Clearing the way: limited benefits of invasive tree removal for native saplings under browsing pressure in a Patagonian riparian ecosystem

Abstract Introduction Active restoration by planting with native woody saplings is recommended to improve passive restoration after removing invasive non‐native trees. However, this strategy could fail due to subsequent re‐invasions or ungulate presence, which could affect woody saplings. Objectives We assessed the effects of removing the invasive non‐native willow ( Salix × rubens ) on performance of planted saplings of this species and native willow ( Salix humboldtiana ) and chacay ( Ochetophila trinervis ) in a riparian ecosystem (NW Patagonia, Argentina). We also recorded browsing by ungulates. Methods We planted saplings in 10 plots invaded by willow (non‐removal treatment) and in 10 plots where willow was removed (removal treatment) and monitored their survival, growth, and browsing during three growing seasons. Results Survival of willow species was similar between treatments although their mortality was very high (>95%); whereas native chacay survival was lower in the willow removal treatment than in non‐removal. Height growth of native willow was lower in the removal treatment than non‐removal; whereas height growth of native chacay and non‐native willow was similar between treatments. In the removal treatment, native species were more browsed than non‐native willow; whereas in non‐removal plots, non‐native willow was more browsed than natives. Conclusions Therefore, non‐native willow removal did not enhance saplings' performance, particularly of native species, despite being heliophilous species that would benefit by increased light availability after willow removal. Furthermore, ungulates could contribute to the failure of active restoration by affecting species performance and influencing invasion processes through selective browsing. Non‐native willow did not survive, indicating a low re‐invasion probability.