Climate Change Across Seasons Experiment (CCASE) Sapling Study at the Hubbard Brook Experimental Forest: Photosynthesis

Rates of leaf-level photosynthesis of red maple and sugar maple saplings experiencing combinations of soil warming and winter freeze-thaw cycles was measured biweekly on fully expanded, intact leaves from June through August 2014 and June through September 2015 using a LI-6400. There were seven treatments for each species of maple. For each species, ten saplings experienced ambient temperatures (reference), ten experienced growing season warming with no induced freeze-thaw cycles in winter (warmed), ten in each of four groups experienced warming in the growing season coupled with two, four, six, or eight soil freeze-thaw cycles in winter (warmed + 2 FTC, warmed + 4 FTC, warmed + 6 FTC, warmed + 8 FTC), and ten experienced snow removal in winter with ambient temperatures in the growing-season (snow removal). These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.