||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 program at Ohio University.
Department of Geography
122 Clippinger Labs
Athens OH 45701
[Water Balance Toolbox, Shapefiles of Forest Regions and Ohio Hemlock, Maps of Ridges Land Lab]
Videos: Introduction to Tree Coring & Preparing Tree Cores for Analysis
Recent Research Projects
Research Presentation [streaming video]
Graduate Student Theses
Courses I Teach
||Water Balance Toolbox for
ArcGIS and User Manual VERSION
2 NOW AVAILABLE
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.
Distribution Map of Ohio Hemlock (ArcGIS shapefile created by Nicole Stump)
Maps of the Ridges Land Lab
Orthophotographs, historic air photos, land cover maps, trails & contour maps for Ohio University's Land Lab
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, most recently as part of an NSF-funded Appalachian Ohio Forest Research Group. 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. Feel free to contact me if you are interested in pursuing this research as a thesis topic, or if you are familiar with the herbaceous flora and would like to get involved with vegetation sampling.
Click here to view abstracts
Pederson, N., A.W. D'Amato, J.M. Dyer, D.R. Foster, D.
Goldblum, J.L. Hart, A.E. Hessl, L.R. Iverson, S.T.
Jackson, D. Mario-Benito, B.C. McCarthy, R.W. McEwan,
D.L. Mladenoff, A.J. Parker, B. Shuman, and J.W.
Williams. 2014. Climate remains an important driver of
post-European vegetation change in the eastern United
States. Global Change Biology, doi:
Pederson, N., J.M. Dyer, R. McEwan, A. Hessl, C. Mock, D. Orwig, H. Rieder, and B. Cook. 2014. The legacy of episodic climatic events in shaping temperate, broadleaf forests. Ecological Monographs 84(4): 599-620.
Anning, A., J.M. Dyer, and B.C. McCarthy. 2014. Tree growth response to fuel reduction treatments along a topographic moisture gradient in mixed-oak forests, Ohio, USA, Canadian Journal of Forest Research 44(5): 413-421.
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
Click here to view abstracts
Examining the Cover and Composition of
the Successional Vegetation Mosaic of Pre-SMCRA
Mined Landscapes in Southeast Ohio, Gary Conley, Geography
MS 2013. [Link
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). Download: zipped shapefile or jpeg of hemlock distribution in Ohio, methods and results of GIS mapping from thesis (PDF), PDF of 2009 HWA Summit presentation.
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
Landscape Suitability: A Case Study of Wolf Habitat in
Catastrophic Windthrow: A Case Study of the
A Spatial Analysis of an Urban Fishery: A Case Study of
|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 1100:||Physical Geography (fall semester)|
|GEOG 3160/5160 (BIOS 3160/5160):||Biogeography (spring semester of even years)|
|GEOG 4170/5170:||Landscape Ecology (spring semester of odd
Methods in Geography
|GEOG 5731:||GIS Applications
|GEOG 6160:||Seminar in Biogeography|