Odd bark and a feral cat tale
Why eucalyptus bark sheds, Eve the one-eyed cat, and plant of the week
My recent posts about distinctive tree bark, while probably not setting pageview records, have interested at least one reader in learning more. And what more can a writer ask for, in this life? From California, Jim Santel writes:
“What can you tell me about eucalyptus bark, which is a delightful fixture of Stanford's lush campus? I'm especially interested in when and why the tree seems to molt its bark, resulting in an amusing hair-around-the-barbershop-chair effect.”
The first thing to know about eucalyptus trees in California is that they had an interesting way of getting there, as KQED describes. Australians arriving during the 1850s Gold Rush brought eucalyptus trees with them, having learned that much of the coastal landscape was covered with scrubby chaparral and wetlands that didn’t offer enough wood for heating and construction. The most common eucalyptus planted was Tasmanian blue gum (Eucalyptus globulus), which has the shedding bark that Jim notes.
Elsewhere in the bay area, UC Berkeley planted a dense stand of blue gum as a windbreak for their running track. That planting is emblematic of the story of eucalyptus in California at large, because the original trees spread to become possibly the biggest and thickest blue gum forest in the world. Opinions vary on California’s eucalyptus trees today, with some admiring them and some feeling they’ve outgrown themselves.
Like Berkeley, Stanford planted eucalyptus to create shade and windbreaks, including over 1000 blue gums along 1.6 miles of Gum Tree Lane, now known as Governor’s Avenue.
As for why the bark on blue gum peels, it turns out that scientists are still chewing on this question, as they are for the question of exactly why some leaves turn red in the fall, which Possum Notes took on last fall. It can be surprising to realize how much we still don’t know.
The primary reason for bark shedding is that for trees with thin outer bark, normal growth of the trunk causes the outermost layer to strip off gradually. But because some trees shed (sycamore, some eucalyptus species, juniper, shagbark hickory) and many others don’t (other eucalyptus trees, most oaks, maples, ashes), scientists wondered if there is some special evolutionary benefit to peeling bark. Perhaps if a tree’s bark flakes off, climbing vines have a harder time taking hold and competing for water and light, goes one hypothesis.
However, several studies have found no clear relationship between the amount of bark peeling and the amount of woody vines on the tree, with one study finding that peeling sycamore trees had even more vines than non-shedding maples. One interesting line of research looks at how eucalyptus bark type affects fire survival, but so far the most important trait seems to be bark thickness rather than flakiness.
It’s likely that one benefit of losing bark is protection from arthropod pests trying to eat sap, and maybe reducing the amount of flammable material on the tree to reduce the risk of dying in a wildfire. But it’s also possible that the benefits of peeling bark are just an added effect from shedding because of normal growth, and that evolution hasn’t pushed trees this way for any particular reason. If only trees could tell us why they act a certain way.
A former feral cat’s story
You came here for a newsletter mostly about the outdoors, so I don’t intend to talk often about my indoor pet and plants. But like many pet cats, our 9-month-old Eve was once living outdoors as a feral cat and originally found not far from our apartment. We adopted her from the Quincy Animal Shelter last month. I hadn't thought of myself as a cat person, but Eve quickly won me over—she's incredibly sweet and playful, and very vocal, making little chirping noises as she goes about her day.
But we noticed that her left eye seemed enlarged and that it bothered her. A visit to the vet and an ophthalmologist (turns out small animals have ophthalmologists, too) revealed that her left eye had very high pressure and in fact hadn't developed properly, meaning that she had lost vision in the eye and that it was giving her something like a constant headache as it presses against her optic nerve. And while her right eye was healthy and functional (her accuracy in catching toys is deadly), it had slightly elevated pressure already, too. The cause is likely a genetic form of glaucoma, given her young age and breed. Fortunately, we were able to start drops for her right eye that have decreased the pressure and will keep it healthy.
But due to the damage to her left eye, she was in a lot of discomfort (as you can imagine.) The vets recommended that she would have much improved quality of life if the eye were removed, and that young cats recover quickly from the procedure. And despite having a shoestring budget and relying largely on volunteers, Quincy Animal Shelter stepped in to help pay for Eve's veterinary bills, because they were just that invested in her success. The surgery yesterday went well, and Eve is recovering on cat-sized doses of painkillers, delivered with a little syringe into her cheek pouch.
I’m very grateful to QAS, first for taking in Eve in the first place, and then for adopting her to us with the stipulation that we’d keep her as a 100% indoor cat—as they do for all new cat owners. An indoor life is best for both the cat’s health and for protecting vulnerable wildlife. It’s not pleasant to think about how Eve would have fared as a feral cat, and one quickly going blind at that. I’m glad we have the chance now to give her a good quality of life inside. (I’m not letting this cat near any birds, because that right eye still works very well.) And then, I’m very grateful to QAS for being so invested in Eve’s well being that they helped pay for and coordinate her veterinary care even after adoption. If you’re inclined to join me in making a small donation to QAS in honor of Eve to support the good work they do, here’s a place to do so—thanks for any help.
Plant of the week: Eastern red cedar
I have a certain reverence for Eastern red cedar (Juniperus virginiana). It’s a juniper rather than a true cedar (i.e., the cedars of Lebanon.) Like blue gum eucalyptus, its bark sheds, in this case in long, narrow strips. The tree’s ability to sprout on the side of frequently salted roads, grow in soil dried into pottery shards, or push its way through dense undergrowth is a marvel. In my opinion, the tree looks its finest in a savannah opening of a forest, mixed in with other evergreens and deciduous trees and rising above tan-colored grass.
In Pilgrim at Tinker Creek, Annie Dillard recounts a moment when the pattern of sunlight changed and “the backyard cedar” became “charged and transfigured, each cell buzzing with flame.” This “tree with the lights in it” becomes the book’s touchstone for when the ordinary takes on a special cast of light and becomes numinous, sacred, majestic.
In a more mundane sense, red cedar often mixes in with deciduous forests and provides gold-green relief among bare branches and dead leaves, as in the oak-hickory woods in Missouri pictured above. Cedar groves are a place seemingly set apart in a forest, an area that looks designated for shelter and sustenance. Cedar waxwings, robins, and other birds seek out juniper “berries” (female seed cones) in winter.
Red cedar is native to this continent, but it tends to take up a disproportionate share of the ecosystem when not reined in by fire regimes. Fire suppression is the norm in most areas, so cedar can become a problem in grasslands and some forests. For that reason, I don’t mind using it for firewood in the rare instances I make a campfire. But I try not to handle the leaves, because they’re one of many things I’m allergic to.
The heartwood of cedar is beet-red, and the wood is fragrant. The smell of a cedar fire stirs up memories of all the campfires that have preceded it. The family grilling with cedar planks somewhere in the neighborhood probably didn’t mean to send me into a Proustian reverie over the scent of cedar smoke, but that’s what happened.
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Possum Notes is a weekly newsletter about wildlife and landscapes around where I live. It’s produced on occupied Massachusett and Wampanoag land.