tolerant tree, and is often a dominant species in terms of its abundance and influence; this “foundation species” creates a unique microenvironment and provides habitat for animal species not typically associated with surrounding hardwood forests. With the spread of HWA westward across the Appalachian Mountains, Ohio is in an unfortunate but vital position to investigate ecosystem characteristics of hemlock forests, so that the full impact of the loss of this foundation species can be better understood. For this reason, my students and I have been collecting data on hemlock forests in southeastern Ohio since 2007. After establishing permanent plots, we have collected compositional data on the trees and herbs, tree-ring cores, and photographs. Since hemlock stands have distinctive light, temperature, and soil-nutrient conditions, we are also collecting soil samples and have installed microclimate data loggers. Ecologically, it is crucial that we establish baseline conditions of these unique forests before they are irrevocably altered by the introduction of HWA. Despite the sobering thought of the altered environmental conditions that will result with the loss of this keystone species, this study has provided an excellent opportunity to engage Ohio University students in applied environmental projects.


Hemlock Forest Lake Katharine State Nature Preserve	Hemlocks maintain their dense canopy of foliage year-round. Hemispheric photos enable us to track changing light conditions following the loss of hemlocks.	Photographing a permanent plot in Ash Cave State Park [credit: Nate Daniel]

Research Presentation

Click here to view a video of a presentation I made as part of the "New Professor Lecture Series," entitled Looking to the Past to Understand the Present: Two Hundred Years of Change in Eastern U.S. Forests. The talk, which took place March 9th, 2011, presents work I'd done over the previous decade. [Total video length: 48:45; Introduction by Dean Ben Ogles 0:00-2:50, Questions & Answers 40:30-48:45]

Publications

Click here to view abstracts

McEwan, R.W., J.M. Dyer, and N. Pederson. 2011. Multiple interacting ecosystem drivers: toward an encompassing hypothesis of oak forest dynamics across eastern North America. Ecography 34: 244-256.

Dyer, J.M. 2010. Land use legacies in a central Appalachian forest: Differential response of trees and herbs to historic agricultural practices. Applied Vegetation Science 13: 195-206.

Dyer, J.M. 2009. Assessing topographic patterns in moisture use and stress using a water balance approach. Landscape Ecology 24: 391-403. ArcGIS toolbox & user manual available as Download

Dyer, J.M., and C.M. Cowell, 2008. Invasive Species and the Resiliency of a Riparian Environment. Pages 87-103 in R.K. Kohli and S. Jose (eds.) Invasive Plants and Forest Ecosystems. CRC Press, Boca Raton, FL.

Dyer, J.M. 2006. Revisiting the Deciduous Forests of Eastern North America. BioScience 56: 341-352. Shapefile & image available as Download

Dyer, J.M. 2004. A water budget approach to predicting tree species growth and abundance, utilizing paleoclimatology sources. Climate Research 28: 1-10.

Dyer, J.M. 2002. A comparison of moisture scalars and water budget methods to assess vegetation-site relationships. Physical Geography, 23: 245-258.

Cowell, C.M., and J.M. Dyer. 2002. Vegetation development in a modified riparian environment: Human imprints on an Allegheny River Wilderness. Annals of the Association of American Geographers 92: 189-202.

Dyer, J.M. 2001. Using witness trees to assess forest change in southeastern Ohio. Canadian Journal of Forest Research, 31: 1708-1718.

Dyer, J.M., and K.E. Moffett. 1999. Meadow invasion from high-elevation spruce-fir forest in south-central New Mexico. The Southwestern Naturalist 44: 445-457.

Dyer, J.M., and P.R. Baird. 1997. Remnant forest stands at a prairie ecotone site: presettlement history and comparison with other maple-basswood stands. Physical Geography 18: 146-159.

Dyer, J.M., and P.R. Baird. 1997. Wind disturbance in remnant forest stands along the prairie-forest ecotone, Minnesota, U.S.A. Plant Ecology 129: 121-137.

Click here to see simulation of species migration in response to climate change

Pitelka, L.F., and The Plant Migration Workshop Group. 1997. Plant migration and climate change. American Scientist 85: 464-473.

Dyer, J.M. 1996. Considerations of scale and ecological processes in a forest migration model: a reply to Roth. Professional Geographer 48: 86-88.

Dyer, J.M. 1995. Assessment of climatic warming using a model of forest species migration. Ecological Modelling 79: 199-219.

Dyer, J.M. 1994. Implications of habitat fragmentation on climate change-induced forest migration. Professional Geographer 46: 449-459.

Dyer, J.M. 1994. Land use pattern, forest migration, and global warming. Landscape and Urban Planning 29: 77-83.

Dyer, J.M., and G.A. Brook. 1991. Spatial and temporal variations in temperate forest soil carbon dioxide during the non-growing season. Earth Surface Processes and Landforms 16: 411-426.

Graduate Student Theses I've Advised

Click here to view abstracts

American Chestnut Restoration in Eastern Hemlock-Dominated Forests of Southeast Ohio, Nathan Daniel, Environmental Studies MS 2012. (co-advisor: Brian McCarthy) [Link to PDF]

Spatial Distribution of Freshwater Mussels (Unionidae) in Ohio Brush Creek Watershed, Southern Ohio, Jason K. Brown, Geography MA 2010. [Link to PDF]

Microclimatic and Topographic Controls of Fire Radiative Energy in Southeastern Ohio, Loredana G. Suciu, Geography MA 2009. [Link to PDF]

Ecological Considerations for Risk Management of the Hemlock Woolly Adelgid in the Hocking Hills, Ohio USA, Nicole Stump, MSc 2008 (Albert-Ludwigs University).

Using Landscape Variables to Assess Stream Health in Ohio’s Western Allegheny Plateau, Lisa King, Geography MA 2008. [Link to PDF]

Predicting Infestations of Hemlock Woolly Adelgid (Adelges tsugae) in Great Smoky Mountains National Park Tennessee/North Carolina, USA, Scott Snider, Geography MA 2004.

Exotic Plant Colonization of the Forest Adjacent to Transmission Line Corridors in Athens County, Ohio, Kaabe Shaw, Environmental Studies MS 2002.

Linking Spatial Data with Population Viability Analysis: Reserve Network Design in the Northeastern Ecuadorian Amazon, Galo Zapato-Rios, Environmental Studies MS 2001.

Land Use Land Cover Change From 1915 to 1999 in The Gwynns Falls Watershed, Baltimore County, Maryland: Creation of a Suburban Social Ecology, Michael Wehling, Geography MA 2001. Click here to view a summary with figures.

The Biogeography of Gapper's Red-backed Vole (Clethrionomys gapperi): A Comparison of Genetic and Morphological Variation in Eastern North America, Emily Whitfield, Environmental Studies MS 1998.

Landscape Suitability: A Case Study of Wolf Habitat in North Dakota, Evan Moffett, Geography MA 1997.

Catastrophic Windthrow: A Case Study of the Allegheny River Wilderness Islands, Lisa DeChano, Geography MA 1997.

A Spatial Analysis of an Urban Fishery: A Case Study of Winnipeg, Manitoba, Ian Kitch, Geography MS 1994.



Courses I Teach	Click on course title for syllabus from most-recent offering (Click here if you need to download the Acrobat Reader.) Other course material available on Blackboard

	GEOG 101:	Physical Geography
	GEOG 316/516 (BIOS 316/516):	Biogeography
	GEOG 417/517:	Landscape Ecology
	GEOG 476/576:	Field Methods
	GEOG 570:	GIS Applications
	GEOG 681A:	Seminar in Biogeography

	General Information:	Common Term Paper Writing Errors
		Oral Presentation Guidelines
		Some Suggestions on Studying for Exams

		Careers in Geography: An introduction to what Geography is about

Last Updated 2 December 2011