Spontaneous and assisted restoration of vegetation on the bottom of a former water reservoir, the Elwha River, Olympic National Park, WA, U.S.A.

Spontaneous vegetation restoration on fine sediments of the drained Elwha River reservoir closely mirrors adjacent natural forests, suggesting rapid and effective ecological recovery without human intervention. This study found that substrate texture—fine versus coarse sediments—was the primary factor influencing plant community composition, with successional age and proximity to existing forests also playing significant roles. Assisted restoration techniques like planting or seeding showed no discernible benefit in accelerating native vegetation development on fine sediments. Invasive species were notably less abundant than anticipated, indicating a resilient recovery process. These findings highlight the potential for spontaneous succession in post-dam removal landscapes, particularly on finer substrates, while suggesting that active intervention may be necessary to enhance native plant communities on coarser sediments.

Prach, K., Chenoweth, J., & del Moral, R. (2019). Spontaneous and assisted restoration of vegetation on the bottom of a former water reservoir, the Elwha River, Olympic National Park, WA, U.S.A. Restoration Ecology, 27(3), 592–599. Portico. https://doi.org/10.1111/rec.12915