Why Healthy Oaks Drop Branches

Heard it about 11 p.m.: Slow cracking and then a whoosh and thump. This is the third time in 14 years so I know what it is, and outdoors with a flashlight--stepping very carefully in case any copperheads are out lounging on the gravel like before--see that one of the twin oaks, tall and very old but thriving, has dropped a huge live branch, blocking the lane but causing no damage. I text the handymen and they chainsaw it up the next morning.

Before they arrived I had a good look at it and wondered why well-leafed oak branches drop and found an excellent online article by Heather Hacking (a fine name for a reporter interested in botany) who interviewed arborist Scot Wineland:

"Trees draw up a tremendous amount of water during the day and release the moisture through their leaves. The process is known as evapotranspiration.

If you tied a plastic bag around a potted plant, the bag would become cloudy as moisture is released to the air. If the tree hasn't had a chance to shed some of that moisture, the "phenomenal weight" of the water can bust a limb.

Sometimes a tree will have an ever-so-slight defect, or a crack. Perhaps woodpeckers or squirrels damaged the limb in a way that leads to a larger crack over time and later decay.

When the limb gets too heavy with water, that crack can lead to a break. There can literally be buckets of water that flows from where the limb breaks, the arborist said."

See the entire article here. It's from the Chico, California Enterprise-Record. Maples and other trees have limb drop, too.

I didn't see any water in the morning, nor any black ants at the core of the fallen branch, but that doesn't mean they weren't there, because my eye is untrained. I am relieved the 25-foot branch didn't fall on anyone or anything.

Peace I Ask of Thee

After the forceful Christmastime flood, LaBarque Creek has radically changed its course through the property, eroding its banks, and moving tons of rocks pulverized into dunes of pure white sand. I will need to visit at different times of day in order to obtain just the single photo image that'll show you just how striking are the huge new creekside "beaches" where there were none, new "islands" made of broken fossil rocks, and full-grown trees uprooted and fallen, creating new directions and chutes for the creek water, and also new depths, and therefore new colors--because for the last several years the LaBarque, as it passes through the property, has been shallow everywhere, lacking a swimming hole (last swum in 2008) or worthwhile fishing hole.

What you see here is a tree growing sidewise now, horizontally, a few feet above the water, out of a bank that has just about completely eroded beneath it, and the newly green creek water, deeper now than when it used to run gold. For some reason it looked like a Japanese print to me.

Early spring, right now, is the best time of the year, freshest (like a new book), full of light (with the trees yet leafless) and most heartening and promising.

Heartwood

Somebody sawed down a red cedar. Inside is a heart red and blooming just like ours. A botany teacher once told us that plant cells and animal cells are alike, except plant cells have walls, and animal cells don't. What does that mean, we asked. "It indicates a common origin," he said.

The Beavers are Back

At dawn hearing shotguns too close to the property, I later suited up to look for trespassers, and instead found enchantment: a new beaver dam across LaBarque Creek. (Video: 2 minutes 20 seconds.)


Beavers dive and swim beautifully. The dam creates a pond deep enough to discourage predators and hides an underwater entrance to their lodge, where they sleep just above the rushing water. At right is a photo of what they did to a tree. If a tree trunk is too big for their purposes, they gnaw off and use the branches. Beavers eat the tree bark and the cambium (the soft tissue growing between bark and wood), and adults are 40 pounds or more, and sleek.

Drought's First Casualty

I heard "CRAACK!" and turned just in time to see this fully-leafed branch from the huge twin oak peel off and land, completely blocking our only access road. Thank God I wasn't under there and my car was garaged. My neighbor and I were now trapped so I phoned the handymen at once. They said, first thing in the morning. With time to inspect it I tried to find out what had gone wrong with a branch that looked healthy.

What looks like interior rot is the tree's heartwood, and in any tree it's dead already, having done its job. As you know, a tree feeds itself through the wood just beneath the bark, and its concentric rings are what hold it up. It's like a hollow metal pole; its strength doesn't depend on its core. I didn't see real rot. And a sick or bug-infested branch wouldn't have such healthy greenery.

It was, however, a horizontal branch on a very old tree, richly weighted with other leafy branches, after two consecutive years of severe drought. In June we didn't get a full inch of rain here (the city got a bit more than we did). Our towns cancelled Independence Day fireworks for the first time ever because of the fire hazard, and I hope the kids shooting off fireworks for fun aren't doing it anywhere near our dry-as-dust woods and fields.

Where the branch peeled away

Next morning the handymen chainsawed the branch and also amputated the branch from the redbud across the lane that broke beneath the weight of the oak branch. The twin oaks must be among the oldest trees on the property; they are 80 feet high at least and a glorious sight as you drive up toward the house. Branches do fall from them sometimes, but usually only dead ones. Hope not to see any more like this.