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Assessing the risk of pollen-mediated gene flow from exotic Eucalyptus globulus plantations into native eucalypt populations of Australia

Barbour, RC, Otahal, Y, Vaillancourt, RE and Potts, BM 2008 , 'Assessing the risk of pollen-mediated gene flow from exotic Eucalyptus globulus plantations into native eucalypt populations of Australia' , Biological Conservation, vol. 141, no. 4 , pp. 896-907 , doi:

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Eucalyptus globulus is the most commonly planted hardwood species in industrial plantations
in Australia. It is typically planted well out of its natural range and may therefore
present a significant risk of exotic pollen-mediated gene flow into native eucalypt populations.
This risk was assessed by documenting levels of flowering within plantations, frequencies
at which reproductively compatible native species are found adjacent to
plantations, levels of F1 hybridisation with native populations, and the existence of F1
hybrid seedling recruitment. We surveyed over 300 plantations across southern Australia
over two years. Flower abundance was found to be low with an average of 3% of trees found
to flower on an inside row and 7% on the outside edge row of mature plantations. Considerable
variation in flowering was found between locations (0–20% of trees reproductive) and
52% of plantations did not have compatible native species growing adjacent. Consequently,
65% of reproductive age plantations presented minimal or low risk of hybridisation due to
lack of flowering and/or lack of adjacent compatible native species. Only three out of 10
surveyed high risk plantations were found to hybridise with native eucalypts (Eucalyptus
camaldulensis, 0–3% hybrids in open-pollinated seed; Eucalyptus ovata, 0–2%). Established
exotic E. ovata · globulus F1 hybrid seedlings were also identified at just one site, in response
to disturbance from fire. The potential for gene flow from E. globulus plantations into native
eucalypt populations does exist, however, the implementation of an outlined risk management
framework would greatly reduce the likelihood.

Item Type: Article
Authors/Creators:Barbour, RC and Otahal, Y and Vaillancourt, RE and Potts, BM
Keywords: Biological invasion Genetic pollution Genetic contamination Pollen dispersal Introgression Off-site impacts Forest management
Journal or Publication Title: Biological Conservation
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