Scaling from Leaves to Roots to Ecosystems and Landscapes

Fir needles

Scaling of respiratory metabolism to body size in animals is thought to be a fundamental law of nature, and considerable evidence has been reported for an approximate (3/4)-power relation. Some studies suggest that plant respiratory metabolism scales likewise, and that similar rules govern both higher plant and animal scaling. Although numerous theories have tried to explain universal scaling laws, they are all extremely controversial.

Our research suggests that plants and animals not only follow different metabolic scaling relationships, but also are driven by different mechanisms. We find that whole-plant respiration rates scale approximately isometrically in relation to total plant nitrogen (Reich et al. 2006, Nature), with no general relationship with plant mass, and the scaling is unaffected by light variation, nitrogen availability, temperature, and atmospheric [CO2]. However, before a general unifying allometric theory for plant biology can be accepted, much more work is needed. Moreover, recent work combining our plant data with data on numerous other taxa shows that there is no universal scaling law across the animal kingdom either, and instead, that there may be a relatively narrow range of metabolic rate across all life forms, suggesting some kind of metabolic optimum (Makarieva et al. 2008, PNAS).


Atkin, O.K., Bloomfield K.J., Reich P.B., Tjoelker M.G. et al.  2015. Global variability in leaf respiration among plant functional types in relation to climate and leaf traits. New Phytologist 206(2): 614-636.

Xiang, S., P.B. Reich, S. Sun, O. Atkin. 2013. Contrasting leaf trait scale relationships in tropical and temperate forest wet forest species.  Functional Ecology 27:522-534.

Makarieva, A.M., V.G. Gorshkov, B.-L. Li, S. L. Chown, P.B. Reich, V.M. Gavrilove. 2008. Mean mass-specific metabolic rates are strikingly similar across life’s major domains: Evidence for life’s metabolic optimum. Proceedings of the National Academy of Sciences 105:16994–16999.

Reich, P.B., M.G. Tjoelker, K.S. Pregitzer, I.J. Wright, J. Oleksyn, J.L. Machado. 2008. Scaling of Respiration to Nitrogen in Leaves, Stems, and Roots of Higher Land Plants. Ecology Letters 173(1):110-120.

Milla, R., P.B. Reich. 2007. The scaling of leaf area and mass: the cost of light interception increases with leaf size. Proc. Royal Society B 274:2109-2114.

Niklas, K. J., E. D. Cobb, U. Niinemets, P.B. Reich, A. Sellin, B. Shipley, I. J. Wright. 2007. ‘‘Diminishing returns’’ in the scaling of functional leaf traits across and within species groups. Proceedings of the National Academy of Sciences 104:8891-8896.

Reich, P.B., M.G. Tjoelker, J-L Machado, J. Oleksyn. 2006. Universal scaling of respiratory metabolism, size and nitrogen in plants.  Nature 439:1-8.

Reich, P.B. 2001. Body size, geometry, longevity and metabolism: do plant leaves behave like animal bodies?  Trends in Ecology and Evolution 16:674-680.