Naturally Regrowing Eucalypts Is a Challenge

Article excerpt

Large areas of Australia's grazing lands now need restocking with native vegetation in order to restore the integrity of the landscape and recharge ecosystems. But while 'natural regeneration' of eucalypts is typically relatively cheap for farmers compared with direct seeding or planting tubes, research shows that natural regeneration is fickle and can involve some risk in the allocation of resources to it.

The successful establishment of new woodland eucalypt saplings occurs infrequently and under limited circumstances. It requires a number of favourable conditions--high seedfall, gaps in pasture, good germination rains, low competition from pasture, a wet summer and freedom from grazing. The process can be, and often is, prevented by any of these conditions failing to occur. Success therefore may largely boil down to time, patience, and resisting the urge to let heavy-grazing livestock back onto regenerating areas in harder times.

University of Melbourne researcher Peter Vesk, co-author of a natural regeneration paper recently appearing in the Australian Journal of Botany, said research indicated eucalypt regeneration was likely to be episodic rather than annual, no matter what a manager did to prepare their land. Vagaries of weather, seed supply and seedling survival were a key part of the reason.

Along with Josh Dorrough, a researcher at Victoria's Arthur Rylah Institute for Environmental Research, Vesk has shown that in any given year, natural regeneration may not be successful because the probability of having everything go right is low.

'Natural regeneration might work very well in time, but actually managing [land] for it to occur is going to be risky, given that we might do all we like and often not get the response we're after,' Vesk said.

Regional incentives schemes designed to foster natural regeneration therefore needed to accommodate this uncertainty, he said.

Such schemes typically invited landholders to enter into contracts to manage land parcels in a certain way for a number of years. Vesk said schemes based around longer periods were going to be more useful for exploiting the potential offered by natural regeneration.

The researchers presented a model that brings together three sorts of natural regeneration information available: relatively small-scale experiments 'that ecologists love to do'; broader-scale survey studies; and expert information held in the minds of people who had worked on the land, in some cases for decades. …