CTFS-ForestGEO: a worldwide network monitoring forests in an era of global change

Global change is impacting forests worldwide, threatening biodiversity and ecosystem services including climate regulation. Understanding how forests respond is critical to forest conservation and climate protection. This review describes an international network of 59 long-term forest dynamics research sites (CTFS-ForestGEO) useful for characterizing forest responses to global change. Within very large plots (median size 25 ha), all stems ≥1 cm diameter are identified to species, mapped, and regularly recensused according to standardized protocols. CTFS-ForestGEO spans 25°S–61°N latitude, is generally representative of the range of bioclimatic, edaphic, and topographic conditions experienced by forests worldwide, and is the only forest monitoring network that applies a standardized protocol to each of the world's major forest biomes. Supplementary standardized measurements at subsets of the sites provide additional information on plants, animals, and ecosystem and environmental variables. CTFS-ForestGEO sites are experiencing multifaceted anthropogenic global change pressures including warming (average 0.61 °C), changes in precipitation (up to ±30% change), atmospheric deposition of nitrogen and sulfur compounds (up to 3.8 g N m−2 yr−1 and 3.1 g S m−2 yr−1), and forest fragmentation in the surrounding landscape (up to 88% reduced tree cover within 5 km). The broad suite of measurements made at CTFS-ForestGEO sites makes it possible to investigate the complex ways in which global change is impacting forest dynamics. Ongoing research across the CTFS-ForestGEO network is yielding insights into how and why the forests are changing, and continued monitoring will provide vital contributions to understanding worldwide forest diversity and dynamics in an era of global change.We thank everyone involved in the collection of the vast quantity of data and information in the CTFS-ForestGEO network; to F. Dentener and W. Laurance for providing data; E. Leigh, Y. Lin, J. McGarvey and A. Miller for helpful comments; E. Aikens, L. Gonzalez and M. Azimi for help with analysis and figures. Study on this manuscript was funded in part by a Smithsonian Competitive Grants Program for Science award to KJAT. The CTFS-ForestGEO network has received major support from the Smithsonian Institution – particularly the Smithsonian Tropical Research Institute, the Arnold Arboretum of Harvard University, the National Science Foundation (multiple grants), the Rockefeller Foundation, the John Merck Fund, the John D. and Catherine T. MacArthur Foundation, the Andrew W. Mellon Foundation, the Frank Levinson Family Foundation, the HSBC Climate Partnership, the Bromley Charitable Trust, John Swire & Sons Pty Ltd, Celerity, F.H. Levinson Fund, Small World Institute Fund and Jennifer and Greg Johnson. Site-specific support is listed in Table S8