Regeneration of mountain ash following clearfelling of a regrowth stand.  R. G. Campbell and P. L. Bray.  May 1987.  40pp. (unpubl.)

SUMMARY

The aim of the study was to observe and understand the germination, survival and early growth of mountain ash (Eucalyptus regnans) over a range of seed-bed types and sowing treatments relevant to current practice for wood production from regrowth forests in the Central Highlands of Victoria. An operational regeneration coupe at Xylophone Bridge, Toolangi, was chosen for intensive study and a total of 78 experimental plots, each 4 m² in area, was established at seven selected locations (replications). Seed-bed types at each location included high intensity slash burn, moderate intensity slash burn and disturbed soil. Artificial sowing treatments included uncoated seed and coated seed sown in autumn of 1979, and uncoated seed sown in spring of 1979. Unsown control plots were also established. Germination, survival and growth were monitored on a fortnightly cycle during the first year, and intermittently thereafter.

Germination following hand sowing in mid-autumn occurred in late June and early July when winter conditions, including frost heave, were unfavourable for survival and growth. Germination of spring sown seed was largely delayed until autumn of the following year, and the survival and competitive position of resulting seedlings were extremely poor. A substantial fall of indigenous natural seed occurred at two of the seven locations, and significant numbers of seedlings were observed on unsown control plots at the other five locations. The survival and growth of these seedlings were generally superior to those originating from hand sown seed.

Ecosystem processes identified as being of key importance to the success of regeneration included:

1. germination in early autumn to optimize pre-winter growth and competitive position,
2. well established root systems and/or shelter to enable germinants to survive the rigorous conditions of the first winter, especially frost heave, and
3. rapid root development to optimize survival and competitive position during the first year of growth.

Opportunities for development action include:

1. sowing immediately after seed-bed preparation in late summer or early autumn,
2. seed-bed preparation aimed at the provision of a well distributed set of micro-environments favourable to early germination, survival and growth, and
3. seed-tree systems.

Each of these practices has the potential to substantially reduce the high cost of seed supply for regeneration by direct seeding and it is strongly recommended that further research and development action should be initiated to evaluate this potential under operational conditions.

Germination surveys of the type used in the present study offer a simple technique for prediction of the success or failure of regeneration in late winter of the first year in time for rehabilitation action without the loss of a season or the need for further expensive site preparation. In addition, they provide direct feed-back to field personnel which can be used to motivate and guide the ongoing improvement of their seed supply, seed-bed preparation and sowing activities. Hence, it is strongly recommended that they be used as a basis for integrated development action within the Regional Management Systems responsible for the regeneration of mountain ash forests.