Patterns in alpine seedling emergence and establishment across a stress gradient of mountain summits in south-eastern Australia

Abstract

Background: Past research and ecological theory supports the hypothesis that alpine plants should be predominantly clonal, long-lived and reproduce by seed infrequently.

Aims: To challenge the entrenched view that alpine seedling establishment is uncommon and perhaps unsuccessful in maintaining alpine plant populations.

Methods: We looked for patterns in seedling establishment across a stress gradient of alpine sites and tested the notion that natural seedling recruitment would be reduced at higher altitudes due to a combination of stressful environmental conditions such as frosts, wind and extended snow cover.

Results: Seedlings were common at all study sites and there was a partial trend in mean seedling density with altitude. Seedling emergence was best predicted by a combination of altitude, plant litter and soil wilting point. Many seedlings survived to become established plants (37–61%) but there was no significant relationship between establishment and altitude. There was low similarity between the seedling flora and the standing vegetation, suggesting that patterns in seedling establishment are unlikely to be driving the patterns in the standing vegetation assemblage.

Conclusions: Although Australian alpine species predominantly reproduce vegetatively, this study shows that many plants depend on recruitment from seed in order to become established.

Keywords:

• altitudinal gradients
• recruitment
• seedling similarity
• seedling survival
• seedlings

Acknowledgements

This research was conducted under Permit No. 10002497 (Department of Sustainability and Environment, Victoria). Susanna Venn was supported by an Australian Post-Graduate Research Award. Samantha Grover, Seraphina Cutler, Paul Smart, James Martindale Shannon, Elizabeth and John Venn and Nathan Wong helped undertake field work, often under trying conditions. Andrew Markwick (Parks Victoria) provided logistical support and encouragement. Samantha Grover helped with statistical analysis. Comments from Bob Parsons and three anonymous referees greatly improved the manuscript. The Holsworth Wildlife Research Fund, Australian Geographic Society, Ecological Society of Australia and the Department of Botany at La Trobe University provided financial support.