Relationships between Tree Cover and Grass Dominance in a Grazed Temperate Stringybark (Eucalyptus laevopinea) Open-Forest

Abstract

Dominance of herbaceous species was examined in relation to tree cover in lightly grazed stringybark Eucalyptus laevopinea open-forest recovering from ringbarking and logging on the Northern Tablelands of New South Wales (NSW). The dominant herb was recorded in 121 quadrats (0.25 m²) in 24 plots (10 × 10) stratified by tree cover (beneath trees, away from trees, and amongst small sapling stands). Aristida ramosa dominated the grassy understorey in interspaces, whereas Microlaena stipoides was the most frequent dominant beneath and near tree cover. Poa sieberiana was also more abundant beneath trees. Dominance varied in sapling stands between these three species, suggesting that tree invasion triggers herbaceous succession away from A. ramosa towards M. stipoides and P. sieberiana. It is suggested that year-long green, shade-tolerant grasses such as M. stipoides are better suited to the shaded, fertile, frost-protected environment beneath mature tree canopies, and deep-rooted, summer-active grasses such as A. ramosa are favoured away from the canopies and root zones of trees.