Mg. Ryan et al., WOODY-TISSUE RESPIRATION FOR SIMAROUBA-AMARA AND MINQUARTIA-GUIANENSIS, 2 TROPICAL WET FOREST TREES WITH DIFFERENT GROWTH HABITS, Oecologia, 100(3), 1994, pp. 213-220
We measured CO2 efflux from stems of two tropical wet forest trees, bo
th found in the canopy, but with very different growth habits. The spe
cies were Simarouba amara, a fast-growing species associated with gaps
in old-growth forest and abundant in secondary forest, and Minquartia
guianensis, a slow-growing species tolerant of low-light conditions i
n old-growth forest. Per unit of bole surface, CO2 efflux averaged 1.2
4 mu mol m(-2) s(-1) for Simarouba and 0.83 mu mol m(-2) s(-1) for Min
quartia. CO2 efflux was highly correlated with annual wood production
(r(2) = 0.65), but only weakly correlated with stem diameter (r(2) = 0
.22). We also partitioned the CO2 efflux into the functional component
s of construction and maintenance respiration. Construction respiratio
n was estimated from annual stem dry matter production and maintenance
respiration by subtracting construction respiration from the instanta
neous CO2 flux. Estimated maintenance respiration was linearly related
to sapwood volume (39.6 mu mol m(-3) s(-1) at 24.6 degrees C, r(2) =
0.58), with no difference in the rate for the two species. Maintenance
respiration per unit of sapwood volume for these tropical wet forest
trees was roughly twice that of temperate conifers. A model combining
construction and maintenance respiration estimated CO2 very well for t
hese species (r(2) = 0.85). For our sample, maintenance respiration wa
s 54% of the total CO2 efflux for Simarouba and 82% for Minquartia. Fo
r our sample, sapwood volume averaged 23% of stem volume when weighted
by tree size, or 40% with no size weighting. Using these fractions, a
nd a published estimate of aboveground dry-matter production, we estim
ate the annual. cost of woody tissue respiration for primary forest at
La Selva to be 220 or 350 g C m(-2) year(-1), depending on the assume
d sapwood volume. These costs are estimated to be less than 13% of the
gross production for the forest.