Forest leaf area is a critical link between the carbon, water and energy cycles of the biota and those of the atmosphere, and its growing-season dynamics are the focus of increasing interest. In this study Jin et al. combine use litter traps and an optical instrument to estimate of leaf area index (LAI) in a Pinus koraiensis forest. They examine how LAI changes throughout the growing season, comparing methods and accounting for foliage clumping. This work will inform ongoing efforts to measure and understand canopy phenology in a changing climate.