Article provided by Rose Creek Watershed Co-Coordinator Caitlyn Toropova

As anyone who has driven along SR-52 between I-5 and I-805 knows, there are some steep canyon slopes in our watershed. You also probably know that many of

Hottentot Fig Iceplant  (Caprobrotus edulis)

them are covered in iceplant [in our watershed, mostly Hottentot Fig (Caprobrotus edulis)] or manicured with palm trees from far off tropical lands. These slopes were landscaped like this over forty years ago, back when it was thought that iceplant controls erosion, spreads easily, reduces fire risk and requires little water. It turns out that only two out of four of these beliefs are true. Iceplant does spread easily, and it does require less water than some other plants. 

 

However, it turns out that iceplant is bad news for creeks and canyons. University of California's Division of Agriculture and Natural Resources reports that iceplant's

A nasty landslide down a canyon slope covered in non-native iceplant.  Photo from www.cnps.org.

near impenetrable shallow rooted mats and underlying thatch can become a fire hazard. Additionally, iceplant has such a shallow root system that it does not drain when it is overwatered. This results in a slick mat that can erode the entire top layer of soil and create a landslide down the slope [sources: Las Palitias Nursery (Escondido), California Native Plant Society, and Surfrider Foundation San Diego Chapter]. Iceplant is often watered via antiquated sprinkler systems that spray anything and everything around it, resulting in much higher water use than needed. Fertilizers used on the iceplant can result in negative downstream effects for nearby creeks, and it crowds out native plants which provide critical habitat for local wildlife.

What are we doing about it? Recommendation 2.2.2 in the Rose Creek Watershed Opportunities Assessment suggests controlling invasive non-native species such as iceplant. In 2012, an outreach effort to the property owners along the canyon slopes was initiated as part of the Rose Creek Watershed Invasive Plant Control Project. At the same time, multiple incentive programs began appearing from the City, County and State as drought conditions worsened. It soon became obvious that converting iceplant-covered slopes to natives would benefit both the watershed and the region by reducing erosion, increasing native habitat, and conserving irrigation.

This effort will require the cooperation and dedication of the property owner or Homeowner Association and funds to remove the iceplant, update the watering system, and plant and mulch the new plants. Ongoing education and involvement of the community is also key. With the help of partners with pre-existing outreach programs such as Think Blue San Diego and the California Native Plant Society, we are already discussing a partnership with a potential property owner who will review their native plant options as they embark on a landscape retrofit.

What are our next steps? We envision this effort to begin locally with several "success sites" and then for it to scale up to San Diego County and Southern California. We would expect each site to take at least two years to reach full maturity, at which point we would begin to see many benefits including reduced watering, increased habitat, improved erosion control, and better water quality in Rose and San Clemente creeks. Contact Caitlyn Toropova for more information on this effort.

Convener: San Diego EarthWorks

San Diego EarthWorks convened the Rose Creek Watershed Alliance in 2004 as an informal organization of stakeholders to help plan the future of the 23,000-acre Rose Creek Watershed. They developed a planning document to encourage watershed improvements called The Rose Creek Watershed Opportunities Assessment. The Assessment includes recommendations to improve the watershed's biological, cultural and recreational attributes and was accepted by the San Diego City Council in 2008.