The effect of logging on canopy nectar production in tall forest trees has for the first time been investigated by NSW DPI researchers, with funding from the Honeybee Program of the Rural Industries Research and Development Corporation and Forests NSW.
State forests provide the major honey resource for the beekeeping industry in NSW.
While Forests NSW has a number of management practices in place to retain nectar-producing trees during logging operations, there has been no information on how much nectar is produced by retained trees or young trees regrowing after logging.
Indeed, beekeepers have expressed concern about the effects of logging on nectar production, especially the perception that young trees do not produce as much nectar as mature trees.
The two eucalypt species chosen for research, Spotted Gum Corymbia maculata and Grey Ironbark Eucalyptus paniculata, are of prime importance to nectarfeeding wildlife, the timber industry and beekeepers.
Using cranes and cherry-pickers, flowers in forest canopies over 30 metres high on the NSW south coast were accessed. Nectar in flowers bagged overnight was measured to determine how much nectar they produce.
Both large and small trees were measured in forest with different logging histories: recently logged, regrowth and mature (more than 50 years since logging).
After measuring thousands of flowers, the study concluded that nectar production in Spotted Gum on a per flower basis was not affected by logging history nor tree size.
When the amount of nectar produced by whole forest stands is estimated on the basis of individual flower measurements and counts of flowers and trees, the study found that mature forest produced almost 10 times as much sugar per hectare as recently logged forest.
However, because current logging practices result in a mosaic landscape, where some areas are logged and others are left untouched, the impac
Contact: Joanne Finlay
New South Wales Department of Primary Industries