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

Timing of spring leaf-out of red maple and sugar maple saplings experiencing combinations of soil warming and winter freeze-thaw cycles was assessed weekly in 2014 and 2015 from late April (when growing season warming began) through early June when leaves were fully expanded. 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.