The trees that have grown in the cleared country generally have 
heavy branches and it is only in the steep ravines, in the residual forest 
or where a fence has allowed the development of a group of pines, that 
the trees show the branch-free stems recorded by the early settlers. 
Over the years trees have died apparently from old age and little 
concern was expressed by the islanders.  Seedlings have regenerated 
following the good seed years which occur every 4 to 6 years and there 
appears to be adequate replacement material if they are protected from 
grazing animals. There has been some planting on the forest reserves and 
common areas, however, little planting or encouragement of seedling 
regeneration has been carried out by private landholders. 
Approximately six years ago local people and visitors became con- 
cerned by the fact that significant areas of the island had no regener- 
ation and that many of the older trees, and some of the younger ones, were 
showing signs of ill health. The trees gradually developed thin crowns, 
sometimes produced secondary epicormic growth and eventually died. At no 
stage was there a dramatic loss of trees. 
A number of theories were advanced including infestation by a root- 
rotting fungus, Phythophthora einnamomi which was causing widespread 
damage in native eucalypt forests in Australia. It was also thought that 
the disorder might be similar to that affecting planted specimens of 
Norfolk Island pine in a number of oceanfront suburbs in Sydney on the 
east coast of Australia. 
Early in 1972 Heather (A.N.U. Dept For. pers. comm.) analysed samples 
of soil taken from beneath affected trees on the island. These were 
subjected to culture tests and examinations in an attempt to isolate the 
root-rot fungus. As only one of the 40 samples was found to contain 
Phythophthora cinnamomi this approach was considered inconclusive as an 
explanation of the disorder although it was accepted that the fungus was 
present on the island. 
At the same time the problem involving the dieback of pines in Sydney 
was being actively investigated. The symptoms were similar, however, 
in Sydney only coastal plantings were affected and specimens sheltered 
from the on-shore prevailing wind survived. On Norfolk, pines in the 
centre of the island were dying as well as some on exposed coastal sites. 
The Sydney disorder was reported by Hartigan (1970) and he concluded 
that the evidence pointed to some phytotoxic agent being carried by the 
wind onto the oceanfront trees. The investigation established that the 
disorder could not be attributed to overmaturity, disease, insects, soil 
impoverishment or lack of water. Later work by Hartigan (N.S.W. For. 
Comm. pers. comm.) and others identified the causal agent as the sus- 
pension in the aerosol of detergent particles from sewerage effluent 
emptied into the sea and swept back to shore by the prevailing winds. The 
detergent apparently dissolved the waxy layer on the scale-like leaves 
sufficiently to allow the salt in the spray to dessicate the leaf. The 
natural salt tolerance mechanism of the species was being broken down by 
the other components in the salt spray.