© 1996 Heron Publishing—Victoria, Canada
Stem respiration in a closed-canopy upland oak forest
Nelson T. Edwards and Paul J. Hanson
Oak Ridge National Laboratory, Environmental Sciences Division, Oak Ridge, TN 37831-6034, USA / Received March 8, 1995
Summary
Stem respiration was measured throughout 1993 on 56 mature trees of three species (Quercus alba L., Quercus prinus L., and Acer rubrum L.) in Walker Branch Watershed, Oak Ridge, Tennessee. A subset of the trees was remeasured during 1994. Diameter increments,
stem temperatures and soil water were also monitored. Respiration rates in the spring and summer of 1993 tracked growth rate
increments, except during a drought when growth dropped to zero and respiration increased to its highest rate. During the
dormant season, rates of total stem respiration (Rt) tended to be greater in large trees with thick sapwood but no such trend was observed during the growing season. Before
and after the growing season, respiration rates correlated well with stem temperatures. Estimated values of Q10 were 2.4 for the two oak species and 1.7 for red maple. The Q10 values were used along with baseline respiration measurements and stem temperatures to predict seasonal changes in maintenance
respiration (Rm). In red maple, annual total Rm accounted for 56 and 60% of Rt in 1993 and 1994, respectively. In chestnut oak, Rm accounted for 65 and 58% of Rt in 1993 and 1994, respectively. In white oak, Rm accounted for 47 and 53% of Rt in 1993 and 1994, respectively. Extrapolating these data to the stand level showed that woody tissue respiration accounted
for 149 and 204 g C m–2 soil surface year–1 in 1993 and 1994, respectively.
Keywords:
Acer rubrum, carbon cycling, growth respiration, maintenance respiration, Quercus alba, Quercus prinus, tree respiration.
