Six on Saturday: Native Range?

Valley oak, Quercus lobata, and Coast live oak, Quercus agrifolia, which I featured here last week, are the two formerly prominent native oaks of the Santa Clara Valley. I do not know if valley oak is native to the Santa Cruz Mountains above the Santa Clara Valley. It should be; and I should know for certain. However, I am not convinced. It is a chaparral species, not a forest species. The several old specimens in the Santa Cruz Mountains are on roadsides and in other situations where they seem to have been planted intentionally. Yet, this region developed mostly after the Great Earthquake of 1906, and not much was here prior to that, but some of the valley oaks seem to be a few centuries old.

1. A different perspective of the same valley oak from last Saturday conceals major storm damage that is otherwise so prominent. This really is a grand tree, in a perfect situation.

2. Although this is not a good picture, and does not seem to show much, it demonstrates how this tree is squarely centered within this view from the old depot baggage platform.

3. From the opposite side, the trunk obscures the baggage platform. Was it planted there intentionally? If so, why was it not centered on the window or doorway of the old depot?

4. It is just coincidence that the tree is situated so ideally on the edge of an area that was formerly used for parking? It was already old when cars still had horses in front of them.

5. Valley oak is such a grand tree. As big and sculptural as this specimen is, it is perhaps a century or so younger than the other tree. It was still quite small and shrubby in 1906.

6. Even the leaves are distinguished. The leaves of the trees in my former neighborhood had rounder lobes and sinuses. I do not know if such traits are environmental or genetic.

This is the link for Six on Saturday, for anyone else who would like to participate:

Valley Oak

Valley oak is the grandest of oaks.

From the north end of the Sacramento Valley to the San Fernando Valley, the valley oak, Quercus lobata, is among the most familiar and distinctive of native oaks. It is the largest oak of North America, reaching more than a hundred feet tall with trunks as wide as ten feet, which is why it is rare in urban gardens. The hundred fifty foot tall ‘Henley Oak’ of Covelo is the tallest hardwood tree in North America. The oldest trees are about six centuries old.

The two or three inch long leaves have deep and round lobes. The foliage turns only dingy yellow and then brown in autumn, and can be messy as it continues to fall through early winter, particularly since the trees have such big canopies. The gnarly limbs are strikingly sculptural while bare through the rest of winter. The gray bark is evenly furrowed.

Incidentally, Oakland, Thousand Oaks, Paso Robles and various other communities within their range are named for valley oaks. (‘Roble’ is the Spanish name.)

Valley Oak

Valley oak is also known as ‘roble’.

From the north end of the Sacramento Valley to the San Fernando Valley, the valley oak, Quercus lobata, is among the most familiar and distinctive of native oaks. It is the largest oak of North America, reaching more than a hundred feet tall with trunks as wide as ten feet, which is why it is rare in urban gardens. The hundred fifty foot tall ‘Henley Oak’ of Covelo is the tallest hardwood tree in North America. The oldest trees are about six centuries old.

The two or three inch long leaves have deep and round lobes. The foliage turns only dingy yellow and then brown in autumn, and can be messy as it continues to fall through early winter, particularly since the trees have such big canopies. The gnarly limbs are strikingly sculptural while bare through the rest of winter. The gray bark is evenly furrowed.

Incidentally, Oakland, Thousand Oaks, Paso Robles and various other communities within their range are named for valley oaks. (‘Roble’ is the Spanish name.)

Valley Oak

Valley oak is the grandest oak.

From the northern end of the Sacramento Valley to Santa Catalina Island, valley oak, Quercus lobata, is as Californian as Valley Girl. It inhabits mixed riparian forests and low hillsides up to about 2,000 feet, but prefers alluvial valley meadows in between. Although unpopular for landscaping, it sometimes self sows into home gardens. New landscapes sometimes develop around old trees.

Valley oak is one of the biggest of oaks, and the tallest oak of North America. Mature trees can be more than a hundred feet tall, and several centuries old. Trunks may be more than ten feet wide. Such big trees make big messes of acorns and deciduous foliage, which shed for weeks. Unfortunately, old valley oaks within new landscapes are susceptible to spontaneous limb failure and rot.

Where space is sufficient, new valley oaks are for future generations. They develop their distinctively sculptural branch structure slowly through several decades. If irrigation is not excessive, roots are remarkably complaisant. The evenly furrowed gray bark is rustically distinguished. The elegantly lobed leaves are about three inches long and half as wide. Yellowish autumn color is subdued.

Six on Saturday: Getting There Is Half The Fun

The biggest valley oak in the Santa Clara Valley supposedly lives next door to where I lived in town. Well, that was too far to go to get the picture I needed for the garden column next week. Another lives on the other side of the tracks.

1. Roaring Camp Railroad is out back. The Depot is out of view to the right, on the other side of Zayante Creek. The big valley oak that I got a picture of is on the left, but does not look so big from here. A few ecosystems mix here, so ponderosa pines, Douglas firs and all the riparian trees mingle with the coast live oaks and redwoods. However, I doubt that valley oaks are native.

2. Rhody stayed home. These grates on the pedestrian catwalk on the bridge are not intended for small paws. Some of those trees down there are about thirty feet tall! Most are white alder.

3. Riparian trees are close enough for pictures from a pedestrian bridge just downstream. That foliage in the middle of this picture is a sycamore. However, the deteriorating bridge is closed.

4. Old valley oaks, which are native just a few miles away, seem to have been planted here; since they all are on roadsides or driveways. Whether native or introduced, they happily self sow.

5. Moss makes these sculptural limbs seem to be older than they are. This now massive valley oak was a shrubby young pup in photographs from the 1920s. It was likely planted after 1906.

6. Gnarly roots were exposed by erosion on an embankment between the big valley oak and the train tracks. I suspect that the tree was planted to shade the depot during the late afternoon.

This is the link for Six on Saturday, for anyone else who would like to participate:

https://thepropagatorblog.wordpress.com/2017/09/18/six-on-saturday-a-participant-guide/

Horridculture – Vandalism

This would have been an ideal time for a seasonal update on the little Memorial Tree in Felton Covered Bridge Park. Until recently, it had been healthier and growing more vigorously than it had since it was installed a few years ago. It had survived major accidental damage, and was just beginning to thrive. Sadly […]

https://feltonleague.com/2020/06/28/vandalism/

via Vandalism — Felton League

Pin Oak

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Pin oak is not drought tolerant.

There are several oaks, especially natives, that do not need much more water than they get from rain. Pin oak, Quercus palustris, is not one of them. It is naturally endemic to areas that are damp or swampy for part of the year. It is more tolerant than others are to lawn irrigation, but is also more sensitive to drought.

Compared to other oaks, pin oak grows fast while young. It can get two stories tall in about ten years. Then, it takes more than twice as long to double in size. Old trees do not get much more than fifty feet tall, with trunks nearly three feet wide.

The deciduous foliage turns as brown as a grocery bag in autumn, and may linger late into winter, or until it gets replaced by new foliage in spring. The distinctively deeply lobed leaves are about two to five inches long, and about two thirds as wide. Each leaf has five or seven lobes. Each lobe has five to seven teeth.

SODS?

P00202
Flagging (sudden necrosis of distal foliage) used to indicate the beginning of a sudden end.

Phytophthora ramorum is the pathogen that initiates Sudden Oak Death Syndrome, which is known simply as SODS. Monarthrum scutellare, which are known as ambrosia beetles, and are the secondary pathogen associated with the syndrome, infest and kill tanoak and coast live oak that are infested with Phytophthora ramorum, about as quickly as symptoms are observable.

Hypoxylon thouarsianum is a tertiary but merely opportunistic pathogen associated with the syndrome. By the time it gets established within galleries excavated by the ambrosia beetles, the affected trees are almost completely necrotic. That first ‘S’ in SODS is there for a reason. It is an efficient process. Death occurs too suddenly for affected trees to drop any of their leaves!

Each of these three pathogens causes distinct symptoms. Phytophthora ramorum causes trees to bleed black tar-like fluid, and causes tanoak to exhibit foliar flagging as seen in the picture above. Monarthrum scutellare expels finely textured frass from the galleries it excavates into infected trees. Hypoxylon thouarsianum produces distinct small and black fruiting structures.

In the past several years though, Sudden Oak Death Syndrome has often been a bit less than sudden. There are a few tanoaks here that have exhibited foliar flagging for a few consecutive years, without any bleeding from the trunk or infestation by ambrosia beetle. Some coast live oaks have exhibited minor bleeding, but likewise have not become infested by ambrosia beetle.

It is as if the ambrosia beetle is no longer proliferating as it had been. It actually seems to be rather scarce. Trees that were expected to succumb suddenly to ambrosia beetle infestation are succumbing slower to infestation of only Phytophthora ramorum. The process is variable, so might have potential to kill some trees rather suddenly, but may take a few years to kill others.

Could some possibly survive?

Props

P90901It has been almost a month since one of three small but sculptural and very prominent coast live oaks at work was destabilized by . . . well, children. They were climbing on it, as most good children should do. There were a few of them; and the tree is old and deteriorating. All three of the trees actually grew from the same rotten stump of a tree that was cut down decades ago.

I wrote about it at ‘Six on Saturday – Do Not Sit On Tree‘. The title will make more sense if you read about it.

To salvage the tree, I pruned off as much of the foliar canopy as possible. This eliminated some of the weight that the trunk needs to support, as well as decreased some of the resistance to wind, which exerts leverage against the compromised root system when wind blows. Sawhorses were placed under the trunk, and one of the others, to prevent them from sagging any lower.

Props that were fabricated to be more permanent then the sawhorses were installed last week. They do not actually support or even touch the trunks, but are there to prevent the trunks from sagging any lower. If the trunks start to lean on the props, I will prune a bit more weight off. If that doesn’t work, the props can be moved a bit farther out, where the trunk are higher.

Hopefully, the old root system of the destabilized tree was not so severely damaged that it can not recover. If it does recover, and the trunk is not supported by the new prop, the tree will need to eventually regain stability. It will be a tediously slow process. Because the trees are already so mature and disfigured, the props will likely never be removed, regardless of recovery.

The first picture above show the destabilized tree outfitted with a new prop. The second picture below shows the other tree that was outfitted with a new prop just because it is so likely to become destabilized.

P90901+

Six on Saturday: Do Not Sit On Tree

 

1. Seriously!P90810

2. Allow me to explain. This is one of three small but very gnarly coast live oaks that grew from the roots of a single tree that was cut down or fell several decades ago. Because the trunks of the three trees are so horizontal and sculptural, children climb on them. Sometimes many children sit on the trunk of this particular tree to get their group picture taken. We had been concerned about how this might compromise the stability of the tree for quite a while. Before we constructed suspension devices to prop it and one of the other two trees with, it destabilized and sagged! We pruned much of the canopy away to eliminate some of the weight that exerts so much leverage against the root system, and propped the trunk with a saw horse. We hope that the tree survives the loss of roots that likely broke away in the process, but would not be surprised if it does not. We are not ready to cut it down. It and the two other trees are so well known and popular among guests. The sign is visible to the right. I will explain the colored yarn on the trunk in a moment.P90810+

3. The subject tree is to the lower right in this picture. The two other trees are sprawled to the upper left. The tree that extends farthest to the left will get propped as well. All three have been pruned more aggressively than they should have been to eliminate much of the weight.P90810++

4. The yarn on the trunks is decoration that the camp counselors installed prior to the arrival of the guests. It must have taken a long time to wrap this much yarn around the trunks, and there is a whole lot more in many other trees. I wrote about it earlier in ‘Boom! Zap! Wow! Bam! Zing!‘.P90810+++

5. This is a completely different coast live oak, with a completely different problem. It needed to be pruned for clearance from an adjacent roadway and walkway. The major limb that was here supported less than one tenth of the total canopy, but because it had been cut back repeatedly, it was unusually bulky. Consequently, the shiner that remains is about as wide ad the remaining trunk! That is VERY arboriculturally incorrect. To make matters worse, the cut was not at the correct angle, so eliminated the lower half of the ‘collar’ that is supposed to expand to compartmentalize (heal) the shiner. The problem now is that by the time the shiner heals, the interior of the trunk may be so rotten that the tree may need to be removed anyway. The limb needed to be removed. The only other option was to remove the entire tree.P90810++++

6. Nothing was done to this coast live oak. It grew like this naturally. Although not an exemplary specimen, it certainly is impressive.P90810+++++

This is the link for Six on Saturday, for anyone else who would like to participate:

https://thepropagatorblog.wordpress.com/2017/09/18/six-on-saturday-a-participant-guide/