186
RECOVERY OF THE LAND PLANTS AT ENIWETOK ATOLL
schmidia (Fig. 5a) plants. On the thirty-fifth day
DISCUSSION
the shoot leaves were 7-15 cm long, covering
muchof the old stems (Fig. 5b) and giving the
plants a green and healthy appearance. By this
Previous studies to evaluate the recovery ar.
reinvasion of the flora at the Eniwetok Provir
Ground, approximately fifteen months aft
leaves and three species (Portulaca, Triumfetta,
St. JoHN@) and Bippuvpu.’® They reporte
morphological abnormalities in ten species «
time many of the other plants had formed new
and Messerschmidia) had produced new flowers
and fruits. The island now had lost its scorched
appearance; from the air it looked green rather
than brown as it had one monthearlier.
In August, three months after the detonation,
the plants were growing well (Fig. 6a) and some
species, such as Boerhaavia, had produced new
flowers. The leaves of most of the species had
grown to maximum size, and the branches had
grown almost to the pre-Nectar dimensions.
This was not the case with the Guettarda and
Operation Sandstone, were made in 1949 |
plants growing on islands where atomic detona
tions had taken place, and where radiatio:
levels were undoubtedly higher than those o1
Belle Island during the Nectar survey. Thes:
abnormalities included flattening, shortening
thickening and spiral torsion of stems, sever«
“die-back”’ of leaves and stems, chlorosis
asymmetry, shrivelling, crumpling and twisting
of leaves, chromatism of stems, proliferation and
enlargement of inflorescences, abnormal pro-
Lepturus plants, which recovered more slowly
than the other species. The new growth on the
liferation of stems, and sterility of plants. St.
john reported finding a mutant of Guettarda
which originated from a new shoot 18 cm tall
at the base of the old plant; the Lepiurus plant
was a mat of dead tops with some new growth
forming at the periphery.
Biddulph reported spiralling and splitting of
Guettarda plant consisted of ten small leaves
Spectosa on Runit Island but did not describeit.
fronds on several coconut palms on Aitsu (Olive)
Island, which is located between two of the
“shot” islands.
In six months the general condition of the
vegetation (Fig. 6b) was similar to that which
existed before the Nectar detonation, In March
On the “shot’’ islands, the plants closest to
the bomb crater centres (where radiation levels
were highest) were most severely affected. In
the plants appeared to be normal, most of them
bearing abundant flowers and fruits, healthy,
green leaves, and the usual amountof yellow,
older leaves. The Guettarda plant, however, bore
curled, distorted, and unhealthy-looking leaves
(Fig. 7a). When observed again in November
1955, it bore about thirty healthy, green leaves,
“disturbance of ecological habitats’ was reported to be more importantin excluding plants
from these areas than the radiation effects from
1955, approximately ten months post Nectar,
had increased in height and apparently was
completely recovered (Fig. 7b). The Portulaca
plant bore only a few leaves in March 1955, but
areas where radiation levels were lower, the
the
bombs.“
Undoubtedly many of the
abnormal plants started their growth after the
nuclear detonations had occurred in impoverished soil lacking morganic nutrients and
organic matter. These conditions are known to
cause nutrient deficiencies which can sometimes
be identified by the appearance ofthe plant. In
had
coral atolls where the top soil has been removed
the retention of rain water in the surface layer
of soil would beslight, resulting in the curling,
in the field observations at Belle Island. At
plants. On the basis of these observations it may
tumorous growths on plants of Ipomoea tuba
observed could have been caused by factors
other than radiation, Therefore, it would be
impossible to ascertain ajl of the causes of
damage to plants in an area where radiation
and nutrient deficiencies both exist. In areas of
when observed
in
November
1955,
it
recovered somewhat, bearing abundant flowers
and some green leaves.
No other aberrant growth forms were seen
janet Island,
the fasciated stems and
the
observed in 1949 by BrpputpH® were still
present in 1957.
The measurements and observations made on
one of the plants, Scaevola (No. 1319), during
the course of the study are presented in Table!.
drying, and ultimate death of the shallow-rooted
be concluded that some of the abnormalities
high radiation levels, much of this damage