A new study published in Nature Ecology and Evolution finds that larger, continuous forests absorb carbon far more efficiently than fragmented patches of the same total area. Researchers analyzed satellite data across 17 million forest patches in the United States and found that a hectare in a large forest was 38% more productive than an isolated hectare. This fragmentation costs the U.S. roughly 160 million metric tons of carbon absorption per year. The effect is driven by edge effects, where trees at forest boundaries face more stress from wind, temperature shifts, and direct sunlight, reducing their ability to photosynthesize and store carbon. The pattern was also observed on other continents and was especially strong in tropical regions. The findings challenge net zero deforestation policies that simply replace cleared forest area elsewhere, as the carbon benefit of replacement forests is lower than that of intact large forests.
