Plant Physiological Ecology
Howard S. Neufeld
Professor
Ph.D., University of Georgia
Postdoctoral, New Mexico State University and
U.S. Environmental Protection Agency, Corvallis, Oregon
For more information, see My Webpage
Research in my laboratory is focused on the physiological ecology of plants, including such topics as water relations and gas exchange patterns, air pollution, and the ecology of invasive plants. In recent years we have had a large research effort geared towards understanding the impacts of tropospheric ozone on plants native to Great Smoky Mountains National Park. We have identified nearly 100 species in the Park that show foliar symptoms in the field consistent with ozone exposure, which is around 6% of the Park flora. Using exposure chambers, we have found a variety of species that are sensitive to elevated ozone (early successional species in particular) but surprisingly, most plants show no adverse symptoms except at ozone exposures well above ambient, indicating that current ozone levels may not be that damaging. There are exceptions, however. Both tall milkweed ( Asclepias exaltata ) and cutleaf coneflower ( Rudbeckia laciniata ) show severe foliar injury at ambient levels of ozone, and the milkweed prematurely loses its leaves by mid-August. We are currently funded by the National Park Service to continue our wildflower studies, as well as to look at the responses of mature trees in the field to ozone.
A sampling of my current and recent students' Masters projects includes work on the water relations and ecophysiology of an understory evergreen herb, Galax urceoloata ; effects of grazing in wetlands adjacent to the Blue Ridge Parkway, responses of tall milkweed and cutleaf coneflower to ozone, vegetative recovery following fire in the Linville Gorge Wilderness Area, the ecophysiological adaptations that allow Galax leaves to persist through the winter, water relations of cutleaf coneflower plants, and the anatomical characteristics of species sensitive to ozone in the Smokies. Earlier projects have included studies of sunfleck responses in the invasive C4 grass Microstegium vimineum , the reproductive and population ecology of M. vimineum , cadmium tolerance in cypress trees ( Taxodium distichum ) and the impacts of ozone on many tree species, as well as acid rain impacts on red spruce ( Picea rubens ).
Students in my lab develop skills in ecophysiology such as gas exchange and plant water relations techniques, as well as gaining expertise in the basic aspects of plant ecology research. Most of the Masters theses out of my lab combine laboratory and field work, and include both observational and experimental methodologies. Some of my students go on for their Ph.Ds., while others obtain positions as community college instructors, technicians in research labs, Peace Corps volunteers, and environmental consultants.
Model of phenology for an evergreen plant as a function of latitude. Dashed and dotted lines represent changes in date of last frost in spring and first frost in fall. Short dashed lines represent dates when canopies are fully leafed out or fully leafless. Gray areas represent photosynthetic activity of evergreen herbs; width of gray area is proportional to activity. As latitude increases, the period for favorable carbon gain is shifted more toward the summer, and time available to take advantage of high light in spring and fall is greatly reduced. From Neufeld and Young (2003).
Selected Publications
Neufeld, H.S., Lee, E.H., Renfro, J.R., Hacker, W.D., and Yu, B. (1995) Sensitivity of seedlings of black cherry ( Prunus serotina Ehrh.) to ozone in Great Smoky Mountains National Park. 1. Exposure-response curves for biomass. New Phytologist 130:447-459.
Horton, J.L., and Neufeld, H.S. (1998) Photosynthetic responses of Microstegium vimineum (Trin.) A. Camus, a shade-tolerant, C4 grass, to variable light environments. Oecologia 114:11-19.
Neufeld, H.S., Lee, E.H., Renfro, J.R., and Hacker, W.D. (2000) Seedling insensitivity to ozone for three conifer species native to Great Smoky Mountains National Park. Environmental Pollution 108:141-151.
Chappelka, A.H., H.S. Neufeld, A.W. Davison and G.L. Somers. (2003) Evaluation of ozone injury on foliage of cutleaf coneflower ( Rudbeckia laciniata ) and crownbeard ( Verbesina occidentalis ) in Great Smoky Mountains National Park. Environmental Pollution 125:53-59.
Davison, A.W., H.S. Neufeld, A.H. Chappelka, Kirsten Wolff and P.L. Finkelstein. (2003) Interpreting spatial variation in ozone symptoms shown by cutleaf coneflower, Rudbeckia laciniata L. Environmental Pollution 125:61-70.
Neufeld, Howard S. and Donald R. Young. (2003). Ecophysiology of the herbaceous layer in temperate deciduous forests. In: Gilliam, F. and M. Roberts, eds. The Herbaceous Layer in Forests of Eastern North America, Oxford University Press, Oxford, UK. pp. 38-90.
Back to Top
|
