Biological scaling: Does the exception prove the rule?
Arising from P. B. Reigh, M. G. Tjoelker, J.-L. Machado & J. Oleksyn Nature 439, 457-461 (2006)10.1038/nature04282; Reich et al. reply, Hedin reply
Reich et al. report that the whole-plant respiration rate, R, in seedlings scales linearly with plant mass, M, so that R = cRMθ when θ ≈ 1 in which cR is the scaling normalization and θ is the scaling exponent. They also state that because nitrogen concentration (N) is correlated with cR, variation in N is a better predictor of R than M would be. Reich et al. and Hedin incorrectly claim that these "universal" findings question the central tenet of metabolic scaling theory, which they interpret as predicting θ = 3/4, irrespective of the size of the plant. Here we show that these conclusions misrepresent metabolic scaling theory and that their results are actually consistent with this theory.