Many countries have made commitments to restore huge areas of forest as part of the Bonn Challenge, organized by the International Union for Conservation of Nature. For example, Costa Rica has promised to preserve 1 million hectares (3,861 square miles) of forest by 2020—about 20 percent of the nation’s total area. However, a new paper in Conservation Letters suggests that quickly reforesting large areas may not be the best strategy to yield many of the benefits forests can provide.