Response of forest tree seedlings to simulated litterfall damage

Litterfall is an important cause of seedling mortality in many forests ranging from wet tropical to boreal. However, there is a lack of studies that investigate differences between species in seedling resilience to litterfall damage. We selected seedling pairs of seven tree species and simulated litterfall damage by pinning one of each pair to the ground. The mortality and growth rates varied significantly between species for pinned individuals, but were similar for unpinned seedlings. The mortality of pinned Nestegis cunninghamii and Prumnopitys ferruginea was significantly greater than that of unpinned individuals (P < 0.05). However, contrary to expectations, the growth rates of pinned Hedycarya arborea and Nothofagus menziesii were much greater than for those left unpinned (P < 0.05). In general, seedling resilience to the bending damage differed substantially between species. N. cunninghamii and P. ferruginea suffered high mortalities and did not increase growth rates in response to damage, whereas, H. arborea and N. menziesii suffered few mortalities and regained height quickly. Other study species demonstrated intermediate resilience. This study demonstrates that some species are more likely to survive in high-risk litterfall regimes than are others. Given that litterfall risk can vary greatly between microsites, these results suggest that litterfall can contribute to regeneration niche differentiation.