To better understand the role that the world’s forests play in sequestering and releasing atmospheric carbon and how this process is linked to global climate change, the Smithsonian Tropical Research Institute Center for Tropical Forest Science is planning to expand the number of forest research plots it maintains around the world under its Global Earth Observatories program. The project is part of the HSBC Climate Partnership, a five year $100-million partnership between the Smithsonian Tropical Research Institute, the World Wildlife Fund, Earthwatch and the Climate Group.

At present, the Smithsonian maintains some 20 forest plots in 15 tropical countries in Latin America, Africa and Asia, and two plots in the temperate United States. Under this new initiative, the number of forest plots would be expanded by as many as 12 in five to 10 new countries. The Tropical Research Institute’s first large-scale forest research plot was established in 1980 on Barro Colorado Island in the Panama Canal. Every free-standing tree in this 120-acre area with a diameter at breast height of at least 1 centimeter was tagged, measured, mapped and identified by species. A census is conducted on the plot every five years. The sixth census was completed in 2006.

Despite a belief that rising amounts of atmospheric carbon dioxide being added to the atmosphere by human activity would have a growth-boosting “fertilizer effect” on tropical plants, studies of Global Earth Observatory forest plots in Panama and Malaysia have revealed a decrease in the growth rate of tropical trees in recent years. This findings suggests complex interactions between carbon dioxide enrichment, global temperature and tree growth, and offers a warning about the rate at which the world’s forests can absorb atmospheric carbon.

To fully assess the impact of global climate change on forests and the role that forests play in absorbing and holding carbon at local, regional and global scales, more Forest Dynamics Plots are needed in both tropical and temperate regions. Long term analysis of global forests can fill gaps in our knowledge, and data collected from the Global Earth Observatory network of forest plots will provide critical data for modeling carbon dynamics in the future. It also can provide a direct measurement of the effectiveness of efforts to reduce carbon emissions.