15 Years of River Partners’ Science: Past, Present, and New Directions
By Andrew Rayburn, Restoration Ecologist,
Since our inception, River Partners has earned a strong reputation for designing and implementing science-based restoration projects. From the beginning, we adopted sound horticultural techniques, with native woody species planted in rows and maintained using agriculture practices like irrigation and weed control. We also considered factors that remain important to riparian restoration planning, such as soil characteristics and land-use history.
Figure 1. An experimental native grass plot at the Ord Bend Project in Glenn County.
At the same time, we were becoming curious about the potential to include native understory species in addition to overstory trees and shrubs. Our hypothesis was that native understory species could further enhance wildlife habitat, as well as serve as a barrier to weed invasion in years after restoration. On River Partners’ first project at Ord Bend in Glenn County, a cover crop was planted in year 1 between rows of native woody species. The following year, 4 native grass species were planted to replace the cover crop, and 10 native grass species were added into smaller experimental plots to examine species responses to the 5 different soil types spanning the 50-acre site (Fig. 1). A robust annual monitoring effort demonstrated gradual increases in native grass cover, and soil types strongly affected which species became dominant through time. At a 777-acre site on the San Joaquin River National Wildlife Refuge, we experimented with native grasses and broadleaf species for understory restoration, including mugwort, gumplant, and creeping wildrye. River Partners staff collected native seed for propagation and tested seed viability and germination requirements. Stephen Sheppard, our Director of Operations, worked hard to implement these practices (Fig. 2), and he also evaluated additional understory species for use by River Partners (a process that continues to this day).
Figure 2. For many years, River Partners employees have tested the potential of various native understory species for use in restoration projects.
Through the years, we have used our science-based approach to tackle a wide array of challenges and to improve success on riparian restoration projects on major rivers throughout California. Our focus has expanded to include planting designs to benefit various wildlife species, such as the creation of habitat mosaics to maximize the niches exploitable by breeding songbirds. Early riparian restoration efforts targeting species such as the yellow-billed cuckoo generally had low plant species diversity and rather uniform vegetation structure. Discussions with wildlife conservationists led us to increase the number of woody shrubs and other non-tree species in order to create variation in habitat structure that would benefit suites of songbirds, rather than focusing exclusively on single species. Long-term monitoring of wildlife by staff from River Partners and Point Blue Conservation Science (formerly PRBO) has verified the success of these designs. Over an eight-year period at the Beehive Bend project in Glenn County, Point Blue staff found that avian species richness in restored forests increased to approximately the same levels as found in neighboring remnant riparian forests (Fig. 3). River Partners has also created planting designs to aid in conservation of endangered mammals. For example, restoration projects at the San Joaquin National Wildlife Refuge have included carefully designed habitat features for the endangered riparian brush rabbit, which requires dense shrub cover and high-ground refugia during flood events (Fig. 4). A similar approach has been taken in the initial stages of restoration at our large-scale Dos Rios Ranch project at the confluence of the Tuolumne and San Joaquin rivers (Fig. 5)
Figure 3. Our habitat mosaic designs benefit a suite of native birds, including the spotted towhee (Pipilo maculatus) (Photo courtesy of Michael Rogner)
Figure 4. Vegetated bunny mound (a.k.a., high-water refugia) at the San Joaquin River National Wildlife Refuge provide places to which wildlife can retreat during floods.
Beginning with the O’Connor Lakes project in 2004, River Partners also began to contract with consulting firms to perform hydraulic modeling in support of our permit applications to the Central Valley Flood Protection Board. These permits, which are required in advance of planting native woody vegetation in floodways, are only issued after applicants can demonstrate that planned restoration activities will not increase flood risk to surrounding areas. Since then, most of our projects have had some level of hydraulic modeling as part of planning and design, guiding River Partners scientists to adopt a broader, watershed perspective and to consider ways to achieve flood neutrality while maximizing habitat value and other benefits.
Over the years, we have also delivered scientific results and “lessons learned” to an increasingly broad audience across California. Our projects have been presented at a wide variety of professional workshops and conferences, such as those hosted by the California Invasive Species Council (Cal-IPC) and the California Society for Ecological Restoration (SERCAL). In addition, we produced the widely read California Riparian Restoration handbook in 2009, a work that continues to be downloaded frequently from our website. River Partners scientists have also been co-authors on peer-reviewed publications in scientific journals, as well as producing numerous outreach articles in journals and newsletters of SERCAL, the California Native Plant Society, and the California Native Grassland Association.
5Figure 5. A recently constructed bunny mound at the Dos Rios Ranch restoration project in Stanislaus County.
On our 15th anniversary, we are proud that River Partners has established a reputation for science-based habitat restoration for the benefit of people and the environment. We are continuing to seek ways to expand our internal body of scientific knowledge that underscores our successful restoration projects. We have expanded the number and scope of our field experiments with tests of additional native species, new restoration and monitoring methods, and techniques designed to reduce restoration costs. We have also expanded our efforts to translate our projects and results to a broad audience of stakeholders spanning state and federal agencies, private-sector consultants, non-profits, and restoration practitioners. Both our internal and external scientific efforts are being bolstered through new and continuing partnerships with academic researchers, non-profit and agency scientists, and private-sector consultants.
At the same time, we are working on translating and marketing our science-based restoration practices to effect changes within the framework of state and federal agencies as well as the broader policy arena. Questions we are considering include: How can we apply our experience to reduce or remove permitting and policy hurdles that affect not only River Partners’ project success, but also the larger conservation landscape of California? How do the results of our long-term project monitoring efforts inform ongoing debates about vegetated levees and planting woody vegetation in floodways? In addition, how can we leverage our experience with funding acquisition and partnership building to support regional and state-wide coalitions working to advance multi-benefit projects along California’s major rivers?
For 15 years, we have used science-based restoration approaches to become an industry leader in the field. Now the challenge is to continue to accomplish our core mission by improving our restoration practices, while capitalizing on our expertise to engage broader issues relating to wildlife conservation, habitat design, and floodway policy.
The above article originally appeared in the May 2014 issue of the River Partners Journal.