the plantations were more vulnerable (P < 0.01) than roots from
natural stands. For branches, values of P50 at the coastal site ranged
from –1.4 MPa in N. sylvatica to 3.0 MPa in P. taeda. Conversely,
root P50 ranged from 0.70 MPa for P. taeda to 1.30 MPa in N. sylvatica.
At the Piedmont sites, P50 of branches varied from 1.5 MPa
in Q. velutina to 3.8 MPa in P. taeda and L. tulipifera. For roots, L.
styraciflua and P. taeda have the least negative P50 values of around
0.95 MPa and L. tulipifera the most negative at –2.1 MPa.
3.2.