Archive for the ‘other’ Category

Survivor trees

10 August 2015

I’ve been poking around Oakland’s edges lately. In southernmost East Oakland there’s not a lot of geologic history, but there are some big old trees, survivors of optimistic times, plus nice views of the hills and sky.

This is one of our largest and oldest jacarandas, on 92nd Avenue. (There’s a comparable one on Pippin Street.)

jacaranda

And here’s an even more exotic visitor, an Araucaria from the southern hemisphere (a monkey-puzzle tree, I think) in Sobrante Park.

monkeypuzzle

On 105th Avenue, next to what appear to have been Oakland’s last commercial greenhouses, we have a big old lot where there used to be something but now there’s just a large generic tree. What has it survived?

lone-tree-105th

The ground here is mapped as Bay mud, just past the seaward edge of the alluvial fan of San Leandro Creek. If the soil is still clean, it should be rich stuff.

Down at the end of 105th Avenue, hard by San Leandro Creek, is a cluster of venerable black walnuts.

blackwalnuts

Unlike the previous trees, these may well be natives. At least the species is right and the riparian (streamside) habitat is correct.

There are surely people in Oakland who remember the stories of these trees.

But I really wanted to talk about another old survivor tree, up in the hills on the south side of Horseshoe Canyon. In fact “Old Survivor” is its name. This last week I had the opportunity to visit it with a small group of people. It’s older than any human memory in these parts.

old-redwood-sign

The group tended to refer to the tree as “the Grandfather Tree.” I thought “Grandmother” was a name just as good. But the DAR, in chiseling “Old Survivor” on this monument by Campus Drive at Carl Munck Elementary School, established priority. The age is subject to revision, though. The 1981 monument put the tree’s age at 425 years, but there’s no birth certificate for this baby. The tree was cored in the late 1960s, and its age at that time was estimated as 415–420 years. Let’s make 1550 its germinal year. So today it would be 465 years old. Here it is.

old-redwood-up

The Old Survivor is about 100 feet tall and has presence, especially when you think of it as the last old-growth redwood left in its East Bay stronghold. However, the loggers let it be because it was, and is, a scraggly, marginal specimen. Part of its uphill side is bare, fire-scarred wood. It’s flanked by two nuisance trunks that were less than marketable size in the 1850s redwood rush. The slope it sits on is more of a cliff, and had it been toppled it would have shattered.

The Old Survivor is rooted on Leona “rhyolite” rather than the moist mudstone of the Redwood Formation or Oakland Conglomerate that redwood prefers. But it’s fitting that Oakland’s oldest tree grows from Oakland’s oldest rock.

old-redwood-base

While the tree consists of a triple trunk, the central trunk stands above its siblings pretty well, if I can judge from the photos on oaklandwiki. I took a photo of its crown from the west side.

old-redwood-top

Old Survivor isn’t pretty, and it’s very hard to visit, but it’s still precious: the last bit of our forest primeval.

Trees and serpentine

29 March 2015

There’s a stretch of Castle Drive, up in the Piedmont Pines neighborhood, lined with huge trees. On the Walk Oakland map, it’s even labeled “Colonnade of Eucalyptus.”

CastleDrTrees

These give me mixed feelings, as tree removal projects have aroused lately elsewhere in Oakland.

First, there’s the experience the trees provide. For one thing, you basically can’t walk here, so the colonnade is not a realistic attraction for walkers. Its main effect is a momentary diversion for drivers, who really don’t need one at this location.

Second, there’s the effect on the surroundings. As you climb up in this valley, the trees emerge as a very tall fence that blocks the view of the hills and the city and the bay.

Third, there’s the geologic setting. This part of the roadway runs along a very steep 40-degree slope through pure serpentinite, visible in the small landslide scar on the right side of the photo. Serpentine rock is poor footing for these massive trees. The trees may seem like they’re buttressing the roadway, but when they inevitably tip over in a storm or earthquake, they’ll uproot it instead, forcing the locals to drive up and down Ascot Drive for many months.

But how about that rock? Here’s a hunk of it that spilled across the road.

castleserpfoot

And here’s a hand specimen. I love this stone, but roadbuilders don’t.

castleserphand

It’s not my problem, since I don’t live there, but I think the best thing to do is to turn this colonnade into a line of ground-level stumps. The root systems would bolster the soil for another decade or so, giving the city time to plan and execute a properly engineered roadway. And bollards set in the stumps would preserve the trees’ most useful current function of keeping cars out of the canyon.

Trees are supposed to be wonderful stockpiles of carbon, sequestering it from the atmosphere. For me, that argument shouldn’t apply to individual trees or even individual groves of trees. What do we do, in the long run, with the carbon in trees—pile the trunks in pyramids? Carbon is best stored in the soil, where it provides excellent tilth and maintains a thriving ecosystem that resists fire and drought. It’s like circulating money in an economy: do you hoard it in vaults or spread it around among people ready to use it as a medium of exchange? Humans have spent thousands of years degrading the world’s soils, and I’d rather we begin to restore them.


Follow

Get every new post delivered to your Inbox.

Join 9,267 other followers