The presence of bearded moss on many deteriorating trees was not 
considered to be a primary cause of decline. Work in the 1960s by Stahl 
(CSIRO D.F.R. pers. comm.) had indicated that the moss was non-parasitic 
and, along with many lichens, inhabited the bark of other species of trees 
and shrubs and fence posts. Several other species of Araucaria are often 
hosts to the bearded moss in their natural habitat (Paijmans 1976). 
Heavy infestations were apparent on very healthy trees in a commemorative 
avenue photographed over 70 years ago. Most of those trees were removed 
in 1940 to make way for the airstrip but they were still healthy at the 
time. The few remaining trees of the avenue were still healthy at the 
time of the survey. 
The deterioration of the pine in the older farmland areas was not a 
process which took place rapidly. Photographs taken 50 to 60 years before 
showed evidence of similar deterioration on individual crowns but no 
measure of the extent of the damage could be made. The disorder was 
clearly different from that existing in the Sydney area and foliar samples 
did not show any deficiencies or excessive concentrations of elements. 
The 48 soil samples collected in 1972 failed to produce any evidence of 
Phythophthora cinnamomi, however its existence on the island must be 
acknowledged. Since the decline was slow and the fungus very difficult to 
isolate from samples taken at the base of affected trees the connection 
between the two was not considered to be conclusive. 
Taking all evidence into account the study group advanced the opinion 
that the decline was brought about by a severe ecological upset resulting 
from some or all of the following: 
(i) severe competition from grasses and shrubs particularly on 
degraded and abandoned farmland; 
(ii) overgrazing and trampling by stock; 
(iii) severe nutrient deficiency on the old farmland. 
The relative significance of these factors varies from place to 
place and they are not listed in any order of priority (McArthur, Benson 
and Hartigan, 1972). 
One very obvious fact was that much of the severely affected dieback 
area was covered by a dense chaparral type of vegetation typified by red 
guava, Rhodomyrtus psidioides, wild olive, Olea africana, Hawaiian holly, 
Schinus terebinthifolius and lantana, Lantana camara. These species are 
capable of forming a very dense cover through which the pine cannot 
readily regenerate and which places enormous demands on the soil for 
nutrients and moisture. These species appear to make it much more dif- 
ficult for the pine to survive than did its rainforest associates. 
Competition from the imported grasses has increased with the recent 
spread of buffalo grass, Stenotaphrum secundatum and kikuyu grass, 
Pennisetum clandestinum, in addition to couch grass, Cynodon dactylon, 
which was introduced to the Island during the convict settlements. When 
ungrazed, the buffalo and kikuyu develop rank growth which prevents 
moisture from reaching the soil except during heavy rain. This severe 
competition could explain some of the serious difficulties being ex- 
perienced in attempts to establish pines at Headstone Point - one of the 
worst affected areas.