Reproductive versus vegetative recruitment of the invasive tree Schinus terebenthifolius: implications for restoration on Reunion island.

Knowledge of propagation mechanisms is important for understanding the invasion ecology and management of invasive plants in order to restore invaded lands. The identification of recruitment pathways is one of the keys to understanding dispersal mechanisms and determining invasive plant control strategies. The objective of this study was to characterize the recruitment processes of Schinus terebenthifolius, one of the most serious plant invaders in Reunion Island's lowlands. Surprisingly, little attention was given in literature to vegetative propagation by suckering as a dispersal mechanism. Yet, field observations on abandoned farmland and riverbanks combined with germination experiments have shown major differences in recruitment patterns between wet and dry areas. On abandoned dryland farms, seedling emergence is 35 times less than on riverbanks and is replaced by suckering. Birds facilitated seed germination, but their role in seed dispersal (ornithochory) appeared minor and restricted to the formation of satellite invasion foci. Water movement appears to be a more efficient vector than ornithochory because it aids seed transportation (hydrochory), seed germination, and suckering on riverbanks. Control and restoration programs must distinguish the two kinds of recruitment that impact on short- and long-distance dispersal