Variation in foliar respiration and wood CO2 efflux rates among species and canopy layers in a wet tropical forest

• DOI: 10.1093/treephys/tpu107
• Publication Date: 2015-01-19T01:12:25Z
• Authors: S. Asao; R. Bedoya-Arrieta; M. G. Ryan
• Keywords: Understory; Photosynthetic capacity; Tree canopy; Soil respiration; Ecosystem respiration

As tropical forests respond to environmental change, autotrophic respiration may consume a greater proportion of carbon fixed in photosynthesis at the expense growth, potentially turning into source. Predicting such response requires that we measure and place complete budget, but extrapolating measurements from chambers ecosystem remains challenge. High plant species diversity complex canopy structure cause rates vary do not account for this complexity introduce bias extrapolation more detrimental than uncertainty. Using experimental plantations four native tree with two layers, examined whether layers foliar wood CO2 efflux variation relates commonly used scalars mass, nitrogen (N), photosynthetic capacity size. Foliar rate varied threefold between ∼0.74 μmol m−2 s−1 overstory ∼0.25 understory, little among species. Leaf mass per area, N explained some variation, height more. Chamber thus can be extrapolated leaf area specific each layer or class. If area-based are sampled across regressed against derive slope (per rate) extrapolate using total mass. Wood 1.0–1.6 trees 0.6–0.9 understory The was mostly related size, species, height. Mean surface derived by regressing ratio stand area. temperature similar three wet dry seasons. For these forest, vertical sampling yield accurate estimates would temporal sampling.