Eastern North Carolina chronosequence stands:
The ~85-year-old (NC_E 85yo),
~35-year-old (NC_E 35yo), and ~15-year
old (NC_E 15yo) eastern NC chronosequence stands were located in the
Blackwood Division of Duke Forest (35° 58’ 24.89”, -79° 6’ 1.55”). Mean
annual precipitation (1945–2015) for the area is 1144 ± 162 mm, with
619 ± 116 mm falling between April and September. Annual mean
temperature is 14.36 °C. NC_E 85yo was a naturally established stand
comprised of mixed hardwood species Q. alba , Quercus
michauxii Nutt., L. tulipifera , Liquidambar styracifluaL, and hickory species Carya tomentosa Sarg. and Carya
glabra Miller with a mean canopy height of 27.5 m (Oishi et al.,2010). NC_E 35yo was located less than 4 km from NC_E 85yo and was
part of the former Duke FACE project ambient plots. This site was
clear-cut in 1982 to remove a 50-year-old mixed pine forest and was
replanted in 1983. The stand was dominated by Pinus taeda L. butQ. alba , L. tulipifera, Acer rubrum L, L.
styraciflua, Cornus florida L. and Prunus serotina occurred in
the understory and stand gaps. Mean height of the mid-canopy Q.
alba and L. tulipifera trees in the NC_E 35yo stand was 15.1 m.
Soils were gravelly loam of the Iredell series with majority of the
rooting zone occurring at 45–65 cm depth (Domec et al., 2012).
A. saccharum trees were sampled in the NC_E chronosequence from
an additional lowland hardwood stand located 15 km from the ones
described above. Fagus grandifolia Ehrh. was the dominant canopy
tree species of this lowland hardwood site, but Q. alba , Q.
rubra , L. styraciflua , and A. saccharum occurred
frequently in the understory. This site was also part of the Duke Forest
but was characterized by a deep and well-drained soil with minimal
disturbance. The mean height of ~15 and
~35 years old A. saccharum trees were 9.2 and
19.5 m, respectively.