Does the exception prove the rule?

Abstract

Arising from: P. B. Reich, M. G. Tjoelker, J.-L. Machado & J. Oleksyn Nature 439, 457–461 (2006); Reich et al. reply, Hedin reply Reich et al.¹ report that the whole-plant respiration rate, R, in seedlings scales linearly with plant mass, M, so that when θ ≈ 1, in which c_R is the scaling normalization and θ is the scaling exponent. They also state that because nitrogen concentration (N) is correlated with c_R, variation in N is a better predictor of R than M would be. Reich et al. and Hedin² incorrectly claim that these “universal” findings question the central tenet of metabolic scaling theory, which they interpret as predicting θ = ¾, 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.