Corbin Hill and the Dover Oak

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JHarkness
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Corbin Hill and the Dover Oak

Post by JHarkness » Thu Nov 29, 2018 8:23 pm

ENTS,

On this late November morning, me and my father paid a visit to some tree friends of ours on Corbin Hill in Pawling, New York. I have posted previously about part of the site, while the majority of the site was recently cleared for pasture, an extremely small amount of old growth is present between the pasture's edge and the margins of the Great Swamp. Unfortunately the old growth is even smaller than I originally thought, no more than a single acre, but both it and the adjacent second growth area boast a number of impressive trees. The site is notable given one of its dominant trees is the tulip, a species which is really pushing its luck in this area, as far as I'm aware this is the second northernmost naturally occurring tuliptree grove in eastern New York outside of the Hudson River watershed, the nearest individual tuliptree to this grove is over twenty miles away, as far as I know. I initially expected hemlock to be the tallest species topping out between 110 and 120 feet, while tuliptree would top out between 100 and 110, many of the trees here show signs of winter storm damage and seemed to me at the time, unable to get tall, much to my surprise the hemlocks ended up being shorter than I expected and the tulips much taller. I first discovered this site in April of 2017 on a hike along the Appalachian Trail with my father to the Dover Oak, a locally famous white oak which is claimed to be the state champion and the largest oak along the AT, I remember encountering a giant, dying hemlock, not super tall or super large, but its character stuck with me, and it stuck with my father just as much. I thought for sure it would be on the ground immediately, well, it has been nineteen months and it is still standing and doesn't look any worse.


Trees Measured:

Tsuga canadensis
106.1' x 10' 10"
103.5' x 11' 11"

Liriodendron tulipifera
130.1' x 7' 9"
126.0' x 8' 1"
119.6' x 6' 11"
118.1' x 7' 2"
114.0' x 7' 1"
112.2' x 7' 2"


As far as I know, the 130.1' tree takes the title of the tallest accurately measured tuliptree in eastern New York outside of the Hudson River watershed and north of the Dutchess/Putnam line.

IMG_5272.jpg
This is the tree which first caught my attention last year, it's not particularly large or tall at 11' 11" and 103.5', but the gnarled old tree sporting mushrooms, with broken off lower limbs, woodpecker cavities and a thinning crown give this tree a lot of character. I'm calling this tree the Swamp Hemlock because of its relation to the Great Swamp, which can be seen in the immediate background. It was a challenge to tapewrap given how the steep the slope it grows on is. 4.5' above mislope equaled approximately 8' above downslope. Additionally, 4.5' was too low for me to hit with the TruPulse so I had to raise it to 7.5' for it to be visible.
CorbinHillHM001_Panoramic.jpg
This photo captures the tree's character well, but it's not a great reference for its form, the tree actually has almost no taper on the lower two thirds of its trunk. Unfortunately, the tree is in serious decline, though I don't think it's going anywhere soon, it has held up to some really bad storms and doesn't look any worse than when I first saw it. The good news is that the decline is entirely natural, it is an old tree, I'm guessing that it is around 300 years of age given the historical land use of the site (which I won't go into in this post), but it could be even older. The retained lower limbs are simply because of the plentiful light on one side from the low canopy of the swamp and on the other side by the pasture which was once there, it ain't young. Fortunately, I didn't encounter any hemlock woolly adelgid on this visit, though quite a number of trees were showing decline due to elongate hemlock scale, the good news is that it is only present in low densities and is not present at all in some areas, as far as I know, the Swamp Hemlock doesn't have either.

IMG_5290.jpg
Near to the Swamp Hemlock is the tallest measured hemlock, a beautifully formed tree at 10' 10" in CBH and 106.1' tall, it has a significant lean but is in excellent health, it certainly has more growing left to do. These were by far the two largest girthed hemlocks but there probably are taller ones around, the second growth area adjacent to them has many tall "beanpoles" which are doing well and probably are pushing 110, maybe more. Unfortunately, the site has experienced a lot of blowdown recently, while the largest hemlocks made it, quite a few comparably sized ones did not. Additionally, a grove of hemlocks near the top of Corbin Hill is surprisingly tall and may have several taller trees, but that site experienced HWA die off in the early 2000s and has a nasty EHS infestation presently, though the tallest hemlocks are still doing well. For another visit, I suppose.



The tuliptrees were the biggest surprise, especially considering how young some of them were. The presence of black and yellow birches allowed me to pretty effectively gauge the age of the regrowth, I came up with 80-120 years, which makes sense as aerial imagery from the 1940s of the site shows an early successional forest still with some grassy/shrubby areas. The presence of a road in that imagery and the highly decayed stumps of about a half dozen northern red oaks suggests that it saw some logging around that time, likely it was high graded for red oak and white pine, explaining why Corbin Hill has almost no white pine but the adjacent swamp is full of pines. One thing I find interesting about the site is the species composition, tuliptree is a dominant species alongside hemlock, yellow birch and black birch, while sugar maple, beech and white ash are almost entirely absent, I did encounter several impressive beeches, two of which may be BBD resistant, but the sugar maples I saw were about a half dozen saplings on the edge of the swamp which a beaver had felled for food or dam/lodge construction. Comparing that to my property less than thirty miles away, tuliptree is entirely absent while sugar maple, beech and white ash are dominant species, scarlet oak, another species that I do not have, was abundant here as well.

CorbinHillTT001_Panoramic.jpg
The Split Tulip, the tallest at the site measuring 130.1' and 7' 9", still has a lot of growing left to do! I'm not confident that this is indeed the tallest, it is definitely one of the tallest, but there is a potential for a couple that are taller, none will exceed 140 and probably not 135. I don't know how to describe the experience of being in this tuliptree grove, while the trees aren't exceptionally large or tall for their species, there was certainly a feeling of being in a southern Appalachian forest, especially with the almost entirely tuliptree dominated slope above the flat were all of the measured trees are located. I almost found myself transported back the forests of West Virginia, a state which has a lot of family history for me.
IMG_5382.jpg
Looking up the trunk of the 126' tree. This is perhaps my favorite of the tuliptrees measured. It is truly a beautiful tree. Interestingly, it grows between the stone fence and the edge of the swamp, much like the two old growth hemlocks, obviously this tulip isn't that old, but it is older than much of the regrowth, perhaps this area was subject to earlier logging, I'd expect this tree to fall between 110 and 150 years of age.
IMG_5376.jpg
At 8' 1" in CBH, it was the largest measured tuliptree during my visit, however I do expect larger ones are around. I actually have a bit of mystery involving one of the largest tulips. Back in the Summer, I photographed an absolutely massive tuliptree that I guessed was roughly 12' CBH, I intended to measure it today but was shocked to see a ratty multi-stem red oak where I thought the tulip was, after a bit of searching I was unable to find it and gave up. I did however see a second large tuliptree which I did not measure, it is around 9-10' CBH.
IMG_5395.jpg
The third tallest tuliptree, 119.6'.


Leaving the tulips behind, we climbed to the ridgeline which makes up the summit of Corbin Hill, on the way we passed several respectable beeches, red oaks, hemlocks and the odd tuliptree. However, we were running short on time and didn't measure any. Reaching the top of the ridge, the forest changes dramatically, naturally the ridgetop is more oak dominated than the lower slopes, but the forest is young, shrubby and the marks of recent farming are very evident. Soon we left the forest behind entirely and started following the AT along the edges of several fields and through a couple natural wetlands. Here is a view to the north from one of the fields.
IMG_5330.jpg
After traversing several more fields and gradually descending off the ridge we entered the final field before West Dover Road, it is here one first sees the enormous crown of the Dover Oak. Here is a look at it.
IMG_5362.jpg
IMG_5336.jpg
Here are the statistics for this wonderful old tree.

Height: 82.7'
Circumference: 21' 5"
Average Crown Spread: 114.8' (spoke method)
Total Points: 368.4

I am confident I got the top of the tree, it was clearly defined and easy to hit with the laser, the tree is no taller, circumference was placed at the best representation of midslope I could find (while avoiding large knobs on the tree's trunk), however I fear my crown spread measurement may be a little lacking as I was only able to collect five spokes due to thick shrubs on one side of the tree, and a busy road on the other, I did however cover obvious extremes of the crown. Presently, these are best measurements for the tree.

Unfortunately, the tree has been the subject of multiple inaccurate claims of its exceptionality. It is listed on NY's Big Tree Register as having a circumference of 21' 1", an average crown spread of 128' and a height of 114'. The tree was measured and nominated in 2012, it has grown since then and there are many knobs on its trunk, affecting a circumference measurement, it has also seen crown reduction thinning since 2012, so the claim of 128' may not be inaccurate, though I wouldn't be surprised if the measurer didn't use a clinometer to ensure that they were indeed directly under a branch tip when measuring. The height is simply a gross overstatement. The inflated height and crown spread measurements give it a point score of over 390 points, so technically the tree can't be nominated as a state champion with its new measurements. I am going to give the regional DEC office a call soon to work the situation out and explain that my measurements are current and were done with a laser rangefinder and that the tree never was as large as it is listed as being on the Register. I'm just unsure whether I will be able to get an answer from them, or let alone whether I'll even hear back, knowing the troubles that many have experienced with them.

Additionally, the tree's age is also exaggerated by many, one source lists it as being 300+, while several others quote it as being 500+ or 600 years old, I encountered one which claimed that the tree is 660 years old. In reality it is no more than 300, the area was settled approximately 280-300 years ago, and this tree was almost certainly planted, it has been open grown its entire life. One large 3' DBH limb which was removed as part of the crown reduction thinning gave a ring count of 95, and that was thirty-five feet off the ground, depending on how fast it grew, it is reasonable to assume it is somewhere between 150 and 200, perhaps a little older.
IMG_5347.jpg
The tree is in excellent health, though it has experienced decline in recent years, it was thought for a while that it was "dying of old age", of course it was "over 600s years old", but finally it was realized that the decline was caused by soil compaction due to the area around the tree being used as a parking lot for the AT, not to mention the many times the tree had been hit by vehicles, it has numerous basal scars thanks to this. That was luckily changed and the tree has shown a noticeable improvement in health.

Curiously, the tree is not located in the town of Dover, but in fact one town south of there in Pawling, the name may have come from the fact that West Dover Road was once one of the major carriage roads leading into the town, perhaps it got the name as it was on the way to Dover.

In the end, me and my father were glad to have visited our tree friends on Corbin Hill again and to have recorded some actual data on their dimensions. We certainly didn't fully explore the site, follow up trips will be needed. Once I've purchased a reticled monocular I will probably make another visit to volume measure the two big hemlocks and any high volume tuliptrees, perhaps I will volume measure the Dover Oak as well.

IMG_5403.jpg
"Be not simply good; be good for something." Henry David Thoreau

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Larry Tucei
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Re: Corbin Hill and the Dover Oak

Post by Larry Tucei » Fri Nov 30, 2018 2:12 pm

Awesome post Joshua-
The Old Hemlock is really cool and the Tulips are Tall for that far north. I've only measured Hemlock in Wisconsin and some really tall White Pine. Tulip Poplar in their southern most range the Gulf Coast, have heights to 135' and 10'- 11' CBH. They are less than 100 years.
The Dover Oak is awesome and reminds me of the big Live Oaks down south! People down here over estimate the ages of the largest Live Oaks as well. One tree for example is the Angel Oak in South Carolina at one time it was said to be 1500. We now believe it to be in the 300 year range.
Larry

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JHarkness
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Re: Corbin Hill and the Dover Oak

Post by JHarkness » Fri Nov 30, 2018 3:19 pm

Thank you Larry,

It is interesting that you mention tulips exceeding 130' at the southern end of their range, I've been seeing a pattern at the northern end of their range where the northernmost sites top out right around 130, this site would be one, I believe Bob has several 130-footers in the Connecticut River Valley in western Massachusetts shortly before they drop off. I'm wondering if this is typically the case at both their northern and southern range limits, or is just a weird coincidence.

Despite being near the northern climatic limit for white oak here, and it not being a very common naturally occurring tree, it does surprisingly well in terms of maximum size, trees like the Dover Oak and Connecticut's Charter Oak come to mind. I've heard many claims that they reach 600, in some cases up to 1,000, but I suspect they rarely outlive 300, at least locally.

I've heard of the Angel Oak before and of its reported age, I never thought 1,500 was accurate, I'm glad to hear I'm not alone. Have any live oaks been core sampled? I'd be interested to know what the maximum age for the species actually is.

Joshua
"Be not simply good; be good for something." Henry David Thoreau

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Larry Tucei
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Re: Corbin Hill and the Dover Oak

Post by Larry Tucei » Wed Dec 05, 2018 8:13 am

Joshua- I've seen many examples of cut Live Oaks and recorded grow rates on avg. of .375" radial. I don't believe a Live Oak has ever been cored due to the density. Most of the ages have been estimated. Larry

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Erik Danielsen
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Re: Corbin Hill and the Dover Oak

Post by Erik Danielsen » Wed Dec 05, 2018 11:59 am

Josh,

Good work on the Dover Oak. It's been on my list to visit for a while. The discrepancies in height and crown spread are typical for large-crowned trees on the state champion list in the area. I've recently had some contact with the regional DEC forester in charge of certifying over there and he was quite interested in learning more about using ENTS-style measuring methods. Perhaps I can put him in touch with you.

The limb structure of the tree does obviously suggest that it's nowhere near 500 years old, but I wouldn't be quick to assume it was planted, either. Accounts of early exploration of the region certainly include plenty of mentions of open park-like areas with large oaks, some of which were probably due to topographic and natural disturbance factors, and others may have involved native american land use and periodic burning. The landscape had quite a mosaic of different types of woody cover. Such trees transitioned quite naturally into European-style land uses as settlement advanced. There are scattered sites throughout the region where other very old white oaks of similar form can be found (the Schoharie valley may contain the most examples of the sort that are most likely spontaneous in origin, being natural wind-pollards on the backside of high ridges). Following settlement, it's also true that many old "field trees" seeded in on their own and were allowed to persist and grow to be shade trees. Without specific dating or primary sources that really leaves us with three available narratives for their origin. Structurally this tree appears to be younger than the slightly smaller Bedford Oak.

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JHarkness
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Re: Corbin Hill and the Dover Oak

Post by JHarkness » Wed Dec 05, 2018 5:36 pm

Erik,

If you can put me in touch with him that would be excellent.

While there certainly is a possibility that this tree existed before the area was settled, I highly doubt it. I personally regard the many claims of the area being an "open oak forest" as being false, in the adjacent Hudson Valley there certainly would have been areas like this, and in some places there still are, but once out of the Hudson River watershed the forest composition changes dramatically, sugar maple, beech, yellow birch and hemlock become the dominant species and the number of oak species present decline, for example my town only has three native oak species, while a town just a few miles away in the Hudson River watershed there are seven species of oak present. White oak is one I find quite interesting, it is extremely common throughout the Hudson Valley, but the majority of the ones near here were from planted seed sources, or at least seeded in from isolated old growth survivors. On Corbin Hill there is no white oak except for in the immediate vicinity of the Dover Oak, probably less than three dozen trees in all, they all certainly seeded in from it, the farthest one from the Dover Oak I observed while I was there was less than a thousand feet away. I don't know the story to the west of there, as the area becomes drier and rocky, certain to grow a fair few naturally occurring white oaks.

A friend of mine at the Cary Institute of Ecosystem Studies has long been trying to work out where the idea of the "open oak forests" came from, what he has documented since is that all forests in the area that supposedly had a dominance of oak pre-colonial times were now dominated by shade tolerant trees and very little oak, the idea was that it was Native Americans managing the understory by burning, but apparently no such account of a Native American actually setting a fire in the area exists. He has suspected that this could be attributed to misidentification of trees by European settlers, one example is that the Cary Institute recovered documents for the site which showed the tree species composition, it was supposedly almost 90% oak and walnut, those "walnuts" turned out to be misidentified hickories, some species of birches and maples weren't even included and additionally "pine" was the only conifer referenced, yet the site now is hemlock, birch and sugar maple dominated. I personally don't believe that we can trust the accounts of early settlers in terms of forest composition on a scientific level, just as we can't trust the many overexaggerated tree size claims from the same time. To further the point, the account my town's historical society has of the area claims that the town's forests were "scrub oak and pitch pine", neither bear oak nor pitch pine are found anywhere in the town presently, and no appropriate habitat exists. Eastern red cedars are also directly mentioned in it as being a "dominant tree", they certainly are now on recently abandoned overgrazed pastures, but most are outcompeted and die out by the time they reach about 60 years of age, the only ones older than that which weren't directly influenced by humans occur exclusively on very steep talus slopes and cliffs. Another possibility I have thought of would be that perhaps there was a period of drought sometime within a couple centuries before settlers arrived which ultimately caused a large-scale wildfire causing oak forests to suddenly become dominant. The presence of hobblebush on my property also contradicts the idea that it was an oak forest with an open understory.

Apologies for the long reply, this has just been topic I've often wondered about.
Joshua
"Be not simply good; be good for something." Henry David Thoreau

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Erik Danielsen
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Re: Corbin Hill and the Dover Oak

Post by Erik Danielsen » Wed Dec 05, 2018 10:59 pm

Josh, your musings do get at the heart of the problem I tend to have with all sides in these (as mentioned, well-contended) discussions- the presumption that if we figure out what the dominant composition was, then we should dismiss the idea that any other communities were present as well. Given your climate and location, a majority shade-tolerant northern hardwoods/hemlock community would make sense to me as the dominant type, not unlike the uplands of my own area (which have only one oak species in most areas, and none at all in quite a bit)- but within that type's dominance the area still has heterogeneity with microsites hosting disjuncts (one of which is white oak, only showing up in small pockets in specific habitat- bur oak and red pine are some others). I don't think anyone regards historical accounts as valid to take directly at their word, but there is consistency (including with early botanists) that oak openings are a habitat type that was encountered even in many regions that are primarily in deep coniferous forest. I work a bit with an ecologist who's very (I believe excessively) focused on remnants of that habitat type, and I find myself objecting as well to his narratives about large areas of oak-dominant open forest because it seems likely that those habitats would have been sporadic and limited in extent, but being easier to pass through and more open would necessarily be more heavily featured in accounts of early travelers. It is a heavily biased sample- but there is no reason to imagine that it was a collaborative fantasy between strangers over centuries.

Of course open oak forests were not likely to be the dominant forest type in the area where the Dover Oak stands- to clarify my narrative, they were likely to be a sporadic and minor habitat type in that region at the time of early settlement, but were more readily transitioned to practices like grazing without strictly needing to cut down that big oak in the corner of the field, as compared to closed forest that all had to be cleared first. This same narrative is well established within the historic record further west in NY (some notable examples including the genessee valley, where all parcel buyers were contractually obligated to keep some portion of large oaks of that sort uncut), much of which was settled as much as a century later with much better quality of documentation. As a result, where these scattered large oaks did occur, they were sometimes more likely to remain standing than the deep-canopy timber that dominated the landscape around them.

Whether or not native american burning was the actual reason for the occurrence of such habitats is an interesting question but not necessary to establish that they existed, and of course similarly the presence of hobblebush (or 400-year-old hemlocks) in one spot doesn't indicate that there was or wasn't a wind-blasted bald on thin soil with a few hardy oaks spreading out a half a mile away. Going a bit further out than the last couple centuries, some major climate fluctuations in the last several thousand years are actually considered to be important factors in the seemingly mistaken distribution of a number of midwestern and prarie species up through the St. Lawrence and along the east coast into climate regions where they would not otherwise seem appropriate. White Oak distribution may be influenced by this to a degree but Bur Oak is probably an even more specific indicator at its range edges, extending into extremely harsh climates in the St. Lawrence valley, and with spotty distributions at least on the west side of the hudson on the high plateau that melds into the catskills.

All this is to say that while it's important to work to figure out the "bigger picture" of a given landscape's primary dynamics, to then assume that any small-scale deviation from that dynamic must be an artificial introduction is unnecessary. Given the proximity you state of Pawling to lowlands with more diverse oak communities, and the topographic complexity of the area as a whole and the continued existence of more natural open oak microsites in the region, the possibility that the Dover Oak originated spontaneously in one such microsite is necessary to consider unless there are records specific to that site or tree indicating planting or that that specific location had uniformly been closed-canopy forest.

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JHarkness
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Re: Corbin Hill and the Dover Oak

Post by JHarkness » Thu Dec 06, 2018 8:33 am

Erik,

I was referring to the "bigger picture" simply because of how many references there are of this whole region being in that forest type, I certainly think that there were isolated patches of such forest scattered all throughout the region, they just simply weren't dominant as so many people like to think. Unfortunately, I think a lot of that comes from romantic notion towards oak trees in this area, I don't know what it is but almost any landowner I've met in the area is practically in love with their oak trees, regardless of their species, size or health, the same is just not true for sugar maples or hemlocks or really any other species. I think regardless of what is actually growing in some place people around here want to be told that it is an oak forest, I believe that has resulted in a lot of the widespread accounts of this forest type in the area.

But regardless, there certainly were open oak forests scattered throughout the area. However, I don't believe that they were quite like many people claim they were being oak dominated, I've long suspected that they were actually hickory dominated. My neighbor has a small patch of mature forests on a small knoll on her property, the tree species are shagbark hickory with a scattering of northern red oak, the forest floor is densely covered in grasses and a few uncommon wildflowers for this area grow there, there is no understory, or midstory for that matter, and even before deer became an issue here, there was a dense understory nearby but no woody plants would grow here. I've often wondered if this was the kind of forest that settlers encountered and spoke of as "open oak forests", after all, they weren't aware of the hickory species so there is no reason not to think that they would have seen a co-dominance of oak species which they recognized and stated them as being dominant in those forest types.


In regards to the Dover Oak, I don't believe it was in such a site, it grows only three hundred feet away from, and twenty feet higher than, a stream. The dominant tree species in the forest around it are sugar maple, white ash, black cherry and to some extent American beech. The only white oaks are young trees all in close proximity to the Dover Oak suggesting they seeded in from it. There is a site on a nearby dry, rocky ridge where I would expect to see the same kind of "open oak forest", or perhaps open oak-hickory forest, but alas it is covered in birches, cherries and a few isolated red oaks, but they certainly aren't abundant. It is possible that the Dover Oak came into existence before settlers arrived, and if it did, I would expect it to be a young tree persisting in a canopy gap, seeded in from a second nearby higher ridge (two thirds of a mile away) which certainly has naturally occurring white oak.

Joshua
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Erik Danielsen
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Re: Corbin Hill and the Dover Oak

Post by Erik Danielsen » Sat Dec 08, 2018 12:31 pm

Thanks Josh, all these details add a lot of nuance to the context and potential origins of the Dover Oak.

Looking at your photos, its limb structure reminds me most of the "Granny Oak" in NYC's Pelham Bay Park. Sadly that tree blew over this past year. It was much too hollow for any dating. It had been subject to years of mischief and mismanagement- I'm glad to hear the Dover Oak has had improvements in its care over the years.

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addy
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Re: Corbin Hill and the Dover Oak

Post by addy » Tue Dec 11, 2018 6:02 pm

Larry Tucei wrote:Joshua- I've seen many examples of cut Live Oaks and recorded grow rates on avg. of .375" radial. I don't believe a Live Oak has ever been cored due to the density. Most of the ages have been estimated. Larry
Everything I could find on the topic of coring Live Oaks said the borer gets crushed or bent due to the very high density of the wood.

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