Our modelling results demonstrate a mechanism by which natural
stands can withstand more severe drought than pine plantations,
based on greater safety margins between soil water
potential and critical transpiration rates (Fig. 8). Regardless of the
soil type, plantations had a marginal safety factor suggesting that
they operated at xylem tensions closed to xylem tensions capable
of inducing total hydraulic dysfunction. This result is in disagreement
with recent studies looking at inter-species resistance to
drought that predicted higher rates of hydraulic dysfunctions in
angiosperms as opposed to conifers (Choat et al., 2012) but is consistent
with others showing that pines can be very vulnerable to
drought (Hacke et al., 2000; McDowell et al., 2013).