The Gs-ref of all species at all locations
and both measurement periods increased proportionally with
Ktree (Fig. 2). There was no difference in the relationship between
Gs-ref and Ktree for trees growing in the natural stands (P = 0.56)
and in the plantations. Overall, as Ktree increased by 50% from minimum,
Gs-ref increased by 42% to 47% (Fig. 2). Species differences
were apparent in Ktree, with higher values in N. sylvatica at the
coastal site and in L. tulipifera and Carya tomentosa at the
Piedmont site.