The researchers developed a new way to predict how much rainforest canopies catch, called the canopy interception index (CII). They used laser scanning to measure CII in different types of forests and compared it to other methods like leaf area and canopy height. The CII was found to be the most accurate at predicting rainfall interception, performing better than the other methods tested. This means that the CII can help us understand how forests interact with rainfall and improve our predictions of water cycling in forest ecosystems.