Diel patterns of stem CO efflux vary among cycads, arborescent monocots, and woody eudicots and gymnosperms.

The diel patterns of stem carbon dioxide efflux () were determined for cycads, monocots, and woody eudicot and gymnosperm tree species. Stem at a height of 30-40 cm was measured every 2 h throughout 31-h campaigns. Our range of was 1.5-4.0 µmol·m·s for cycads, 1.0-3.5 µmol·m·s for arborescent monocots, and 1.5-4.5 µmol·m·s for woody eudicot and gymnosperm trees species. Time of day did not influence of cycads or monocots. In contrast, the woody stems of eudicots and gymnosperms exhibited diurnal that was 36% to 40% greater than nocturnal . The established literature based on of woody tree species cannot be used to estimate habitat carbon cycles in habitats which contain cycad or monocot trees. Time of day must be included for accuracy of research on of woody tree species. Failures to account for the spatiotemporal differences of may explain some of the disparity in outcomes of published stem respiration studies.