Lianas are an important component of tropical forests where they reduce tree growth fecundity and survival. Competition for light from lianas may be intense; however the amount of light that lianas intercept is poorly understood. We used a large-scale liana-removal experiment to quantify light interception by lianas in a Panamanian secondary forest. We measured the change in plant area index (PAI) and forest structure before and after cutting lianas (for 4 yr) in eight 80 m × 80 m plots and eight control plots (16 plots total). We used ground-based LiDAR to measure the 3-dimensional canopy structure before cutting lianas and then annually for 2 yr afterwards. Six weeks after cutting lianas mean plot PAI was 20% higher in control vs. liana removal plots. One yr after cutting lianas mean plot PAI was