Abstract
Oak (Quercus) masting, the phenomenon in which reproduction is highly variable from year to year, is ecologically important, causing population shifts for diverse organisms within associated ecosystems. The resource dynamics underpinning this variable reproduction are still not fully understood, in part due to limited record lengths. Here, we use a 16-year acorn record to examine the relationship between growth and acorn production at the individual tree level for two species of oak, Quercus alba and Quercus velutina, in southern Indiana. We measured five growth variables: total ring width, latewood width, earlywood width, average earlywood vessel area, and number of earlywood vessels per ring. We correlated acorn production and growth variables with monthly maximum temperature, maximum vapor pressure deficit, and precipitation. Following that, using linear mixed effect models, we modeled growth (total ring and latewood width) using seasonal climate variables, acorn production, and individual tree random effects. Growth and acorn production responded to climate during different periods of time. At the population level, there were no strong relationships between growth and reproduction in either species. However, linear mixed-effects models incorporating individual tree random effects revealed some evidence of trade-offs between growth and reproduction in latewood width for Q. velutina, but not for Q. alba. This suggests divergent resource allocation strategies whereby Q. velutina reallocates resources from growth to reproduction, whereas Q. alba conserves resources across years for reproduction. Consequently, the term “masting” likely oversimplifies and obscures the varied reproductive behaviors even among species within the same genus.