|Summer-dry brown in October. That's SoCal.|
Something for us ecologists to consider when we are restoring land to natural conditions. How do we convert abandoned agricultural fields, mining pits, eroded bluffs, dissolving roads, buried or channelized creeks to diverse, functioning, sustainable natural systems? In the future climate, are these areas best suited as forests, grasslands, chaparral or ephemeral streams? With climate change, there's no going back so what is the path forward?
|Riparian restoration in the floodplain of the Santa Ana River in southern California. The mulefat cuttings have multiple stems and are over six feet high in just 10 months. Sunshine.|
We spent quite a bit of time discussing these issues at the 2013 California Invasive Plant Council symposium in SoCal. My initial conclusions: expect change, design with flexibility, watch and adjust. And, we have to change our strategies and priorities. It won't be easy. We'll need to be humble and keep adjusting.
On a field trip, we visited restoration sites along the Santa Ana River from foothills to valley floor. With 50 tributaries over 3000 square miles, the Santa Ana River watershed is the largest in southern California. As it flows from the San Bernardino Mountains in the east to the Pacific Ocean in the west, it crosses San Bernardino, Riverside, Orange and Los Angeles Counties, home to 4.5 million people. I've always been a little intimidated by the busy cities of southern California, but following the river downstream gave me a greater appreciation for the beautiful natural areas holding strong in this busy area and the people nudging them along to healthy ecosystems. If I was a bird tumbling down this olive network, I could find a place to eat and rest and breed.
At Hidden Valley Wildlife Area near Riverside, the Santa Ana Riverside Association is removing 500 acres of nonnative invasive species and restoring the area to native riparian (=streamside) habitat. The primary invasive plant target is giant reed, basically a giant grass that grows in dense continuous patches and outcompetes the complex arrangement of native SoCal streamside plants.
After cutting and chipping the giant reed stands, and returning again and again for a few years to remove the expected resprouts, the Santa Ana Watershed Association staff and contractors jumpstarted the recovery of the natural stream forest by planting cuttings of native red willow, Fremont cottonwood and mulefat. The cuttings are watered for a few years by a temporary drip irrigation system.
The star performer in the restoration effort is mulefat which quickly establishes roots underground and sprouts multiple stems aboveground that shoot for the frequently present California sun. Not every plant will survive, especially once the irrigation is removed in a few years, but by producing initial vegetative cover, the mulefat plants create niches for native seeds and rhizomes to lodge into the recently cleared soil and a more hospitable micro-climate for them to grow.
Meanwhile, the clever and adaptable coyote can't seem to wait for the riparian forest to get on its feet. Coyotes have figured out that the black plastic tubes twining across this nascent restoration site are full of delicious water. Water that comes spurting out when you bite the irrigation tubes.
Oh dear, competition between wildlife and young native plants over fresh water, a limited resource in this semi-arid environment.
|Coyote waterbowl. Sometimes, the wildlife just can't wait for you to get that natural system functioning.|
The riparian plants will develop deep roots that tap into underground water resources and develop waving green canopy above ground in a few years so that they no longer require irrigation or temporary human intervention. The drip irrigation system will be moved to another young riparian forest.
|At the Dipper Ranch, a nearly grown coyote takes advantage of an abandoned spring box for summer water.|
Thanks to the Trickster for reminding us to stay on our toes.
giant reed, Arundo donax
red willow, Salix laevigata
Fremont cottonwood, Populus fremontii
blue elderberry, Sambucus nigra spp. caerulea
mulefat, Baccharis salicifolia
California sycamore, Platanus racemosa
Hairy-leaved sunflower, Helianthus annuus
coyote, aka the trickster, Canis latrans