does destroy life, and in this capacity 
we can define it as an unexpected 
increase in the probability of dying. 
But it is also intimately associated 
with the establishment of new indi- 
viduals. Destructive action creates 
space where there was none before, 
and in nature no space lies vacant 
for long. There are always species with 
subtle adaptations for recognizing 
those conditions favoring growth into 
the canopy foliage. 
Just how subtle these adaptations 
may be has been demonstrated by 
John Harper and his students at Uni- 
versity College of North Wales, who 
term such local disturbances safesites 
for seedlings. These investigators laid 
down a uniform garden seedbed in 
which they sowed seeds of three re- 
lated species of plantains — the great, 
the ribwort, and the hoary plantain 
— over the moist soil surface. To cre- 
ate microsite disturbances, they dug 
holes to different depths in the soil 
or left small, wooden boxes with their 
sides partly projecting above the sur- 
face or laid sheets of glass flat over 
the seeds. Two months of germination 
revealed obvious differences among 
the species. Few seedlings were found 
in control sites without any soil dis- 
turbance. The hoary plantain germi- 
nated vigorously under glass, probably 
because of the warmer temperatures 
and intense moisture. The great plan- 
tain was somewhat uncooperative, pre- 
ferring to appear in locations just out- 
side the local disturbances. The 
ribwort plantain favored boxes and 
deep holes. Most remarkable were two 
large clusters of ribwort seedlings vig- 
orously sprouting from a pair of earth- 
worm casts left at the surface. Un- 
doubtedly all these objects mimic the 
kind of natural microsite disturbances 
that favor the establishment of new 
individuals, and each species is 
adapted to slightly different circum- 
stances. 
This view of disturbance, scaled to 
relate to the biology of particular spe- 
cies, is a very different interpretation 
of nature from Clements’s view of sta- 
ble, permanent climax vegetation. 
Sudden and unpredictable upheavals 
are prevalent in nature, and the deaths 
of some individuals are soon followed 
by the establishment of others. From 
the perspective of the individual plant, 
the world appears closer to Turner’s 
vision. 
Robert E. Cook is associate professor 
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