The Daily Bucket is a regular feature of the Backyard Science group. It is a place to note of any observations you have made of the world around you. Rain, sun, wind...insects, birds, flowers...meteorites, rocks...seasonal changes...all are worthy additions to the bucket. Please let us know what is going on around you in a comment. Include, as close as is comfortable for you, where you are located. Each note is a record that we can refer to in the future as we try to understand the patterns that are quietly unwinding around us.
November 2013
San Juan Island,
Pacific Northwest
On a day trip over to San Juan Island to take care of some business at our county seat there, I went across the island to the west side to see one of the rarest habitats in western Washington, a Garry Oak woodland. The predominant feature of this ecosystem is the Garry Oak (Quercus garryana), the only kind of oak native to the Pacific Northwest.
It's important to realize that the San Juan Islands have never been wilderness. Ever since the ice sheet retreated 10,000 years ago at the end of the last Ice Age, and the islands emerged from the meltwater, people have lived here and worked the islands. But before "European" settlement of this area in the mid 1800s, there were extensive oak woodlands here, as elsewhere across the Garry Oak range (mostly northern California to southern British Columbia, on the coastal side of the Cascade Mountain Range). Today, small patches barely survive, although several organizations are actively restoring this habitat in places. What happened to the oak woodlands? And how can current threats be mitigated? I can provide a brief overview, with links to current research and restoration efforts.
The first thing you'll notice is that this oak is a deciduous tree, so when I hiked up there last week, the branches were bare and leaves littered the ground. It was a frosty morning.
In summer, the leaves are bright glossy green and substantial (this photo is from the Garry oak I planted in my backyard). The Garry oak is adapted to a dry environment and these thick leaves minimize water loss. The oaks also have a taproot and extensive lateral roots to take advantage of what little groundwater there is in our shallow soil, especially during our summer drought.
The next thing you'll note is that these trees are widely spaced, and sun reaches the ground, unlike most of the forests in the Northwest. This uphill patch of woodland/meadow is in English Camp, the northern section of San Juan Island National Historical Park, with Haro Strait visible toward the west.
More about the Oak Woodland below the nest of acorns...
Walking up the hill from the English Camp parking lot, the woods were typical of this area: lots of Douglas firs, some Hemlock, Redcedar, and Madrona. It's dark in there.
You can understand why these light, open, mostly cleared meadows were very attractive to the first settlers.
Oak Harbor, on Whidbey Island, was once a Garry Oak meadow, and chosen as the site for a town since it didn't require clearing first. Oak Harbor has a few oaks left, but there's a big difference between an oak tree and an oak ecosystem. The oak woodland/meadows throughout their range were mostly converted into fields and pastures.
In a healthy oak woodland, the meadow understory is composed of a multitude of forbs (herbaceous non-grass flowering plants) like chocolate lily, fawn lily, Calypso orchid, man root, small-flowered blue-eyed Mary, western buttercup, prairie star, spotted coralroot, common monkeyflower, small-flowered forget-me-not, field chickweed, white meconella, erect pygmyweed, common blue-cup, Nuttall’s quillwort, rosy owlclover, coast microseris, white-top aster, annual sandwort, brodeaias and great camas. This diversity promotes bird, mammal and insect populations.
Since I was here in November, I couldn't tell how many of these flowers live in this woodland. I've read there's a good number, but I can also see quite a lot of grass. Most grasses in the islands are invasive, planted by early farmers and spread by their grazing sheep. Grass tends to outcompete wildflowers.
One part of the meadow the grasses can't invade are the bedrock knolls. Much of this area is limestone, and where soil has not accumulated, only mosses and lichens proliferate.
A summer view of an oak woodland on Vancouver Island shows a healthy understory of forbs, mostly Camas in this view. Before Native Americans were displaced by settlers, they routinely burned oak woodlands to maintain the meadow understory, to cultivate Camas and promote deer/elk habitat. Camas roots were an important food source for the Coast Salish people. Families had specific traditional areas where the women
tilled, weeded and harvested camas to either eat immediately or store as flour for later.
Without periodic burning, fast-growing pioneer trees like Douglas firs, Red Alders and Madronas overtop the more slow-growing oaks, killing them with shade. I saw a patch of young firs at the edge of the woodland. If these are allowed to grow, in 20 years they will be taller than the oaks.
Old Douglas firs can survive burning because of their extremely thick bark. Here's an old one in the woodland. That's Mr O standing at the base, for scale. It is actually beneficial to have a few old trees interspersed with the oaks, protecting oak saplings from full direct sun.
Oaks have thick bark too, and withstand fire easily. If by some chance a Garry Oak does burn, it will resprout from the base.
Besides the end of periodic burning and the introduction of invasive grasses, there have been other consequences of settlers' activity. Four invasive insects - the winter moth, jumping gall wasp, oak leaf phylloxeran and gypsy moth - cause serious damage to oaks. Invasive European starlings aggressively displaced native Bluebirds from nesting sites, and the Bluebirds were gone by the 1960s. Along with the loss of native Steller's Jays and Flying Squirrels too, the oaks lost the benefit of "cachers", animals who would collect, disperse and bury acorns, increasing the chances of germination at a distance from the parent trees. Bluebirds have been re-introduced in the last decade. You can see a Bluebird house on the side of this oak.
Several public and private groups are working to restore these ecosystems. The National Park system has performed
controlled burns here at English Camp. The county
Land Bank is doing the same at other sites on San Juan and Orcas Islands. In Canada, the
Garry Oak Ecosystem Recovery Team has a number of programs in train. Restoration is not as simple as removing all the Douglas firs from oak woodland sites; after complete "canopy release" programs, usually invasive weeds take over, such as thistles, Scotch broom, English holly, Himalayan blackberry, and evergreen blackberry. Successful restoration requires gradual and partial tree removal, protective fencing of oak saplings against deer depredation, and other long term measures.
I enjoyed wandering among the old oaks on the hillside. Their gnarled and twisty branches are dramatically beautiful, especially bare like this, and so different from our straight limbed conifers. For some reason, we have no Garry Oak woodland meadows on Lopez Island, although there are a few shrubs on a bluff near the ferry dock.
...
The Daily Bucket is now open for your observations of nature from your part of the world. Native survivors? Invasives threatening? Signs of winter? Please describe in the comments below.
"Green Diary Rescue" is Back!
"Green Diary Rescue" will be posted every
Saturday at 1:00 pm Pacific Time on the Daily Kos front page. Be sure to recommend and comment in the diary.