Recruitment of Eucalyptus strzeleckii (Myrtaceae) in intensive livestock production landscapes

Abstract

Eucalyptus strzeleckii K. Rule (Strzelecki gum) is a medium-to-tall forest swamp gum, endemic to Victoria and listed as Nationally Vulnerable in Australia. This species occurs in the high rainfall (up to 1600 mm) region of Gippsland in south-eastern Victoria. The region has been intensively developed for agriculture, in particular dairy production. Surviving trees are often old and in varying stages of dieback and natural recruitment is rarely observed. The removal of cattle-grazing as a sole mechanism to encourage recruitment is rarely sufficient to promote regeneration of this species. The aim of this study was to examine the role of soil disturbance, weed competition, seed supply and parent plant competition, in the absence of cattle-grazing, in the recruitment of E. strzeleckii. Seed availability, distance from mature tree, soil disturbance, soil moisture and pasture competition all influenced seedling establishment and survival in the field. Removal of ground layer vegetation immediately before seedling emergence appears to be essential for successful establishment of E. strzeleckii. However, both soil disturbance and pasture removal by spraying had similar effects, suggesting that competition rather than soil disturbance per se is a limiting factor in these environments. In the absence of understorey vegetation manipulation, regeneration by this species is unlikely even in the absence of grazing.