Climate Change Across Seasons Experiment (CCASE) at the Hubbard Brook Experimental Forest; concentrations of foliar metabolites: polyamines, amino acids, chlorophyll, carotenoids, soluble proteins, soluble elements, sugars, and total nitrogen and carbon in red maple (Acer rubrum) trees.

Foliage was collected in 2015 and 2017 from red maple trees at the
Climate Change Across Seasons Experiment (CCASE) as part of the
Hubbard Brook Ecosystem Study (HBES). Analyses of foliar metabolites
include polyamines, amino acids, chlorophylls, carotenoids, soluble
proteins, soluble inorganic elements, sugars, and total nitrogen and
carbon. There are six (11 x 14m) plots in total in this study; two
control (plots 1 and 2), two warmed 5 degrees (°) Celsius (C) above
ambient throughout the growing season (plots 3 and 4), and two warmed
5 °C in the growing season, with snow removal during the winter to
induce soil freezing and then warmed with buried heating cables to
create a subsequent thaw (plots 5 and 6). Each soil freeze/thaw cycle
includes 72 hours of soil freezing followed by 72 hours of thaw. Four
kilometers (km) of heating cable are buried in the soil to warm these
four plots. Together, these treatments led to warmer growing season
soil temperatures and an increased frequency of soil freeze-thaw
cycles (FTCs) in winter. Our goal was to determine how these changes
in soil temperature affect foliar nitrogen (N) and carbon metabolism
of red maple trees.

These data were gathered as a collaborative effort at the Hubbard
Brook Experimental Forest, which is operated and maintained by the
USDA Forest Service, Northern Research Station.