Stream running through a forest
Riparian Restoration

 

Riparian ecosystems are found along rivers and streams. These include perennial waterways that have a continuous flow of water year-round and ephemeral systems that typically only flow during certain times of the year (e.g., the rainy season or following snowmelt). Riparian plant communities are found across California’s diverse ecosystem types, from the mountains and deserts to the coasts. These systems provide critical ecosystem services including erosion control, flood regulation, water quality improvement, groundwater recharge, and wildlife habitat [1]. Heavily impacted by development, water diversion and extraction, agriculture, logging, invasive species, eutrophication, and pollutants, there is a strong need for restoration and management of riparian ecosystems.

Restoring riparian ecosystems is challenging and typically requires a combination of strategies, including re-establishing natural hydrology, controlling erosion, stabilizing stream banks, and the reestablishment of native vegetation [2]. Obtaining the proper permitting is essential for riparian restoration in California to ensure that management interventions are implemented in accordance with state and federal regulations. In severely altered waterways, re-establishing natural hydrology through the removal of barriers and the restoration of stream channels may be required. Preventing erosion is a high priority for any riparian restoration project. This can be accomplished through contouring or terracing streamsides, mulching treatments, barriers (e.g., silt fences), and ultimately, revegetation.

Passive restoration may be an effective approach for revegetation in some riparian habitats [3]. In this approach, disturbances or stressors (e.g., grazing or invasive species) are removed, and native vegetation recovers through natural recruitment. In more disturbed sites, active revegetation may be required to meet project goals through seeding, transplanting, or cuttings [2]. Many woody plant species that are adapted to riparian habitats can be propagated from cuttings, which can be planted directly into the restoration site for rapid plant establishment [4]. Using a diversity of species with varying growth forms, rooting structures, and phenologies can enhance ecosystem resilience and enhance wildlife habitat. Understory species may have low light tolerance, and waiting to introduce these until woody species have developed a canopy may improve their establishment [5]. Ongoing control of invasive species is often necessary to ensure the success of revegetation efforts [6]. This may involve manual removal, mulching, or targeted herbicide application.

Resources

References

  1. Riis, T., Kelly-Quinn, M., Aguiar, F. C., Manolaki, P., Bruno, D., Bejarano, M. D., ... & Dufour, S. (2020). Global overview of ecosystem services provided by riparian vegetation. BioScience, 70(6), 501-514. https://doi.org/10.1093/biosci/biaa041
  2. Griggs, F. T. (2009). California riparian habitat restoration handbook. California: River Partners. PDF
  3. Gornish, E. S., Lennox, M. S., Lewis, D., Tate, K. W., & Jackson, R. D. (2017). Comparing herbaceous plant communities in active and passive riparian restoration. Plos One, 12(4), e0176338. https://doi.org/10.1371/journal.pone.0176338
  4. Alpert, P., Griggs, F. T., & Peterson, D. R. (1999). Riparian forest restoration along large rivers: initial results from the Sacramento River Project. Restoration Ecology, 7(4), 360-368. https://doi.org/10.1046/j.1526-100X.1999.72030.x
  5. Moore, P. L., Holl, K. D., & Wood, D. M. (2011). Strategies for restoring native riparian understory plants along the Sacramento River: timing, shade, non-native control, and planting method. San Francisco Estuary and Watershed Science, 9(2). http://dx.doi.org/10.15447/sfews.2011v9iss2art1
  6. DiTomaso, J. M., & Healy, E. A. (2003). Aquatic and riparian weeds of the west (Vol. 3421). UCANR Publications.