Emergence and Survival of Three Native Grass Species Sown on Roadsides on the Northern Tablelands, New South Wales, Australia

Abstract

A field trial was set up to assess the emergence and survival under natural rainfall conditions of three species of native grasses when sown monthly for 8 months in seven different roadside environments. Generally, rainfall events of 40 mm or more were associated with substantial emergence events, and seed of Danthonia richardsonii cv. ‘Taranna’ and Microlaena stipoides was able to germinate after being in dry soil for up to 120 days. The highest emergence of Chloris truncata and ‘Taranna’ occurred from October and November sowings, whereas that of M. stipoides was from autumn sowings. For all species, emergence was highest in roadside environments with topsoil and poorest for a subsoil environment. Final percent survival of all species closely matched percent emergence with less than 20% seedling mortality occurring over time. A higher percentage of seeds sown in October and November germinated and survived as plants than from December and January sowings. Survival of plants from the initial seed source was generally greater than 25% for all species when sown between October and January. The highest seedling mortality occurred on an old road environment whereas the lowest was in a relatively undisturbed environment. Management implications are that on the Northern Tablelands, given adequate rainfall, these three native grasses have the best chance of successful establishment if sown in spring on a cultivated bed of topsoil. M. stipoides and D. richardsonii cv. ‘Taranna’ seed can also be sown into a dry seedbed in summer and germinate following rainfall several months later.