Recruitment Characteristics of the White Cypress Pine (Callitris Glaucophylla) in Arid South Australia.

Abstract

Callitris glaucophylla is a long lived tree which has had limited spasmodic recruitment in the South Australian arid zone in recent years. Domestic stock and rabbit grazing have been implicated as major factors limiting its regeneration. Factors influencing the recruitment and death of C. glaucophylla in the Roxby Downs region were investigated. The survivorship of C. glaucophylla seedlings, which germinated following flooding rains in March 1989, was monitored at three rabbit densities, with and without the protection of tree guards. Despite above average rainfall in 1989, all the monitored seedlings succumbed to desiccation within 18 months of germination. Grazing by rabbits had no impact upon regeneration. In an analogous study, the height distributions of young established C. glaucophylla groves were measured and used to assign groves to cohorts representing past recruitment events. Rainfall history was compared with the estimated age of C. glaucophylla stands. Successful regeneration of C. glaucophylla in the Roxby Downs region was dependent on uncommon prolonged periods of above average rainfall. Most successful C. glaucophylla recruitment occurred in distinct groves on deep sand.