The autumn of 2018 was a mast year for acorns in the Sierra Nevada foothills. The valley oaks, Quecus lobata, on my property, in Columbia California, produced prodigious quantities of acorns. I had noticed some size variation between the valley oaks located in different parts of the property, and did not think much of it. When I was at the massive house fly invasion job, I noticed that the acorns there were gigantic, far bigger than those at my house.
These giant acorns were coming off large valley oaks that grew along a year-round stream. The stream, on a cattle ranch near Chinese Camp, was fed by a spring, and it even had minnows in it, California roach, a fish that can survive in intermittent streams. A couple of the valley oaks on my property grow along a season creek, which had not had water since spring.
It appears that acorn size may be related, at least in part, to the water available to the tree when the acorns are growing.
These photos show the remarkable size variation in valley oak acorns.
Valley Oak A is from the Chinese Camp trees, fed by a year-round creek.
Valley Oak B is from across the street from property, from a huge and old valley oak growing alongside a season creek. The creek had water in the winter and dried up mid-spring.
Valley Oak C is from my property, from a somewhat smaller valley oak, and has larger acorns than the largest of my oaks. It is more downhill from “B”.
Valley Oak D is from across the street from my house, nowhere near a creek, uphill from the other oaks. IT appears to be the most water starved of the four oaks compared.
At about 10:45 pm, 8 July 2018, we heard loud crackling sounds, followed by breaks, crackling and thuds. Heather and I went over, using spotlights, and found that a number of branches of large valley oaks had broken off. I took these photos the next morning. It appears that five large branches fell, from three different valley oaks. A dominoes effect must have occurred, with one very high branch taking down another, high branch on a different tree, and they took out everything beneath them.
Although there are larger manzanita trees, this one is notably tall, approaching 20 feet, that Craig Konklin is standing next to. Located off Shaws Flat Road, Sonora, Tuolumne County.
Here are some details of the biology of the Pouch fungus, from Martin MacKenzie, Forest Pathologist, at the South Sierra Service Area of the Stanislaus National Forest, located in Sonora California.
“The fungus is Cryptoporus volvatus; the pouch fungus. It immediately tells you the beetles have flown. This fungus has a special adaptation that allows it to shed its spores in the heat of summer at the same time as the first wave (sometimes the only wave) of beetles are leaving the tree they have just killed. After the beetles (and blue stains) have killed the tree the Pouch fungus comes along and decays the sapwood of the now dead tree. The fungus has a special covering (volva) over its pore layer, this layer prevents the spores from desiccating in the heat of summer. The spores would not escape if there was not a pore at the back and on the underside of the conk. The sun heats up the air in the pouch the air currents carry the spores out of the pore and they blow in the wind until they encounter a fresh beetle exit hole. The spores germinate and grow down the exit hole, through the bark and begin to decay the sapwood.
As an experiment in scaling I scaled up the size of the microscopic fungus spore until it was as large as a 3 inch ball, then I scaled up a bark beetle exit hole by the same factor and found that it would be as large as a 50 foot culvert. Just as easily as I can throw a tennis ball into a 50 foot culvert, the fungus spore can fall into the hole left by an escaping bark beetle.
The 3rd slide in the attached PowerPoint might interest you. It’s of a Ponderosa killed by the western pine beetle and the areas of flecked off bark is where the woodpeckers were once going after the late larvae and pupae of the Western Pine beetle. That beetle moves into the outer bark before it finally escapes, to seek a new host. The woodpeckers pounce on the tree at this stage and do their bit to reduce the beetle population. But alas they do not take them all, they just make a living off them.
In this past couple of years I have seen what appears to be the pouch fungus fruiting just a few months after I realized that the tree was dead. The truth is there were a lot of trees out there, that were dead, they just did not know they were dead.”
The first photos (taken by Paul Cooper) are of dead, standing ponderosa pines, with the fungus fruiting bodies growing out of the tree. Lower photos are of a single mushroom, showing more detail.
Click on an image to enlarge it.
The California Manroot, Marah fabaceus, is a fascinating plant we find here in the Sierra foothills. A native vine, it produces a distinctive seed pod, covered in spines. Below are photos of the fruit, showing the seeds it produces. It appears to me that the fruit bursts open due to gas pressure inside. I failed to witness the actual opening, but shortly afterwards, I heard the seed pod release gas. This pod produced 17 seeds.
Click on an image to enlarge it.
This large valley oak lost a large branch at 10:45 pm, 25 June 2015, Gold Springs, Columbia Ca. We heard what sounded like gunshots, off and on for a couple of minutes, followed by what sounded like fireworks going off, before it became clear it was tree falling. There was no loud crash, however. Investigating the next morning, we found that a large branch of one of the giant valley oak trees had fallen, breaking a limb off an adjacent live oak, before ultimately landing in the crotch of the live oak, causing a big rift in its trunk. Click on an image to enlarge it.