© 1996 Heron Publishing—Victoria, Canada
Estimates of net photosynthetic parameters for twelve tree species in mature forests of the southern Appalachians
N. H. Sullivan (1), P. V. Bolstad (2, 3) and J. M. Vose (4)
1. Department of Forestry, College of Forestry and Wildlife, Virginia Polytechnic Institute and State University, Blacksburg,
VA 24061, USA / 2. Department of Forest Resources, College of Natural Resources, University of Minnesota, 1530 North Cleveland Ave., St. Paul,
MN 55108, USA / 3. Author to whom correspondence should be addressed / 4. Coweeta Hydrologic Laboratory, Southeast Forest Experiment Station, U.S. Forest Service, Otto, NC 28763, USA / Received February 1, 1995
Summary
Leaf gas exchange, temperature, and incident radiation were measured in situ for 20 mature trees of 12 deciduous species spanning
a range of heights from 7.9 to 30.1 m and growing in the southern Appalachian Mountains. Air temperature, water vapor pressure,
total radiation, photosynthetically active radiation, and carbon dioxide concentration were also measured. Estimated mean,
light-saturated net assimilation rates (µmol m–2 s–1) were: Quercus coccinea Muenchh. (10.3), Q. prinus L. (9.9), Q. rubra L. (8.9), Betula lenta L. (8.1), Liriodendron tulipifera L. (7.9), Q. alba L. (7.6), Carya glabra Mill. (7.2), Acer rubrum L. (5.6), Nyssa sylvatica Marsh. (3.9), Cornus florida L. (3.5), and Acer pensylvanicum L. (1.7). There were significant differences in both net assimilation rates and quantum yield efficiencies between species,
with the understory species C. florida and A. pensylvanicum exhibiting lower net assimilation rates at saturation and higher estimated quantum yield efficiencies than the other species.
Average temperature and light decreased from the canopy top to bottom, whereas ambient CO2 concentration increased, and vapor pressure and vapor pressure deficits were inconsistent. We observed curvilinear effects
of temperature and vapor pressure deficit on net assimilation response to light, and these effects varied by species. Errors
in predicted net assimilation ranged from 1 to 3 µmol m–2 s–1 under the environmental conditions prevailing during the study.
Keywords:
Acer, Betula, Carya, Cornus, gas exchange, Liriodendron, net assimilation, Nyssa, quantum yield efficiency, Quercus, radiation, solar radiation, temperature.
