A biological study of Durvillaea antarctica (Chamisso) Hariot and D ...

195
plants in adjacent control areas (Table 9.5) . Apparently stipe
length 'lias close to reaching a maximal value after 18 months, Itlhereas
stipe diameter would continue to increase for a longer period.
measurements or D, anta~otiaa
control areas.
in recolonising swards
Recolonising plants Control plants
Mean s length 15.9 ± 1.2 19,5 ± O.S Total sample
(cm) ± sy 32.2 :t 1.9 26,0 ± 0.8 Honeycombed only
Mean stipe dlam. 15.0 ± 1.1 22.3 ± 2.9 Total sample
{mml 26.0 ± 0.9 36.8 ± 1.9 Honeycombed only
At Tautuku, mean stipe weight increased exponentially to reach
a value of 312 9 in 30 months. Stipes of the largest plants weighed
1000-1250 g (Fig. 9.8). At Kean Point, mean stipe weight increased
exponentially throughout 1974 to reach a peak value of only 75 g, and
then declined. This was mainly due to a high mortality of large
plants during the autumn of 1975.
The stipe fraction of total plant weight increased rapidly in
both study areas to form approximately half the total wet weight in
less than a year. However, after about six months the laminae
began to grow at a. faster rate than stipes, and the stipe fraction
declined sharply (Figs. 9.9; 9.10).
(cl
Standing crop:
standing crop (expressed here as kg/m 2 ) of recolonising
swards soon exceeded the standing crop in adjacent control areas.
AI: Tautuku standing crop measurements in control areas rangeo from
18.8-33.0 kg/m 2 , whereas the standing crop of a two year old
recolonising sward on Area 1 reached a peak value of 72.5 kg/m 2 •
These high standing crop values were probably only a temporary feature
of recolonisiryg populations, however, for there is evidence of a
sharp de.ciine O.t both Tautuku and l