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Native Trees and Riparian Habitat

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    Interpretive Panel #5 – Riparian Corridors and Riparian Trees

    Spanish Version Located Here

    A riparian corridor is defined as a community of plants growing together alongside a creek, stream or river.  A healthy riparian corridor is often quite dense, with all sizes of plants contributing to the corridor, including grasses, wildflowers, shrubs, vines, and trees.

    Riparian corridor C2012 Jean Pawek Cal Photos Creative Commons Copyright

     

     

     

     

     

     

     

     

    Riparian corridors often contain dense stands of trees, shrubs, vines and understory plants. Photo credit: © 2012 Jean Pawek (CC BY 3.0)

    This abundance of vegetation provides fantastic wildlife habitat, and riparian corridors support diverse and abundant animal communities. Tall trees allow birds to nest up high away from predators, dense understory vegetation below provides places for wildlife to hide in and travel along, and the seeds and nuts produced by riparian plants form the base of the entire food chain.  More species of birds nest in riparian forests than any other plant community and over 125 species of mammals live in riparian corridors. 

    Riparian corridors used to exist along all of California’s waterways.  Larger rivers (such as the Sacramento River) contained dense riparian forests that were up to several miles wide in places, while smaller creeks (like the tributaries of Horse Creek here in Centennial Park) may have had corridors that were only a few dozen feet wide. All provided important wildlife habitat. 

    The riotous vegetative growth that defines a healthy riparian corridor is possible because of the abundant water and rich soil found there.  Flood events occurring over the millennia have deposited layers of nutrients and organic matter along the banks of waterways.  Riparian soils are usually a rich loam, with the perfect balance of sand, clay and organic matter to maximize plant growth.  

    Cottonwood C2013 Jean Pawek Cal Photo Creative Commons Copyright

     

     

     

     

     

     

     

     

    Cottonwoods are common trees in riparian corridors and are always found growing near water. Photo credit: © 2013 Jean Pawek (CC BY 3.0)

    These rich soils have not gone unnoticed, and as California agriculture has intensified over the last 150 years, crop plants have gradually replaced native plants along most of California’s creeks and rivers.  Most riparian forests are now much narrower, degraded, and in some cases completely non-existent.  Only 5% of California’s original riparian forest acreage remains today and wildlife populations that depend upon these corridors have been greatly reduced.

    In recent decades, the many benefits that riparian corridors provide has become better known, understood, and appreciated.  In addition to high-quality wildlife habitat, riparian vegetation also protects water quality by filtering sediment and pollutants out of overland runoff, reduces stream bank erosion, and provides a beautiful setting for recreational opportunities.  Restoration projects sponsored by the State of California, local public agencies, and a wide variety of non-profits are now restoring riparian corridors throughout California.

     

     Valley oak leaves and acorns C2008 Keir Morse Cal Photos Creative Commons Copyright

     

     

     

     

     

     

     

     

     

    Valley oak acorns provide food for many different species of wildlife. Photo credit: © 2008 Keir Morse  (CC BY-NC-SA 3.0)

    With funding from the California Natural Resources Agency and the assistance of many community volunteers, the City of Vacaville and Solano Resource Conservation District planted

    over 575 riparian trees (as well as many shrubs, vines and understory plants, see Interpretive Panels #4 and #10) along two tributaries of Horse Creek.  A number of different tree species native to riparian corridors in California’s Central Valley were used, including:

    • Arroyo willow (Salix lasiolepis)
    • Black willow (Salix gooddingii)
    • Box elder (Acer negundo)
    • Cottonwood (Populus fremontii)
    • California black walnut (Juglans californica)*
    • California buckeye (Aesculus californica)*
    • California sycamore (Platanus racemosa)*
    • Interior live oak (Quercus wislizenii)*
    • Oregon ash (Fraxinus latifolia)
    • Red willow (Salix laevigata)
    • Valley oak (Quercus lobata)*

     

    Some of these trees (three species of willows as well as cottonwood, box elder and Oregon ash) normally grow near creek edges and require lots of water to thrive.  Others (CA black walnut, CA buckeye, CA sycamore, interior live oak and valley oak) grow further from the water and are therefore much more drought tolerant.  They are marked with an asterisk (*) above.  Here in Vacaville, these naturally drought-tolerant trees make great additions to home landscaping.  Not only do they provide shade from our hot summer sun, they also provide local wildlife with food and other important resources. 

     

    California buckeye C2009 Barry Breckling Cal Photos Creative Commons Copyright

     

     

     

     

     

     

     

     

     

     

     

     

    The California buckeye is actually quite drought tolerant and is a lovely addition to residential landscapes.  Photo credit: © 2009 Barry Breckling (CC BY-NC-SA 3.0)

     

    This information has been provided by the City of Vacaville in partnership with the Solano Resource Conservation District.  It was last updated on December 31, 2019.