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We had a wonderful Field Course in Lexington, a tour of some of Lexington’s finest trees. Our friend Erin Barnhill was kind enough to share some of her photos of the trip.
Lexington is home to an astonishing number of very large, very old trees. Many of these trees were here before the city was settled and represent the original vegetation of the Bluegrass. As the city grew, the native woodland pastures were cleared for development, but the finest trees were often kept in yards, parks and even in industrial areas. Please join Venerable Trees for a guided tour of Lexington’s finest trees on Saturday, October 14.
Here are a few of my favorite Lexington trees.
Until recently, we have been telling you that blue ash, Fraxinus quadrangulata, appears to be resistant to emerald ash borer, Agrilus planipennis. This is important because blue ash is the most abundant ancient tree in our woodland pastures. The emerald ash borer is devastating our white and green ash trees. See our previous story about the green terror.
Now, we need to revise that preliminary conclusion. We recently found a large blue ash that was riddled with the D-shaped holes. These holes are created by the adult beetles as they emerge from the tree in the spring. This particular tree, shown in the picture, had more holes than we have seen in any other ash tree. However, the trees around this one had not been attacked. Why was this one tree attacked while others were left alone?
We have one hypothesis which remains to be tested. In China, where the emerald ash borer is native, healthy ash trees are entirely resistant to the borer. Only stressed trees are attacked and killed by the borer. We think that the same thing may happen with blue ash in North America. The tree that was heavily attacked appeared to be under stress, possibly from mower damage. Blue ash is physiologically and genetically very different from other North American ash trees and it seems to be highly resistant to emerald ash borer throughout its range. Emerald ash borer may kill stressed blue ash trees but leave healthy ones alone.
Only time will tell if we are right. We strongly recommend taking better care of blue ash trees. Avoiding mower damage, soil compaction and other stressors may allow our blue ash to survive the onslaught of the green terror. We do recommend treating high-value blue ash trees until we are more certain.
The Lexington Herald-Leader published this aerial photograph of the future Fayette Mall in 1967. The photo clearly shows and extensive woodland pasture, with a mix of large, old trees and smaller hedgerow trees. Today, only a single tree, the Tiverton Oak, remains of this woodland pasture. Fayette County has lost a tremendous number of trees to development. We found that over 90% of bur oaks have disappeared from Fayette County in the last 60 years (see Venerable Trees: History, Biology and Conservation in the Bluegrass).
Today, our efforts are focused on preserving the current Urban Service Boundary of Fayette County. If we are to avoid further loss of our ancient trees and precious ecosystem, we need to continue to focus development on infill and redevelopment inside the current development boundary.
The next Venerable Trees Field Course, on Saturday February 4, will address the issues of urban/rural boundaries and development.
The margin between urban and rural areas is an area of constant change. In most cities, development rapidly gobbles up rural land, including its forests. In Lexington, Kentucky, strict land use regulations have slowed this trend. It is at the edge of the city that we can most closely watch and learn from the impacts of development and other land use changes on our Venerable Trees.
Please join us on Saturday, February 4 as we explore the city’s edge. We will explore the fascinating Coldstream complex, a diverse area of developed and agricultural land that is home to a remarkable population of ancient trees. Katherine Shaw and Tom Kimmerer will tell the fascinating history of the area, and we will together explore the unique biology of these ancient trees and their habitat. We will also help you hone your winter tree identification skills.
Registration is required, but there is no fee. To register, send an email to email@example.com, and provide your name, number of people in your party, your email, and a phone number where you can be reached. We will then send you detailed information about the course. Right now, the weather forecast is for temperatures in the 50s and overcast. If that changes for the worse, we may reschedule the course.
People of all ages are invited. The walking will be easy, and the terrain not very rough. Children are welcome with adult supervision. Well-behaved dogs on a leash are also welcome, though cats and parakeets are not.
We hope to see you on the fourth.
The urban forest of Lexington includes a remarkably large number of very large, very old trees, may of them predating the existence of the cities. These trees are now in trouble. Many of them are unhealthy because of neglect, poor management decisions, and old age. We need to change the way we view and manage these old trees or they will soon be gone. Please join us for a discussion about the actions we can take to ensure a long life for these trees:
Lexington’s Urban Forest: Remnants of an Ancient Landscape, Wednesday September 7, 6-8 pm, Fayette County Extension Office, 1140 Red Mile Place, Lexington. Open to the public, no registration. Map.
The benefits of large trees in urban landscapes greatly exceed the benefits of smaller trees. Very large trees provide wildlife habitat and other ecosystem services that cannot be replaced when they die.
Yet in most cities, including Lexington, almost all the expenditures of money, time and effort in urban forestry are misdirected. We spend huge amounts of money planting street trees that repay the favor by quickly dying. Conversely, we spend almost no money on large old trees except to take them down.
We need to change the way we think about and manage large old trees before they are all gone. On September 7, 2016, we are going to begin a series of events designed to change the way we practice urban forestry and avoid the loss of all our ancient venerable trees.
This discussion will be followed by a Field Course on Saturday October 1 to explore the presence and management of ancient trees in our landscape. Registration is required for the Field Course. More information is on our Field Courses page.
The goal of these events is to ask and answer one question: how do we ensure a future for our ancient trees? To make these events successful, we need you. We are inviting community leaders to these events, but it is very important to have a good showing of our loyal friends and supporters. Please make a date to attend the events, especially the lecture on Wednesday September 7.
Fayette County, Saturday October 1, 9am-12pm. This course will focus on urban remnants of the original woodland pastures of the Bluegrass. We will begin at Veteran’s Park, a fascinating mix of very old woodland pasture trees and woodlands that have since become established. Our walk will include the famous Veteran’s Oak, and we will examine the factors that threaten its health. We will also explore the Wood Wide Web, the interconnections among trees that allow forests to remain healthy and vigorous. Time permitting, we will explore a residential neighborhood that includes an extraordinary number of woodland pasture trees.
To register for this Field Course, click the button below. The cost is $20 per person, $5 for students, including graduate students and postdocs. Children accompanied by an adult are welcome, and there is no charge for children. Well-behaved dogs on a leash are welcome; cats and parrots are not.
Venerable Trees, Inc. offers frequent Field Courses to introduce people to the amazing woodland pasture ecosystem of the Bluegrass and Nashville Basin. Recently, we were able to visit the amazing Airdrie Stud Farm at the gracious invitation of Mrs. Elizabeth Jones, the Owner. Airdrie Stud is one of the premier horse farms in the Bluegrass. It is also the location of one of the best-preserved and most extensive woodland pastures and some of the finest trees in the Bluegrass.
Below is a slide show of our course. The photos were taken by Rick Showalter and are used with permission. Thanks Rick and Sallie! Click pictures for a slide show.
When you hike through the woods in Nashville, you don’t expect to encounter wolves. If you keep your eyes open, though, you may see some wolf trees.
Foresters used the term ‘wolf tree’ to indicate a very large tree with a broad crown and a short main stem. These trees were considered wolves because they were so large that they devoured sunlight that other trees might need. These trees were often killed because they had no market value.
Today, we have a changed opinion of these huge trees. They are now understood to be very important as wildlife habitat and also in regenerating a new forest after harvesting or damage. Harvesting rules, especially on state and federal forest land, often require that wolf trees be left in place.
Wolf trees serve another important purpose: they can tell us a lot about the history of a forest. On a recent walk through the Warner Parks of Nashville, I noticed something striking. Throughout these hilly, dense woods were many huge wolf trees. A closer inspection showed that these were species typical of the woodland pasture habitat: chinkapin oak, Shumard oak, blue ash, and kingnut (I have not yet seen any bur oak).
Their enormous size and low, spread branches tell us that these trees did not grow up in a forest, but in either an open woodland or woodland pasture. The level ground surrounding the Warner Parks has a large number of woodland pasture tree species and several intact woodland pastures. I suspect that this part of Nashville represented a continuum from woodland pastures on level ground to open woodlands and the slopes and denser forest on the upper slope.
The Warner Parks are about to lose their large population of white ash to emerald ash borer. I made a quick estimate of the stocking (timber density) of white ash in the Warner Parks and estimated it to be more than 20%. As these trees die over the next few year, conditions may favor the ability of the wolf trees to reproduce.
I look forward to learning more about this beautiful area.
Everyone wants to know how old a particular tree might be. We will discuss this complicated and important subject in two stories. This month we will talk about unitary trees, and next month we will tackle the complex problem of aging clonal trees.
A unitary tree is like a person – a single, integrated organism. Unitary trees have one or a few stems on a single root system. The stem is the same age as the root system. Most tree species are unitary, although some, such as oaks, beeches, and red maples, will create a new stem or a few stems when the original one is lost so that the root system is older than the stem.Clonal trees are colonies of many stems, sometimes thousands, on a single root system. The entire clone, including all the stems and the root system, is a single organism. Over time, some root connections may be lost and the tree no longer functions as a single organism, even though the separated parts are genetically the same as each other.
Clonal trees are colonies of many stems, sometimes thousands, on a single root system. The entire clone, including all the stems and the root system, is a single organism. Over time, some root connections may be lost and the tree no longer functions as a single organism, even though the separated parts are genetically the same as each other.
As most of us know, trees in temperate climates generally produce a single ring of wood each year, growing fast in the spring, slowing down in the summer and producing a distinct ring. It should be a simple matter, then, to count the rings and find out the age of the tree. We can do this either by cutting the tree down or by taking an increment core, a narrow cylinder of wood from the bark to the pith at the center of the tree. This is not as simple as it sounds. Obviously, we don’t want to cut down ancient trees unless they are dead or in danger of falling and doing harm. Increment cores are very labor intensive both to obtain the wood sample and to prepare the sample and count the rings. Very large trees like our bur oaks are extremely difficult to core.
Determining the age of an old tree by carefully counting and cross-dating the rings using valid methods, followed by publication of the results in a peer-reviewed journal is the gold standard for determining and confirming the age of a tree. On that basis, the oldest known tree in the world is a bristlecone pine, Pinus longaeva, originally collected by Ed Schulman in the 1950s but only analyzed by Tom Harlan in the past couple of years. This tree, now 5065 years old is still alive and growing well in the White Mountains of California. Understandably, its location is kept secret. This tree is accepted as the oldest unitary tree known in the world.
In the Bluegrass and Nashville Basin, the majority of our very old trees are hollow. You can’t count the rings in a hollow tree unless you take a sample above the hollow part, and then you may miss many years of growth.
In Europe and Asia, the age of very old trees may be known from historical records, such as the date a yew tree was planted in a churchyard, or a sacred bodhi tree was planted at a temple. We rarely have that luxury in North America with its very short written history. A number of trees planted by Thomas Jefferson, William Bartram and other botanists and enthusiasts survive today and we can date them precisely. William Bartram planted a yellowwood (Cladrastis kentukea) at his garden in Philadelphia in 1805. Badly damaged by a wind storm in 2010, the tree recovered and is thriving today at age 210.
Any other method of determining the age of a tree is very imprecise. The relationship between tree size and age, especially in our open-grown hardwoods, is not a strong one. Trees growing slowly in poor conditions often outlive trees in better conditions.
Over time, a number of biologists have developed criteria to assess whether a tree is very old. Neil Pederson summarized the most important characteristics of very old hardwood trees: 1) balding bark – bark smoother than younger trees of the same species; 2) low stem taper – the main stem is cylindrical, not narrowing with height; 3) sinuous, winding stems and branches; 4) crowns with few, very large and twisting branches; 5) low crown volume relative to the stem diameter; 6) low leaf area to trunk ratio. For the ancient trees of the Bluegrass and Nashville Basin, two additional characteristics are 7) leaves tufted at the ends of branches; and 8) main stem rarely present, with the top of the tree damaged and decayed. While these sound complicated and difficult to analyze, with a little bit of practice, it is not difficult to separate our oldest trees from younger ones.
Using these criteria and a knowledge of the terrain and land use history, we can usually sort our trees into categories. For example, an extremely large bur oak growing at the top of a slope that shows the above characteristics was probably growing before the area was settled. That would make it somewhere in the range of 300-500 years old, possibly older (we have found some older trees but have not yet published the data). A bur oak of similar size, growing along a creek with good access to water and showing fewer of the old-tree characteristics may be half the age of the one at the top of the hill.
I know this answer frustrates a lot of people anxious to know the age of their favorite trees, but the plain answer to “how old is my tree?” is usually “I don’t know but I think it is several hundred years old. Based on the limited scientific evidence that we have, plus some historical data, I am often comfortable saying that our biggest old trees are “probably 300-500 years old, maybe older.”
And as to all the claims of the great age of trees that we see on the Internet, we should treat them with a great deal of skepticism. That 6,000-year-old baobab? It might be 1,000 years old. The Angel Oak said to be 1,500 years old? More likely to be 400-500 years old. These trees are still very old and deserving of our respect and veneration, and there is really no good reason for people to make such wild claims. And what about that 9,000-year-old spruce called Old Tjikko, the subject of thousands of Facebook claims and blog posts? As we will see in our next story on old trees, that claim does not hold up either.
Venerable Trees, Inc., is focusing our efforts on five high-priority geographic areas and four high-priority tasks:
Today, we are launching a new project “Great Trees of the Bluegrass” to locate and identify important trees in our region. We have a new Facebook Group: Great Trees of the Bluegrass for you to contribute your own observations, and we are also creating a new web-based identification and mapping tool for your use. The purpose of this project is to identify, map and evaluate the important trees of the Bluegrass and to tell their stories. We will later be extending this to the Nashville Basin.
The Great Trees are based on my book Venerable Trees: History, Biology and Conservation in the Bluegrass. The Bluegrass is home to the largest number of ancient hardwoods – trees that predate the existence of Lexington, of Kentucky, and even of the United States.
The criteria for listing Great Trees of the Bluegrass are: 1) the tree should be native to the Bluegrass; 2) the tree must be publicly available – either on public property or accessible to the public; 3) the tree must be old and large – we will start with a minimum of 100 inches circumference (32 inches diameter). Of course, we don’t know how old most of these trees are, but we can recognize the very old ones that are likely to predate the establishment of Lexington in 1779.
To get us started, here are 10 of Great Trees of the Bluegrass. Each tree will eventually have its own page. For now, the link will show you a larger version of the photograph.
The Ingleside Oak on Harrodsburg Road near Red Mile
The St. Joe’s Oak
The Henry Clay Basswood
The Castlewood Park Giant Blue Ash
The Kissing Tree at Transylvania University
The Coldstream Bur Oak
The Veteran’s Park Oak
The Kirklevington Oak
The Old Schoolhouse Oak
You may recognize the bur oak in this page from previous photos. It is a magnificent, ancient bur oak in Kirklevington Park. I visit it often. Last week I was looking at the tree in the late afternoon and noticed a few leaf fragments on the ground. The next morning, I came back and saw that the tree had been totally defoliated overnight, stripped of nearly every leaf. After a few days, it began to refoliate – to produce a new crown of leaves. Spring defoliation is very common, but is not very harmful to hardwood trees.
None of the nearby bur oaks were defoliated. Two Shumard oaks had lost a little bit of foliage. It was like a special forces strike on a single tree. Remarkably, the defoliating insects were completely gone by morning, not a sign of them. I don’t know what they were.
We’ll add more pictures as recovery continues.
Click pictures to enlarge or for a slide show.
If you go to Lexington or Paris farmers’ markets, you may know Oakland Farm, “Home of the $10 Tree” Tim Diachun, our business manager, and I spent a wonderful afternoon at the farm with the owners, Doug Witt and Laura Greenfield.
Oakland Farm is not named for the trees they grow in their nursery, but for the absolutely spectacular woodland pastures that meander through the 700+ acre farm. Oakland Farm is a multi-generation family livestock farm, in operation since 1876. Last year, Doug and his niece Laura began a small tree nursery, growing seedlings of native Kentucky trees for the local market. They are filling a very important market need for seedling trees, and we will have much more to say about that in the near future. For now, we want to focus on the woodland pastures.
Many Bluegrass farms have woodland pastures of ancient trees that predate the settlement of the region. What stands out about Oakland farm is not just the large number of trees but the incredible character of each one. These trees are very old and have taken on the typical appearance of very old trees – gnarled branches, many of them broken, the stems often leaning because of shifts in the soil. Rather than just tell you about them, we’ll let you feast your eyes on them.
We really appreciate the enthusiasm of Doug and Laura both for their ancient trees and for their new tree nursery. Our hope is the Venerable Trees and Oakland Farm are beginning a long and mutually beneficial relationship.
Scroll down to see more pictures of Oakland Farm’s amazing trees.
Finding left-behind trees can be the start of an urban adventure. As our woodland pastures were developed into urban areas, most of the trees of woodland pastures were cut down. A few remained, usually as single trees in a parking lot or front yard. Here’s where the adventure comes in: when we find a single tree and take some time wandering around, we often find more.
So it is with the Ingleside Oak on S. Broadway in Lexington. I have known this tree for many years, but only recently took the opportunity to wander the neighborhood near the tree. The search was rewarded, as we found about a dozen trees representing the original woodland pasture trees of Ingleside Manor.
Clusters of trees are found in other areas as well. In Ecton Park are two old blue ash trees, but the neighborhood around the park has over a dozen trees in front and back yards.
The next time you find a Left-Behind Tree, we hope you’ll take the time to look around for others. And be sure to tell us about them.
The Veteran Oak in Lexington is one of the most iconic trees in the city. A magnificent bur oak, it lies along a popular walking path on the south side of town. The Veteran Oak is a left-behind, the only ancient tree in a young riparian (stream-side) forest. Most of the ancient left-behind trees are on dry uplands, like the Old Schoolhouse Tree. The Veteran’s Park Oak is on a stream bank and benefits from high soil moisture and intermittent flooding.
The tree is in excellent condition. It has a few dead branches and lost its top at some time. This is normal for very old trees, and the dead branches and hollows provide habitat for a wide range of animals and fungi. Young trees around the old oak are beginning to grow into its canopy. Sometime soon, in the next few years, we will need to thin the trees around the Veteran’s Park Oak to give its lower crown more sunlight. This technique of removing smaller trees to concentrate growth on larger trees is called ‘thinning from below’, also sometimes called ‘haloing’, though I prefer the former term. The path that goes by the tree on the creek side is causing some soil compaction, and should be closed.
Here is a photograph of the entire tree. This is a composite of 36 individual photos stitched together.
A left-behind tree is our term for woodland pasture trees that are left behind as lone individuals when farmland is urbanized. You can help us find them.
Woodland pastures are part of the original presettlement vegetation of the Bluegrass. As some areas, especially in Fayette County, were urbanized, most of the trees of the woodland pastures were felled. Throughout our urban areas, though, a few hardy individuals remain. They are often in odd places – in a parking structure or an industrial lot. Few of these trees get proper care, and many are in decline. Yet, given enough space, these trees can thrive and remain in the city for centuries.
We would like to hear from you about left-behinds that you have seen. We would like to locate and map every left-behind tree in urban and industrial areas of the Bluegrass, and work to preserve them. There are three ways you can let us know – by using our Contact form, by emailing info (at) venerabletrees.org, or the best way, which is our Facebook page. Please be as precise as you can be about the location and the species if you know it. Include a picture if you can. Smartphone pictures usually have the GPS location embedded, and those are the most useful. Don’t worry if you are uncertain about the species. We are looking for trees which, in your mind, are very large and old. We will create a map of all your submissions (if the location is accurate) and eventually evaluate them.
Right now, we have about 200 mapped in Lexington, Danville, Paris, and Midway. We would love to double that number.
Dead trees are fascinating because they provide us with a permanent record of their lives. The annual rings that record the tree’s experience with drought, nutrients and temperature are familiar to most of us. Somewhat less familiar, but easy to see, is the record of all the insults, accidents and stresses of life as a giant, long-lived organism.
The photos in on this page are from a very old blue ash (Fraxinus quadrangulata) that died and fell over a few years ago. As the bark decayed and sloughed off, the wood was exposed, showing us the most recent wood made by the vascular cambium. The cambium is an amazing tissue. It is a continuous sheath of stem cells that lie between the wood (xylem) and inner bark (phloem). All the wood in the world is made by the cambium of trees. The stem cells of the cambium are constantly adjusting their cell division to make the appropriate amount of wood and phloem, and to react to changes in their environment, including gravity, wind and wounds.
I think that the cambium serves as a pressure sensor – the pressures created by the wood to the inside and phloem to the outside, combined with pressure changes due to wind and gravity, determine what kind of cells the cambium produces.
The wood just below branch junctions is heavily wrinkled. This represents the combined influence of gravity and wind. The branch constantly flexes in response to wind, and the cambium below constantly adjusts to stabilize the main stem. On the main stem, the ripples in the wood are also probably due to wind and gravity, but are more subtle. These surface ripples are reflected deeper in the wood, and lead to the figure so highly prized by woodworkers.
Once the tree is dead and down, and the cambium is dead, other processes begin. Wood is under tremendous stress and strain in a living tree. As soon as the tree dies, the wood begins to crack as its moisture content changes. The cracks provide easy entry for decay fungi, protists and insects. The holes in the wood are made by beetles that feed on dead wood. Many of these beetles carry fungi with them that accelerate decay. Over time, insects, bacteria, protists and fungi gradually take the tree apart, converting the wood to energy and biomass. How fast this happens depends on temperature and moisture: in moist tropical forests, a tree may disappear completely in a few months. In drier or colder forests, complete decay may take centuries or may never happen.
The process of death, decay and recycling is critically important to forest health and stability. Without decay, nutrients would not be returned to the soil and be made available to the next generation of trees. Wood decay enriches the soil.
Update: In response to some questions, we have added a description of differences between Northern red oak, Shumard oak and riparian oak at the end of this article.
Near Ashland in Lexington, we found a beautiful, large riparian oak. Riparian oak is a hybrid between Northern Red Oak, Quercus rubra, and Shumard oak, Quercus shumardii. Its Latin name is Quercus x riparia or Quercus rubra x shumardii. The letter x indicates a hybrid.
What makes this a hybrid? Some of its features look like Northern red oak, including the bark, the size of the leaves, the size of the acorns and some features of the buds. Other features look like Shumard oak, including the leaf lobes and some features of the buds.
This tree is growing behind a house near Ashland, the home of Henry Clay. In the 19th century, this tree was on the Ashland estate property. It does not bear the characteristics of a very old tree, and I suspect that it was planted on Henry Clay’s estate. Clay planted a large number of trees on his estate, and it is possible that this tree was one of them. In the early 19th century, it was common to collect trees from the wild for transplantng into estates. This tree may have grown somewhere else before transplanting. This is all based on an educated guess – without knowing the age of the tree, we can’t determine its origin.
Hybrid oaks are common throughout the Bluegrass, especially in the red oak group. Some forests, such as Quiet Trails State Nature Preserve in Harrison County, seem to consist mostly of hybrid red oaks. Shumard oak hybrids with pin oak, Northern red oak, shingle oak, and black oak, among others.
Differences among the oaks
Tom Eblen has a fine article in today’s Lexington Herald-Leader about the Old Schoolhouse Oak and the commitment of Ball Homes to preserve the tree in a new housing development. By my count, this is the 14th Herald Leader article about this splendid tree
Bur oak in the Bluegrass reproduces only rarely. Although it is a prolific seed producer, there is very little suitable habitat for young bur oak trees.
While inspecting our preservation work on the Old Schoolhouse Oak with Tom Eblen of the Herald-Leader, we noticed several vigorous young bur oak seedlings. These trees are just outside the tree protection zone, and we have marked them to keep. They will eventually become shade trees to add to this new development – we may leave them in place or transplant them to a suitable location.
Click on the pictures for a gallery of images of the Old Schoolhouse Oak.
The Inner Bluegrass has long claimed the title of Horse Capital of the World. Early farmers found that our water and soil produced the ideal conditions for raising horses. Today, there are over 400 horse farms in the area. Many of the most distinguished farms have been in the same families for generations. For these farmers, good stewardship of their land is the secret to success in raising great horses. The trees of Horse Country are an integral part of farm operations, and many of the land owners are concerned about the future of the trees on their farms.
Many of the farms of Horse Country include intact woodland pastures, where large, open-grown trees have shaded the grass for hundreds of years, long before there were any farms. These woodland pastures, created by drought and bison, became the farms of today. Take away the fences, barns and homes, and many of these woodland pastures would look much like they did in 1779, when Lexington was settled.
Other farms have lost their woodland pastures over time, or did not have them in the first place. These farms often have extensive tree plantings in tree pens and along roads, as well as natural hedge-rows of trees along property lines and creeks.
The beautiful landscape of the Bluegrass would be sterile and uninteresting if not for the trees. They are an integral part of Horse Country. We need to do a better job of selecting appropriate trees and planting them in appropriate places if we are to ensure a long future for the Trees of Horse Country.
For a slide show of the Trees of Horse Country, click any of the pictures. Over the next few months, we will be featuring more of the Trees of Horse Country
Runnymede Farm in Bourbon County is the oldest continuously-operated thoroughbred farm in Kentucky. Founded in 1867 by Colonel Ezekiel Clay, it is today operated by his grandson, Catesby W. Clay, and great-grandson Brutus J. Clay III. As you might expect for such a long-running family farm, the Clay family has taken great care of their land, including many venerable trees. Runnymede is most famous for its horses, and has played a key role in the foundation of the thoroughbred industry. We, of course, were attracted to Runnymede for its venerable trees.
Brutus Clay, the President and fourth generation farmer of Runnymede, was kind enough to show us around the farm on a cool, very foggy day. The manor house, built originally by Gov. James Garrard, is surrounded by a grove on enormous, ancient blue ash and bur oak trees. The common practice at that time was to build manor houses in the middle of groves of old trees, creating
the instant appearance of an old English manor. Such is the case here – the trees are much older than the house. The blue ash trees are exceptionally large and tall – among the largest we have seen, though we will have to wait until another day to measure them. One blue ash is especially prominent because it appears never to have been struck by lightning and is very tall.
A nearby farm, also in the Clay family, has a number of ancient trees including a very fine bur oak standing in the middle of a pasture. Typical of most ancient bur oaks, it lost its top to lightning, but has built a vigorous new crown. This year, the old tree has a very large crop of acorns, and we plan to collect some for our nursery project.
Although our focus is usually on trees, one of the buildings on Runnymede farm caught our attention. Cooper’s Run Baptist Church was originally built in 1787, and completed in 1790. That original log structure was quickly outgrown, and the congregation built a new structure of cut limestone blocks beginning in 1801. Services were held in the limestone church from early 1803 to 1816, when the congregation needed a larger building. The church became part of the Gov. Garrard’s property and today is a barn at Runnymede. Brutus Clay likes to puzzle visitors by noting that the church was built in Virginia and only later found itself in Kentucky. Of course, the church didn’t move, the states did – in 1803, Bourbon County was part of Virginia.
There are several farms in the Bluegrass that are still operated by the original families that began farming them in the 18th or 19th centuries, and many of these farms have magnificent woodland pastures of venerable trees. It is the long-term land stewardship of the Clay family that has helped maintain the verdant landscape of the Bluegrass.
Lightning and Trees seem to go together. Many fires in the Western US are started by lightning strikes on trees. Here in the Bluegrass and Nashville Basin, we find fire scars on a very large number of trees. Lightning rarely kills our trees, but it is an important factor in their lives. Lightning-struck trees lose branches,part of their crown, sometimes the entire crown and have to rebuild. Decay becomes an important factor, but if the tree is healthy, growing well and stays ahead of the decay fungi, it will live a very long life.
We should never assume that a lightning-struck tree will decline or die, even if it appears severely damaged. Lightning struck trees are often over-managed by tree care workers eager to take action (and make a few bucks). Since lightning damage may take several years to fully reveal itself, observation is the best course. Obviously, this is not the case if the tree has an immediate target such as a home, street or playground. Even then, if possible, observation is best unless the risks are too great.
A street tree near my home was struck and lost some bark. A local tree company recommended that the tree be taken down, or that it be heavily pruned. The owner chose to do nothing and 30 years later, the tree is still in excellent shape. I have also seen trees that were struck, showed no damage and a year later were dead, probably because the roots were killed. Observation is the key.
The fate of a tree depends on the course that the lightning takes. During a thunderstorm, with water coursing down the bark, especially on smooth-barked trees like beech, the electricity may flow down the outside of the tree and do no harm (to the tree – anyone standing near it is at great risk). In drier condition, the current may travel through the wood, and either cause a crack or explosive rupturing of the wood. A cracked tree may not be seriously harmed, and again only time will tell. Old trees with significant decay are more likely to explode or be severely damage.
During the spring, the path of least resistance is the vascular cambium. The high salt and sugar content of the cambium and adjacent developing phloem and xylem provides a path for electricity. This may result in a strip of cambium being killed and the bark popping off, often in a spiral pattern. As with the cracked tree, damage may not be fatal. Sometimes the path boils the entire cambial layer, killing the tree. This may be immediately obvious if the bark pops off or explodes, or it can be subtle, with the tree dying some time later the same season or during the dormant season. I suspect that more trees are killed by lightning in the spring than summer, but this is difficult to prove, and there has been little research on the subject.
We find a certain number of very large old trees in the Bluegrass that die suddenly for no apparent reason – no signs of dieback, insects, diseases. I have long suspected that some of these trees have cryptic lightning damage, and that the cambium or fine roots were killed.
Fire is not a significant factor in the Bluegrass woodland pastures, though lightning-struck trees occasionally burn. We do not find fire scars in the wood, or charcoal in the soil. I have seen two blue ash trees struck by lightning that burned. Both were extensively decayed before the lightning strike and the fire traveled slowly down the interior of the stem. In neither case was a ground fire ignited, though there was grass scorched by the initial strike.
If we compare our woodland pastures with those of Europe, we can see a very different role of lightning. Lightning is much less common in most of Europe than it is here in the Bluegrass. It is probably a less important factor in the growth and development of European wood pastures than the woodland pastures of the Bluegrass. The maps below show the annual frequency of lightning strikes in the US and Europe (Data from NASA’s Lightning and Atmospheric Electricity Research at the Global Hydrology and Climate Center (GHCC). We do not know the frequency of lightning damage (e.g. stem scars) in European wood pastures compared with those in the US.