
Research topics: Biology of Frankia, a nitrogen-fixing actinomycete, and physiological plant ecology with emphasis on nitrogen fixing and wetland plants
Research program: My main research interests lie at the interface between physiology of plants and the kinds of environments in which they occur. Topics that are of special interest to me include the physiological ecology of actinorhizal nitrogen-fixing plants, physiological ecology of peatland plants, plant energy budgets, and physiological ecology of seed germination. Most of my current work concerns the physiology and ecology of actinorhizal plants. These plants are woody dicots that form nitrogen-fixing root nodules with Frankia, an actinomycete. They are found in 23 genera in 8 families and include alders (Alnus spp.), sweet gale (Myrica gale), bayberry (Myrica pensylvanica), and sweet fern (Comptonia peregrina). Actinorhizal plants commonly grow vigorously in nitrogen-poor soils where most plants grow only poorly or not at all. Such soils include raw mineral soils, sandy soils found on glacial outwash plains and along shores, and wet soils along streams and shores and in swamps and peatlands. Projects presently underway are examining the role that hemoglobin plays in Frankia including its localization within the cell and its interaction with oxygen. In addition we are examining the conditions needed for seedling establishment in common Maine actinorhizal plants.
Selected Publications
Tjepkema, J.D., Cashon, R.E., Beckwith, J., and Schwintzer, C.R. 2002. Hemoglobin in Frankia, a nitrogen-fixing actinomycete. Applied and Environmental Microbiology 68: 2629-2631.
Schwintzer, C.R. and Tjepkema, J.D. 2001. Effect of elevated carbon dioxide in the root atmosphere on nitrogenase activity in three actinorhizal plants. Canadian Journal of Botany 79: 1010-1018.
Tjepkema, J.D., Schwintzer, C.R., Burris, R.H., Johnson, G.V., and Silvester, W.B. 2000. Natural abundance of 15N in actinorhizal plants and nodules. Plant and Soil 219: 285-289.
Dow, M.A. and Schwintzer, C.R. 1999. Seed germination, seedling emergence, and seed bank ecology of sweet-fern (Comptonia peregrina (L.) Coult.). Canadian Journal of Botany 77: 1378-1386.
Barkmann, J. and Schwintzer, C.R. 1998. Rapid N2 Fixation in Pines? - Results of a Maine Field Study. Ecology 79: 1453-1457.
Other publications from this laboratory