California Native Plant Society
in collaboration with East Bay Municipal Utility District
September 26, 2019
We had our first rain of the season last week with half an inch up at Skyline. Let's hope its a sign of more early rains to make up for last year's late November start. Congrats to Carla for making the closest guess; big prize on the way.
Meanwhile, we're hoping to soon wrap up our Scattergrass work, which along with Spurge, continues to be our main focus. With the passing of the equinox, we are shifting our Wednesday afternoon time to 3 pm, and will still keep our Sunday morning time of 9:30. Please let me know if you can make it.
Our Skyline Gardens effort is now three years old. So, for a "big picture" look at our efforts so far, I will insert below an article I have just written for the October Bay Leaf (East Bay CNPS's monthly newsletter). This is a summary (with graphics and pictures) that touches on some of what we've done and learned, focused on our efforts to restore the High Ridge Meadows.
"Skyline Gardens: Ecological Restoration of the High Ridge Meadows
Ecological restoration is the process of assisting the recovery of an ecosystem. The Skyline Gardens Alliance, a project of East Bay CNPS, has for three years had, as one focus, restoring "High Ridge Meadows" of the steep, volcanic ridge area between Tilden and Sibley Regional Parks. Skyline Gardens is East Bay MUD Watershed land, traversed north-south by the East Bay Skyline Trail. Under permit from EBMUD, which allows us to go off trail, we have been carrying out a botanical survey and ecological restoration in the roughly 250 acres of Watershed between Tilden Steam Trains and Hwy 24. Our effort is now 3 years - and thousands of on-site hours - old and we have learned a lot.
As background, this whole ridge sits atop layers of volcanic rock known as the Moraga Volcanics, the name for the series of eruptions here roughly 10 million years ago. These volcanic strata have now been tipped to nearly vertical. Sibley’s Round Top, Grizzly Peak proper, and Tilden’s Vollmer Peak are the three of the best-known high points along the ridge.
Because volcanic or basaltic rock is very hard and weather resistant, these volcanic ridges are the tallest and steepest parts of the Bay Hills, with an average elevation of 1,600 feet. We refer to this greater volcanic area, which extends from Inspiration Point south to the new McCosker annex of Sibley Park, as the "High Ridge Volcanic Area". (Graphic thanks to Joe McBride).
The ridge area separates the cool bayside flatlands from the hot interior – it is where the fog meets the heat. The ridge area receives the highest average annual rainfall in the entire East Bay, averaging 34 inches, with up to another 8 inches of extra fog drip each year. Volcanic soil is very fertile and has unique properties; volcanic areas are laced with springs and seeps. Because of the rockiness and steepness, this area has historically been only lightly grazed commercially. The result is a veritable Noah’s Ark of native plants. Skyline Gardens is the most botanically diverse area of its size in the entire East Bay. Here, we have verified 282 native species to date, nearly 70 of which are on the EBCNPS list of rare and unusual plants.
Along the rocky ridge spines, we have discovered special areas that have really won our hearts. We call them the High Ridge Meadows. They are very rocky, the soil is very thin, and they tend to be hot and sunny places. They contain spectacular, sometimes nearly intact, remnants of “what must have once been.” They are true meadows, containing very few woody plants. They contain some of the best and most diverse populations of native grasses that I have ever seen in the East Bay: Idaho Fescue, June Grass, Squirreltail Grass, Purple Needlegrass, California Brome, California Melic, Bent Grass, and even Pine Bluegrass. They also contain a rich assortment of native perennials and bulbs: Mule’s Ears, Checker Bloom, Yellow Biscuit Root, Cobweb Thistle, Star Lily, Ithuriel’s Spear, Coyote Mint, Soap Root, and many others. These wild ones grow not just as relicts, but often in great abundance, literally by the thousands.
Here’s a photo of one meadow area that is still relatively intact:
In this early April photo, we see Mule’s Ears (big yellow), Blue Dicks (small blue), Yellow Biscuit Root (small yellow), Indian Paintbrush (red), Poppies, and many native grasses and forbs – all mingling among the fabulous, lichen-covered, volcanic rocks. Up here, it feels like the High Sierra at peak bloom, but it's right here at home.
But truth to tell, these High Ridge Meadows are also badly degraded and threatened by invasive annuals, such as Italian Thistle, Poison Hemlock, Rose Clover, Mustard, Wild Oats, Erodium, and a whole witches brew of some 60 other exotic species. The native annuals grow relatively sparsely in these meadow areas, having been almost completely choked out by the exotics.
These High Ridge Meadows are some of the “last of the best” places we have in the East Bay. Their special magic has called forth a huge effort on our part, literally thousands of hours, to assist them on a path to recovery. Working from the base of a rich backbone of native perennials, our basic strategy is to exhaust the seed bank of the invasive annuals. Our motto: “Remove the Exotics.” Most of these invasives are annuals and their seeds are actually quite short-lived in the soil. They quite straightforward to eradicate in a 3-year time frame – IF they are not allowed to go to seed. That said, it is tons of glorious and fulfilling work and requires diligence and exacting follow-up to make sure the invasives do sneak through and reseed.
The restoration sequence can be outlined in this graphic:
Of special note is our pioneering work in the use of vinegar spray (5% acetic acid) to kill young invasive seedlings. We use backpack, professional grade (Solo 4 gallon) sprayers. Vinegar is quite effective, especially on the broadleaf seedlings (dicots), when done within two months of the first rains that bring up new growth. If we spray this early, the native perennials and bulbs are still dormant, so we can spray right the tops of them. We think this is very clever. Horticultural grades of Vinegar are available at 20 to 30% acetic acid, but expensive. We find that a dilution down to 5% acetic acid is very effective (photos below). (By the way, ordinary household distilled white vinegar is already diluted to 5% acetic acid; and, the generic is much cheaper to buy - $2 a gallon at COSTCO, for example).
Vinegar is a natural product that is already present in almost all living tissue. It is fermented from fruit or grain. Vinegar is a simple molecule that breaks down quickly and naturally to water and CO2. It does not persist in or acidify the soil. Vinegar is a ‘contact spray’ that burns the foliage of plants, but unlike systemic weed killers such as Roundup (glyphosate), vinegar is not taken into the stems and roots. Vinegar may require follow up sprays or hand weeding, especially on large-seeded grasses like Wild Oats. If you want to test this at home, put a cupful of household vinegar in a hand-spray bottle and try it yourself.
Here's some samples of 5% vinegar’s effectiveness as an herbicide at Skyline Gardens:
The photo above is three days after 5% vinegar was sprayed (left side) on a raffish section of High Ridge Meadow that was heavily degraded with exotic annuals.
Below is a close up of the effect on Italian Thistles:
The dead one (left) is two days since spray. (Photo thanks to Cynthia). Notice how the root branches are all gone. The live one (right) was unearthed a minute before the photo. For some reason, vinegar is particularly deadly on Italian Thistle, which is an annual, and even kills the taproot in the rosette stage (up until early March, before they start to bolt).
As to the overall results of removing the invasives, below is a High Ridge Meadow terrace, looking southwest, after one year of mowing, spraying and hand weeding (Sibley off in the distance):
All plants in this early April photo are natives: besides the bloomers (Blue Dicks, Poppies, and the Yellow Biscuit Root), there are several species of native grasses (Purple Needlegrass, California Melic, and June Grass), Soap Root, Golden Aster, and Buckwheat. Gone is the blanket of thistles, Rose Clover, and Erodium, that had covered and choked the natives growing underneath.
In the third year, or once the invasive seed bank is nearly extinguished, we can then sow with a mix of locally gathered native annuals. After that, having put into place the essential elements of ecosystem recovery, our job is to keep the focus on the occasional weeds and let the natives sort themselves out as they best see fit.
Here's another example, looking east to Mount Diablo, right along the edge of the Skyline trail:
Three years ago, this trail edge was a menacing thicket of Italian Thistles. Underneath were a few poppies and Popcorn Flowers. With the thistles gone, the natives have come roaring back. (Photo thanks to Meredith).
Our spirits soar as we nurture this beautiful land back to wholeness."