Origin of planted Eucalyptus benthamii trees in Camden NSW: checking the effectiveness of circa situm conservation measures using molecular markers.

Eucalyptus benthamii is a threatened species with a restricted range to the southwest of Sydney, Australia. One extant subpopulation is relatively secure within a closed water catchment in the Kedumba Valley. However, the other main subpopulation, which once probably had a more-extensive distribution along the Nepean River, is now fragmented due to clearing for agriculture and urban development. This has impacted on reproductive success and recruitment. Planting of trees in urbanised areas and other locations along the Nepean River has been ongoing for over 20 years and is an important circa situm conservation measure. Government policy has been to plant trees that are of local provenance, however it is difficult to know whether this policy has been properly implemented: it is possible that planting stock may have been sourced from the Kedumba subpopulation. Microsatellite markers were used to examine the probable origins and kinship of 133 planted trees from 15 planted sites around Camden, NSW. Population assignment confirmed that the majority of planted trees are probably from the local Nepean River subpopulation, although some were identified that are very likely to have originated from the Kedumba Valley. While the overall diversity of the planted trees is high, kinship within individual planted stands is often elevated, increasing the potential for inbreeding and limiting their usefulness as seed sources. This probably reflects seed sourced from a narrow genetic base. We discuss the findings and their implications in the context of the species' management and conservation strategy. [ABSTRACT FROM AUTHOR]