Survivorship
Despite experiencing extreme thermal anomalies and grazing rates at the
start of the experiment, cool-warm transplants displayed high
survivorship (number of surviving rhizome fragments) with no significant
differences observed between treatments at the end of the thermal stress
period (χ2 = 10.65, df = 5, p = 0.06, Fig. 3).
Survivorship then declined in all treatments over winter months (between
October and April), potentially due to dislodgement from storms. Notably
however, both centre-centre and centre-warm treatments displayed
significantly lower survivorship than all cool-edge and warm-edge
populations by the end of the experiment (χ2= 58.07,
df = 5, p<0.001, Fig. 3A).
The number of living shoots per fragment of rhizome was relatively
stable over time, with slight declines over the period of thermal stress
(Fig. 3B). Warm-warm and cool-centre treatments displayed significantly
lower rates of shoot mortality than central and other cool-edge
treatments at the end of the thermal stress period (ANOVA,
F(5,388) = 8.118, p <0.001). By the end of the
recovery period, changes in shoot numbers on the surviving fragments had
stabilised and cool-centre fragments had recovered to display no net
change from the beginning of the experiment.