The effect of airborne salt deposition on Acacia regeneration North Keppel Island.

Abstract

The importance of airborne salt deposition in limiting /Accacia regeneration on North Keppel island was first proposed by Brennan (1986). Observations of Acacia distribution and Health tended to support this idea. In the salt exposed areas /Accacia species were severely stunted and displayed a phyllode tip necrosis. Airborne salt deposition was monitored throughout the grassland and forest zone. "Seedling' development and symptoms 'were recorded at the various degrees of salt exposure. It was shown that actual salt deposition is a product of two interactive exposures, topographical and biological. 'Topographical exposure being based on the proximity to the sea and the extent of natural barriers. Biological exposure involves the general plant community and the degree of sheltering it offers. Acacia "seedling' development under these parameters is significantly reduced in the topographically exposed hilltop sites. Within the less •exposed gully site, there is little evidence of airborne salt deposition restricting regeneration success. An investigation into other possible stresses was also (undertaken. It was shown that soil nutrients were an important limitation to development. However soil salinity was seen to be of minor importance.