View article

Modeling and forecasting forests as carbon sinks require that we understand the primary factors affecting productivity. One factor thought to be positively related to stand productivity is the degree of asymmetry, or the slope of the relationship between tree size and biomass growth. Steeper slopes indicate disproportionate productivity of big trees relative to small trees. Theoretically, big trees outcompete smaller trees during favorable growth conditions because they maintain better access to light. For this reason, high productivity forests are expected to have asymmetric growth. However, empirical studies do not consistently support this expectation, and those that do are limited in spatial or temporal scope. Here, we analyze size–growth relationships from 1970 to 2011 across a diverse network of forest sites in the eastern United States (n = 16) to test whether asymmetry is consistently related to productivity …