AERIAL ASSESSMENT OF DIEBACK OF 
NORFOLK ISLAND PINE (ARAUCARIA 
HETEROPHYLEA) IN ITS NATURAL 
ENVIRONMENT 
M.L. Benson and B.J. Myers 
Division of Forest Research, CSIRO 
Canberra, A.C.T. Australia 
SUMMARY 
Norfolk Island pine, Araucaria heterophylla, is a species of con- 
siderable interest in horticultural and wood production plantings through- 
out the world and has been grown successfully on a wide range of soil 
types in a variety of temperate and sub-tropical maritime climates. The 
species is extremely tolerant to salt and wind but has been reported to 
suffer badly in a polluted atmosphere where its salt tolerance mechanism 
has been adversely affected by detergents in the aerosol. 
Concern has been expressed in recent years over the number of Norfolk 
Island pines showing crown deterioration and ultimate death in its natural 
environment - an isolated small island in the South Pacific Ocean of great 
conservation and tourist value. An investigation of the problem was aided 
by large-scale colour aerial photography taken for a detailed vegetation 
survey and by supplementary oblique colour photography taken some 6 years 
later. The occurrence of the damage was mapped and more than 25% of the 
island showed at least some signs of deterioration with half of this area 
being severely affected. 
Through correlation with the history of land use and development 
activities, coupled with site investigation and soil sampling, the problem 
was identified as the result of severe ecological disturbance. Causes 
advanced were overgrazing, nutrient depletion on colonised farmland, and 
severe competition from imported grasses and shrubs. 
The worst affected areas were those having the longest association 
with human habitation. 
  
Keywords : Colour aerial photography, ecological damage, dieback