Spatial distribution of regeneration in mixed-species forests of Victoria

Summary

A study was carried out to describe the variation in the spatial distribution of regeneration in mixed-species forests of Victoria and examine its causes, as a basis for testing measures of regeneration success. Seedbed characteristics, stand history and spatial statistics based on quadrat counts and nearest-neighbour distances were determined for both intensively mapped stands and sparsely sampled coupes at case study sites. It was found that spatial distribution in stands established by clearfelling and artificial sowing, and by retention of seedtrees or shelterwood, were random to very aggregated.

Seedbed characteristics were the dominant factor contributing to seedling aggregation in high-elevation mixed-species forest. In low-elevation mixed-species forest the seedbed had an effect on aggregation, but the variation in seed supply also had a large influence on aggregation. Aggregation of regeneration within low-elevation mixed-species forest was not affected consistently by dominance class of the seedlings or the age of regeneration, but was affected by the source of regeneration (seedling or coppice). Aggregation of seedlings decreased or increased marginally with age in high-elevation mixed-species forest. There was variation in the degree of aggregation of different species in mixed-species stands, but there was a tendency for different species to occur together. It is recommended that further development of measures of regeneration success include a simulation study that tests measures with some proven performance in aggregated regeneration, and that the study should be on simulated stands that cover more than the full range of variation observed in the case study sites.

Keywords:

• mixed forests
• regeneration
• regeneration surveys
• stand density
• descriptors
• distribution
• occurrence
• layout
• standards
• methodology
• review
• Eucalyptus
• Victoria