Tom Kimmerer
Scientist, Author, Conservation Photographer
  • Home
  • About
    • In the Media
    • Articles
  • Stories
  • Venerable Trees
    • Venerable Trees Book
    • Region
      • Geography
      • Cities & Counties
      • Geology
      • Soils
      • Land Cover and Forests
      • Historical Maps
      • Woodland Pastures
      • Woodland Pasture Photos
    • Trees
      • blue ash
      • bur oak
      • chinkapin oak
      • kingnut
      • Shumard oak
      • Range and Importance Value
  • Courses and Events
  • Photos
  • Tree Biology
  • Contact
Picture of E.O. Wilson

News News

Can we give up half of Earth to Nature?

Tom Kimmerer

February 14, 2021

Can We Give Up Half The Earth To Nature? Kentuckians Already Have.

The renowned biologist E.O. Wilson has proposed that we address the biodiversity challenge by giving up half the Earth to the natural world. In his 2016 book Half Earth – Our Planet’s Fight For Life, Wilson made a powerful case that humanity could afford to give half the Earth over to nature, while still allowing humans to thrive.  Many have challenged his proposition by saying that with a growing population and rising expectations of people in developing countries, we can’t give up any more land or water bodies to the natural world. Who is right? If we use Kentucky as an example, it is easy to see that Wilson is entirely correct.

Before we get to that, we need to discuss biodiversity. (For some definitions and background, see this article by Stuart Pimm).  There is a huge amount of gloom and doom surrounding a perceived biodiversity crisis. Some are calling this period the sixth extinction. Others say that insect populations are collapsing all over the world. There is a surfeit of end-of-the world ideation. We have been through this before. I vividly recall the end-of-the-world cries about the population bomb, initially promulgated by Paul Ehrlich, who has a consistent record of being wrong. Before the Clean Air Act and the Clean Water Act, we had predictions of the collapse of civilization due to pollution.

Some of these things could have come true, but we decided to fix them and we did. We humans, when we put our minds to it, are very good at fixing daunting problems. Whether it is climate change or the biodiversity challenge, we have been held back from making progress for the last four years, but now we are beginning to make rapid progress.

In an outstanding assessment by Emma Marris in The Atlantic, we can see the true status of biodiversity in the world now. Yes, too many species are threatened and endangered, and too much habitat has been lost, but we are not in the middle of a mass extinction. 902 species tracked by the International Union for the Conservation of Nature have become extinct since 1500. That is too many, but it is less than 0.7% of the species that IUCN tracks. Many more species are making extraordinary comebacks. Consider the wolf, American bison, or any number of other species that we have brought back from the brink of extinction. A small number of plant and animal species have seen population collapses – ash trees, chestnut trees, frogs, and others. Many more have seen population increases.

This is not to minimize the threats to many species. In Kentucky, in my lifetime, American chestnut, white and green ash, American elm, and Eastern hemlock have seen dramatic declines in populations due to insects and diseases that we introduced through careless import of contaminated horticultural products and untreated wood products. Yet none of these are extinct, and each of these trees has a dedicated groups of scientists, practitioners, and enthusiastic amateurs working to make sure they don’t disappear. With continued hard work, all of these trees will be brought back from the brink and will restore our forests.

What we need now is not only restoration efforts to bring these species back, but a massive effort to prevent more non-native insects and diseases from doing further harm. Many of us worry about invasive species, but the really important ones, economically and ecologically, are imported pests and pathogens, not plants. The economic and ecological impact of bush honeysuckle, considered a nemesis by many,  is trivial compared with the cost of the loss of white ash. And that loss could easily have been prevented if we had established tighter restrictions on the import of living plants and untreated wood products. Despite some improvements, our ability to prevent the next chestnut blight or emerald ash borer is too limited. 

Now back to the Half-Earth idea. The amount of forest land in Kentucky has increased from 20% in 1920 to 50% now, as farmers abandoned marginal lands and we became more urban. Deer, elk, beaver, otter, turkeys, bears, and coyotes have all returned, the first four with help from the Kentucky Division of Fish and Wildlife, the last two on their own. During the pandemic shutdown, I saw a beautiful coyote a couple of blocks from my downtown Lexington church, and a bear was recently seen wandering through the University of Kentucky campus. Kentucky is rewilding itself and this is good.

This rewilding is not without problem, such as the loss of trees mentioned earlier, but overall, Kentucky is a great example of why Professor Wilson is right. We can indeed allow the natural world to take over half of our state, and if we can do it, other places can as well. This is not to suggest that we simply walk away from that land, or lock it up. We need to dramatically improve the management of our natural resources to ensure that they remain healthy and productive. This management provides jobs, and allows continued use of these wild lands for multiple purposes, the famous 4 Ws of resource management: Wood, Water, Wildlife, and Recreation (say it out loud).

I am a realist, and understand that we have tremendous challenges, especially the climate crisis. So far, climate change is benefitting Kentucky with increased rainfall and longer growing seasons, but this may not continue. And we can’t forget that climate change is wreaking havoc throughout the world. But for Kentuckians, the natural world around us continues to thrive and provide us with immense benefits. 

So, the next time you hear people bad-mouth the Half Earth idea, tell them “Yeah, we Kentuckians are already doing it.”  And remember this as well: “There is no point in being pessimistic, it doesn’t work anyway.”

Picture of E.O. Wilson
E.O. Wilson, the renowned biologist who proposed the Half Earth idea
A picture of the books Half Earth - Our Planet's Fight for Life by E.O. Wilson
Half Earth, the 2016 book by E.O. Wilson
Emergence hole of emerald ash borer in a white ash tree
The characteristic D-shaped exit hole of an adult emerald ash borer, Agrilus planipennis after emergence from a white ash, Fraxinus americana.
Eastern hemlock trees killed by hemlock woolly adelgid
Hemlock trees, Tsuga canadensis, killed by hemlock woolly adelgid, Adelges tsugae
A picture of Kentucky forests in early spring
Kentucky’s diverse forests in early spring

Quercus macrocarpa-8111-Edit

News acorns, bees, News, oak, pollination, Tree Biology, Trees

Trees and Bees

Tom Kimmerer

April 21, 2020

Aecial spore horns of Gymnosporangium sp. on Amelanchier arborea

News apple, biology, cedar, cedar apple rust, News, pathology, Tree Biology

Rust Never Sleeps

Tom Kimmerer

June 7, 2018

Nature is often savagely beautiful, as when a leopard stalks a zebra. In the contest between fungi and plants, there are often such beautiful but savage moments. One of the showiest examples takes place in early summer, when spores burst out of cedar trees and soon attack apples, quinces, and serviceberries.

The players here are a rust fungus, cedar trees and trees in the Rose family.  Rust fungi lead marvelously complex lives. They infect one species of plant, produce spores and then infect a completely different plant. Without these two, often very different, hosts, the fungus is unable to complete its life cycle.

We begin our tale with cedar trees (Juniperus virginiana and other cedars). An infected cedar produces impressive, brightly colored,  gelatinous, horned structures in late spring. People often observe these – they are hard to miss – and are often concerned about harm to cedar trees. This is the time of year for alarmed posts on social media from people who want to know how to get rid of these odd structures. The answer is – don’t.  Cedar rusts are harmless to their host, and cause no lasting damage. 

It is a very different story for the other host, especially apples. When spores erupt from those beautiful spore horns on cedar, the float on the breeze, a few of them settling on leaves and branches of apple trees, as well as many other trees in the rose family, such as serviceberry.  There, the spores germinate, creating spots on leaves and fruit, often rendering the fruit inedible and unsalable.

While cedar-apple rust on apples can be treated with fungicide to reduce damage, a better alternative for farmers and home fruit growers is to select rust-resistant varieties. Fortunatey, many nurseries now offer rust-resistant apples and crabapples. For Kentucky growers, the College of Agriculture offers guidance. 

The story is, of course, more complex. First, there are many species of Gymnosporangium, including cedar-apple rust, cedar-hawthorn rust, cedar-quince rust, and others. Each has the same gymnosperm host, eastern redcedar (Juniperus virginiana), but different angiosperm hosts, including apples, quinces, serviceberry, hawthorn and others.

Next time you see these amazing colorful blobs on your cedar trees, enjoy them for their beauty and elegance. Then go buy some resistant apple trees.

Note: Some extension services recommend removing eastern redcedars near apple orchards. This is futile, in my opinion. Eastern redcedar is so abundant in Kentucky, and the spores so abundant and able to travel on the wind, that redcedar removal is not effective. Fungicide treatment is expensive and not completely effective. Fortunately, plant breeders have developed a number or resistant apple varieties. So, in Kentucky at least, enjoy your cedars and plant resistant apples.

Telial spore horns of cedar-apple rust

Telial spore horns of cedar-apple rust, Gymnosporangium juniperi-virginianae, on eastern redcedar.

Aecial spore horns of Gymnosporangium sp. on Amelanchier arborea

Aecial spore horns of Gymnosporangium sp. on serviceberry. Probably G. clavipes, cedar-quince rust.

cedar-apple rust on apple

Lesions caused by the aecial stage of cedar-apple rust, on crab apple.

cedar-apple rust on apple

Lesions on apple leaves caused by cedar-apple rust

Magnolia flower

News News, Tree Biology

Take a walk and smell the trees

Tom Kimmerer

May 29, 2018

One of the most interesting ways to experience trees is to take a “smell walk.” The next time you are walking in the woods or in your local park or cemetery, try to focus on the smells around you, especially if the day is warm and humid.  As you stroll along, pay careful attention to the constantly shifting palette of odors. The smell of pine and spruce may be obvious, but many tree flowers are broadcasting their presence by creating strong odors. Many trees are flowering right now, and most tree flowers have distinct smells. Hawthorns are almost sickeningly sweet, magnolias smell like my grandmother’s house. Often, it is difficult to find the tree making the strongest odors. While the giant flowers of  Southern magnolia are easy to find, the smell is fairly subtle. In contrast, the tiny flowers of American holly are easy to ignore, but their strong, sweet odor is hard to miss.

As you take your smell walk and observe trees in flower, notice the amazing diversity of insects swarming around the leaves and flowers. Many of these insects are attracted by very specific smells. You will see swarms of tiny flies around holly flowers, while various bees and beetles will be exploring the magnolia flowers. You don’t typically see honeybees, Apis mellifera, on most trees, although they seem to like yellow-poplar (tulip trees) flowers. Instead, you will see all manner of native insects that often specialize in a single tree species. 

Carefully watching a single flower comes with its own rewards. A large flower like magnolia may be visited by dozens of interesting creatures, from bees and beetles to spiders looking for an easy meal. 

My favorite place for a smell walk is Lexington Cemetery. Cemeteries often have a great diversity of trees, providing rewards for the smell walker. Today, on a muggy, warm day, I could smell rich floral scents from the moment I stepped out of my car. This cemetery is famous for its trees, and makes only scant use of flower beds, so most of the odors are from trees and shrubs. I started my walk assailed by a rich, sweet odor of holly trees, even though I could not see the flowers, which were high up in the canopy. By now, in late May, most of the early flowering trees like yellow-poplar and maples have finished flowering. Many buckeyes (Aesculus spp.) are flowering and are quite fragrant, though the related horsechestnuts don’t have much odor. Often, I will spend several minutes trying to track the source of a particular smell, sometimes to no avail. 

To have a rewarding smell walk, you don’t need to know the identity of the trees. Just keep your nose tuned to what is around you, and look for tree flowers. Then, take the time to observe the wonderful diversity of creatures visiting the flowers.

 

 

 

Magnolia flower

Southern magnolia, Magnolia grandiflora, flower

Carolina silverbell, Halesia carolina, flowers

American holly, Ilex opaca, flowers

maple flowers

Sugar maple, Acer saccharum, flowers

Book-Cover-348x500

News Bluegrass, News, Venerable Trees, Venerable Trees, Venerable Trees Book

A nice book review

Tom Kimmerer

January 12, 2018
Andrea Kornbluh of Rowan University has written a very thorough and kind review of Venerable Trees – History, Biology and Conservation in the Bluegrass in the Fall 2017 issue of Plant Science Bulletin. Here is her review:

[pdf-embedder url=”https://kimmerer.com/wp-content/uploads/2018/01/PSB-Book-Review-1.pdf” title=”PSB Book Review 1″]

[pdf-embedder url=”https://kimmerer.com/wp-content/uploads/2018/01/PSB-Book-Review-2.pdf” title=”PSB Book Review 2″]

The tree from Military Pike, during construction

News Bluegrass, bur oak, News, Trees

The Old Schoolhouse Oak

Tom Kimmerer

December 30, 2017

As we begin a new year working with ancient trees, we want to pay our respects to one of the most important ancient oak trees in Lexington. We were able to carefully preserve the tree during development, and today it is thriving. Here is a photographic tribute to the Old Schoolhouse Oak. I hope it has many more years, perhaps centuries, to look forward to. If you wish to visit the tree, here is a map.

[envira-gallery id=”4998″]

Christmas Trees-4184

News Christmas trees, News

Get a Real Christmas Tree

Tom Kimmerer

November 22, 2017
Think about the last time you were in a conifer forest – the smell, the wind softly stirring the canopy, the crunch of needles under foot. While you can’t precisely imitate  a forest in your living room, bringing a live Christmas tree into your house comes pretty close. We know that people benefit greatly from being among trees. Numerous studies show that walking through a forest confers tremendous psychological benefits. In Japan, the practice of Shinrin-yoku, or Forest Bathing, is thought to confer important health benefits. Forest bathing simply means walking through a forest in a calm manner. Walking through a park or along a shady street has many of the same effects. The benefits of being near trees are legion.

Bringing a fresh-cut live tree into your living room at Christmas may have many of the same benefits. The smell of a real fir tree, the calming color, and the presence of something living in your house may be one of the most pleasant aspects of the holidays.

Why, then, do so many of us choose artificial trees? There has been a steady decline in the number of households with live trees in the United States. Today, more than half of homes use artifical trees.  The main reason seems to be convenience. Real trees are a bit messy, from the sticky sap to the needles that drop over the course of the Christmas holidays.

There are other benefits of real trees. Most real Christmas trees are grown on farms and support many farm families. Although Christmas tree farms do use pesticides and herbicides, the amounts are low compared with conventional crops. In the mountains of North Carolina, Christmas tree farms support over 1500 farmers and many more laborers in a sustainable agricultural ecosystem.  Most of these farms are on steep slopes, land unsuitable for other crops.

The life of a real Christmas tree is not over after the holidays. Most cities now recycle Christmas trees into mulch. In Kentucky, the Department of Fish and Wildlife is using Christmas trees dropped into lakes to improve fish habitat. If you have room in your backyard, leaving your tree out for the winter provides cover for song birds (and food if you add garlands of cranberries and popcorn).

What about live balled-and-burlapped trees? These are best left outside. Bringing a live dormant tree into a warm, dry environment, then taking it back outside into the winter cold is very stressful. These trees often do not survive.

Good quality trees are available in many locations. Trees at big box stores are often harvested months before they are available for sale, and are often too dry to survive the Christmas season in your house without dropping large numbers of needles. Local vendors often get fresher trees. In Lexington, Kentucky, where I live, the very fresh Fraser and concolor (white) firs at Hillenmeyer Christmas Shop are very fresh and should last through the Christmas season in your home.

If you want to save some money, less expensive trees are often available at choose-and-cut farms. And, if you want a free tree, albeit with some driving and manual labor, most US National Forests will allow you to find trees out in the woods, cut them, and take them home.

Fraser fir and concolor (white) fir at Hillenmeyer Christmas Shop.

Christmas trees ready for sale

Christmas trees, ready for sale

Fraser fir, Abies fraseri, Christmas tree

Fraser fir, Abies fraseri, Christmas tree

Concolor fir, Abies concolor, Christmas tree, also known as white fir.

Concolor fir, Abies concolor, Christmas tree (also called white fir)

Graph

News Bluegrass, climate change, News, tree growth

The longest growing season – Updated

Tom Kimmerer

November 3, 2017

UPDATE: A sudden cold front ended the growing season (at least in Kentucky) on the morning of November 11. This story has been updated to reflect the changed growing season length. We came close, by two days, from setting an all-time record. This year is the second-longest growing season on record.

In much of the eastern US, gardens are still growing, late fall flowers are still blooming, and trees are only reluctantly and slowly changing colors. It is still the growing season. There are various ways of defining the growing season, but for plants, a temperature of 28 F for several hours is considered a killing frost. Plants that have not prepared for winter by entering dormancy will be damaged at this temperature.

For Lexington, Kentucky, the US Weather Service provides the following dates from long-term records, using the 28 F measure.

Latest first fall hard freeze (28°):  December 4, 1899
Longest growing season:  242 days in 1922

For 2017, the numbers are:

First fall hard freeze (28 F):  November 11
Growing Season Length as of November 11:  241 days

The last hard freeze was March 16, when the temperature reahed a low of 18 F. There has not been a hard freeze since, although a few nights flirted with 32 F and there was patchy frost. The current short term weather forecast shows little chance of a hard frost in the next two weeks. The current long-term weather forecast tells us that we are unlikely to see below-freezing temperatures before December 12 (though long-range forecasts are not very reliable). As it happens, the long-range forecast is still for warm weather, but the trend was abruptly ended by a hard freeze in the early morning of November 11.

While this may be good for gardeners and farmers, there are negative consequences. Many natural processes, such as flowering and plant growth, hibernation and emergence of animals, are tied to careful measurement of temperatures. A very short and warm winter may prevent some plants from beginning growth at the right time in spring. Bird migration is profoundly affected, because migration north is cued by daylength, at least in some birds. In a warm and early spring, emergence of caterpillars and other insects that provide food for foraging birds may occur before the birds are on the move, leaving the migrants with too little food.

Growing seasons throughout the US have been getting longer since 1980, a clear result of a warming world. Throughout the US, growing seasons are now an average of 15 days longer than they were prior to 1980, with more northerly states experiencing up to 30 days’ longer growing season.

Graph
Frost free seasons in the continental United States.
sassafras

Sassafras in autumn

Kentucky Horse Park

Photo by Erin Barnhill

News Bluegrass, Classes and Workshops, field course, News, Venerable Trees

Venerable Trees Field Course

Tom Kimmerer

October 26, 2017

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.

[envira-gallery id=”4886″]

Emerald ash borer

News ash, emerald ash borer, extinction, News

Extinction Before Our Eyes

Tom Kimmerer

October 24, 2017

We rarely see plants or animals become extinct before our eyes. Extinction is often something far away and abstract – it happened long ago or far away. Yet right now before our eyes, one of the most important groups of trees is vanishing. Ash trees, in the genus Fraxinus, are rapidly disappearing, and there is little we can do to prevent it.

The extinction of plants and animals happens all the time, but it is usually a remote event that we read about in the news or in biology texts. The dodo, black rhino, passenger pigeon and many other animals and plants have become extinct in historical time. Often, these have been rare species, or species uniquely susceptible to the invasion of humans. In her important book The Sixth Extinction, Elizabeth Kolbert has argued convincingly that we are on the brink of, or have already begun, the sixth major extinction event in Earth’s history, with the potential loss of thousands of species.

Animals, especially charismatic mammals, get most of the attention, but the number of tree species that have recently become extinct, or are on the brink of extinction, is large and growing. Many of these trees are rare or have very small populations or ranges, and are threatened by habitat loss. Maple-leaf oak, Quercus acerifolia, is only found in a few stands in the Ouachita Mountains in Arkansas, with fewer than 600 individual trees. Destruction of its forest by fire, logging or other disturbance could eliminate this species in the wild. 

The current crisis for ash trees is ompletely different. Ash trees are dominant components of North American forests, and are commercially important for timber and as ornamentals. In a period of less than 30 years, ash trees have gone from thriving and beautiful components of our native forests and planted landscapes to arriving on the brink of extinction. The IUCN Red List of threatened and endangered species has recently added almost all North American ash trees to the categories of Critically Endangered or Endangered. Critically endangered species are those on the brink of extinction, while endangered species are only slightly less liable to become extinct. Populations of all these species are rapidly declining.

Status of North American ash trees in the IUCN Red List:

Name Name Red List status Population trend
Fraxinus americana White Ash Critically Endangered decreasing
Fraxinus caroliniana Carolina Ash Endangered decreasing
Fraxinus nigra Black Ash Critically Endangered decreasing
Fraxinus pennsylvanica Green Ash Critically Endangered decreasing
Fraxinus profunda Pumpkin Ash Critically Endangered decreasing
Fraxinus quadrangulata Blue Ash Critically Endangered decreasing

Most people are aware of the cause of this impending extinction: the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera:Buprestidae), a tiny and beautiful beetle, emerald green as its name implies. The insect was introduced in the Port of Detroit or the Port of Windsor around 1990. The beetles were in wood packing crates used to contain heavy machinery, and shipped from China. The beetle is native to much of China, but in its native range, it only attacks and kills stressed trees. North American ash trees (with a possible exception, see below) are susceptible to beetle attack even when they are healthy. The female deposits eggs on the bark surface, and her larvae burrow into the tree, feeding in a serpentine gallery and destroying the cambium and phloem. The tree dies from the top down, sometimes taking several years to die. Once a tree is infested, its death is inevitable.

We are now facing an extinction event almost as great as the loss of the American chestnut. Ash trees have gone from being among our most important species, both ecologically and commercially, to the edge of extinction in less than 30 years.  Despite this huge event, news coverage of this extinction tends to be local and focus on tree loss in a community or region. 

North America is under a constant barrage of introduced pests, pathogens, and invasive species. Most introduced species do not become a serious problem, but the few that do can be devastating. We are witnessing not only the impending extinction of several tree species, we are also seeing a simplification of our forests, as the abundance of many common trees declines. The US, Canada, and Mexico have vigorous inspection programs to prevent the introduction of new pests and pathogens into our ports, but it is not sufficient. About 10 new beetle species are found around ports of entry every year. For beetles like emerald ash borer that hitchhike on wood packing material, the solution is fairly simple – forbid the use of solid wood packing material, and instead use reconstituted products like particleboard. The manufacture of reconstituted products requires grinding of wood, heating, and the use of adhesives; beetles do not survive this process.

What will be the fate of ash trees? I think is is unlikely that ash will become extinct. I have been unable to find accounts of any plant species driven to extinction by an insect. It is possible, even probable, that there are small numbers of trees in each ash species that are resistant to emerald ash borer – this is the essence of evolution by natural selection. If so, these survivors will be able to create future populations of ash. This process will take hundreds or thousands of years, but we can accelerate the process by selecting for and propagating resistant ash. Blue ash may be a special case: it appears that healthy, unstressed blue ash trees are resistant to emerald ash borer. 

We need not wait for natural selection, a slow process, to create new populations of resistant ash trees. Artificial selection for resistance is already showing promise. Justin Whitehill and other scientsts have found that ssh trees that have high concentrations of a natural insecticide, verbascocide, show some resistance to EAB. As more scientists pursue this problem (and if required funding is provided), EAB-resistant populations of ash species my be created by a combination of traditional selection-and-breeding and molecular methods such as CRISPR/CAS9. The loss of ash trees is a problem we created, and we need to fix it.

 

Dead ash trees

Young white ash trees killed by emerald ash borer. Some lower branches are still alive

dead white ash

Mature white ash in Lexington Cemetery, killed in one season by emerald ash borer

Emerald ash borer larval tracks

Stem of an ash killed by emerald ash borer, showing the characteristic s-shaped track from the larvae eating cambium and phloem

Emerald ash borer

Adult female emerald ash borer feeding on an ash leaf

Chinkapin oak

News Lexington, News, Trees, Urban forestry, Venerable Trees, Venerable Trees

Here are a few of my favorite trees

Tom Kimmerer

August 31, 2017

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. 

[envira-gallery id=”4837″]

Oak leaf

News autumn, leaves, News, Tree Biology, tree biology

Leaves Are Wearing Out

Tom Kimmerer

August 29, 2017

Have a look at the leaves of trees around you. Chances are pretty good that they don’t look healthy. Fading leaves with holes and other insect signs, mold and other fungi and a generally bedraggled look are normal at this time of year.  What is wrong with the tree? Probably nothing.

Leaves look bad at this time of year for one reason: they are disposable.  Leaves are the botanical equivalent of Kleenex – made to be used for a short time and then thrown away. As a result, trees have a limited ability to repair leaves, and the injuries from weather, pests, and pathogens continue to accumulate through the growing season.

These sad-looking leaves are actually the beginning of a complex series of steps that trees take to get ready for winter. The most important process in getting ready for autumn is for the tree to withdraw critical nutrients into the stem or roots. For a tree to toss away leaves rich in protein and other forms of nitrogen is a waste of resources. While the bugs  chew and the fungi grow, trees are busy pumping all the important nutrients out of the leaves and into the stem and roots. These changes are subtle at first, but will soon be visible as autumn colors begin to develop. 

This is not to say the trees are free of disease. Many serious problems, especially wilt diseases, show themselves at this time of year. These diseases are often fatal, though usually slowly. It sometimes takes a degree of expertise to figure out whether sick-looking leaves are benign or signs of a serious problem. Wilt diseases that limit the access of leaves to water are usually fatal and largely untreatable. Sometimes, the services of a plant disease diagnostic lab are needed to figure out whether a tree is truly sick.

Close observation of trees at this time of year can be rewarding. The development of autumn colors often starts very early. Some trees, such as walnut and hackberry, have already begun dropping leaves and turning yellow. 

Oak leaf

Insect and fungal damage on Shumard oak leaf

 

Sweetgum leaf

Sweetgum leaf with fungal and insect damage

Photo by Flickr user Torbakhopper

News canopy gaps, eclipse, News, Trees

Trees in the Eclipse

Tom Kimmerer

August 17, 2017

The total eclipse of August 21 is rightfully attracting huge attention. Towns along the totality band will be flooded with people anxious to experience this rare event. Most of us, wearing our eclipse-safe glasses, will be looking upward to watch the complex but short-lived changes in the sun as the moon passes over.  But you should consider getting close to some trees and looking down. As the sun filters through a tree canopy, the little gaps between the leaves act like thousands of pinhole cameras. The result is what you see in the picture to the right.

As the moon crosses the sun, you will see crescent-shaped spots on the ground or on nearby walls. If the day is breezy, these crescents will dance across the landscape, creating a magic effect. As the eclipse approaches totality, the crescents will become smaller and overlap less. During totality there will be no crescents but they will quickly reappear.

The good thing about watching the sun crescents on the ground is that it is entirely safe as long as you don’t stare up into the canopy. At the moment of totality, when the sun goes completely dark and the dapples disappear, it is safe to look up for a minute. This provides a convenient and safe alternative to making pinholes on cardboard or other ways of viewing the eclipse.

It may be tempting to photograph the eclipse itself, but there is almost no way you can duplicate the work of the many thousands of professional photographers who will be out there.  You can, however, get great and unique photos of the sun dapples on the ground. So, give it a try. And at the moment of totality, put your cell phone away and just enjoy the splendor of a total eclipse.

Be safe, follow the rules, and happy eclipsing!

Photo by Flickr user Torbakhopper

Photo by Flickr user Torbakhopper

Veterans Park Oak-4895-Edit-Edit

Bluegrass, bur oak, Classes and Workshops, Great trees, Lexington

Lexington’s amazing trees

Tom Kimmerer

August 14, 2017

I have lived in and near Lexington for about 35 years. As a careful observer of trees, I have always been amazed at the number of very large trees. This became the subject of my first book, Venerable Trees – History, Biology and Conservation in the Bluegrass.  Since 2005, we have been working with landowners and others to conserve our ancient trees and to provide opportunities for them to successfully reproduce.  As part of that work, we have been using GPS and GIS to map and record the condition of as many trees as possible. 

Sadly, the population of big, old trees in our community is continuing to decline. While construction, lightning, age and disease are major causes of their decline, I think there is a more fundamental problem:  we do not sufficiently value our great trees to ensure their survival.

We are planning a walking and bus tour of some of the Great Trees of Lexington in an effort to bring more attention to their plight, and to create a community-wide effort to do more to preserve our natural heritage. The tour is scheduled for Saturday, September 16 from 8:30 am to 1 pm.  We will begin our exploration at West 6th Brewing, travel by bus to as many sites as time allows, and return to West 6th for an informal discussion of ancient tree conservation.  Each participant will receive a map of known large trees in Lexington.

Attendance is limited to 30 people. We hope you will join us.  Register here and we will send you more information.

Map of trees
Great Trees of Lexington

Carya glabra-7485-Edit

News News, senses, tree physiolog, Trees

The Sensory World of Trees

Tom Kimmerer

March 31, 2017

Spring is the time when trees compel our attention. With buds opening, leaves growing, flowers emerging, trees seem to call out to us, even if we ignored them all winter. Trees have also been very much in the news in the last few years for three main reasons: 1) the continued loss of forests in some regions; 2) the importance of trees and forests in addressing climate change; and 3) new understanding of the way trees sense their world and communicate with other organisms.  Interest in the latter has been propelled by the book The Hidden Life of Trees and media coverage of the work of several scientists, notably Suzanne Simard at the University of British Columbia.  At Venerable Trees, we are beginning to offer workshops in the the sensory world of trees, under the title What Do Trees Know?

As you enjoy your sensory experiences with trees this spring, spend a moment to think about the sensory experiences of those trees.  Although trees have many of the senses that we do, and some we don’t, the sensory organs and mechanisms are different. Trees can smell other trees and other organisms, for example, even though they lack a nose. 

Here are some things that trees can do that you may not know about. 

  • Smelling/tasting
  • Hearing
  • Feeling (touch, not emotions)
  • Seeing – trees have an exquisite sense of vision through photoreceptors; they can see wavelengths that we can’t, including infrared and ultraviolet; they can detect subtle and sudden changes in light energyenergy that we don’t notice; and they can  respond to individual photons.
  • Measuring – trees are constantly monitoring and measuring their environment, they can measure:
    • Time to milliseconds;
    • Light direction, shadows;
    • Gravity direction, intensity;
    • Magnetic fields;

This is by no means an exhaustive list of the sensory world of trees. On June 23, we will explore the sensory world of trees and lots of other things in our next Field Course at West Sixth Farm in Frankfort.   We will take a detailed, but not technical, look at the lives of trees from their perspective.  We hope to see you there!


Shumard oak leaves in rain

Photo by Katherine Williams Shaw

News blue ash, emerald ash borer, News, Trees, Venerable Trees

Blue Ash and the Emerald Ash Borer

Tom Kimmerer

March 2, 2017

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. 

 

Photo by Katherine Williams Shaw

D-shaped exit holes in blue ash. Photo by Katherine Williams Shaw

Photo by Katherine Williams Shaw

Galleries formed by emerald ash borer larvae. Photo by Katherine Williams Shaw

Chinkapin oak

News chinkapin oak, Classes and Workshops, field course, Griffith Woods, Katherine Williams Shaw, News

The Three Sisters

Tom Kimmerer

February 14, 2017

The Three Sisters

Griffith Woods Wildlife Management Area is a magical place of huge, ancient trees. Some of our favorites are the chinkapin oaks that we call the Three Sisters. Katherine Shaw took this nice picture of the Three Sisters. These are very large, very old trees. However, unlike the kingnut trees that surround them, these chinkapin oaks do not appear to be reproducing. At our upcoming Field Course on March 4, we will take a very close look at these wonderful trees and search for their progeny. Lack of reliable reproduction is a major cause of the decline of our ancient trees and woodland pastures. 

Chinkapin oak

The Three Sisters at Griffith Woods Wildlife Management Area. Photo by Katherine Williams Shaw

Black Vultures KWS-3974

News black vulture, Coragyps atratus, News

Black Vultures in Trees

Tom Kimmerer

February 8, 2017

Vultures are a daily site throughout the Bluegrass. The majority are turkey vultures, but in recent years there has been a gradual increase in the population of black vultures, Coragyps atratus. This is significant because, while turkey vultures are strictly scavengers, black vultures are both scavengers and predators. Although tales of them attacking grown livestock are certainly apocryphal, there is no question that they will pray on newborn calves and foals. On balance, though, their role as scavengers is economically more important than their occasional predation. If not for vultures, our roadsides would be deep in animal corpses.

While driving along Owenton Road in Minorville, Katherine and I chanced upon an oak tree hanging over the road with a large flock of black vultures enjoying the sunshine. Here is a gallery of photos of these beautiful birds. All photos by Katherine Williams Shaw.

Bur oak

News bur oak, drone, News, Photography

Flying Over a Bur Oak

Tom Kimmerer

February 2, 2017
Today, the Venerable Trees staff worked with Beard House Media to get our first drone inspection of a huge bur oak.  It is very difficult to estimate the volume of a big tree, or to inspect it for potential problems.  Aerial or satellite photos often lack detail.  Today, our friend Jeremiah Oschwald from Beard House Media flew his Phantom 4 Quadcopter over the big bur oak at the Peninsula on Squires Road. This cite has been approved for development, but we are protecting this magnificent bur oak and the surrounding trees.

We plan to begin using drones to carefully inspect large trees and also to begin creating 3D models of trees. One of our goals is to be able to estimate the amount of carbon stored in the huge trees. Large trees are very important for carbon sequestration, one of the solutions to the problem of climate change.  We will tell you more about this soon.

For now, we hope you enjoy this wonderful aerial photo of this huge tree.  Scroll down for more information about our drone use.

Bur oak
Drone photo of a bur oak. Photo by Jeremiah Oschwald

Small drones have become much more useful as more automation is built into them.  The Phantom 4 drone used by Beard House Media is capable of autonomous flight. Jeremiah programmed a grid into the drone’s software. Once it took off, it flew directly to the grid, pausing at set locations along the grid to take a photo. The photo here is stitched together from multiple drone photos.

This video clip shows the drone hovering over the big bur oak, then moving and pausing again.

Aerial photo

News History, News, Venerable Trees, woodland pastures

Losing woodland pastures

Tom Kimmerer

January 31, 2017

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.

Aerial photo

The future site of Fayette Mall, 1967 photo. The yellow arrow shows the Tiverton Oak, the only remaining tree of the original woodland pasture. Source:

 

Bur oak

The Tiverton Oak

Coldstream-8165-Edit

News Classes and Workshops, development, field course, News, Urban, Venerable Trees

Ancient Trees at the Urban Boundary

Tom Kimmerer

January 26, 2017

 

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 info@venerabletrees.org, 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 Coldstream Complex

Persimmon fruit

News gender, News, persimmon, Tree Biology, Trees

Gender identity and the mystery of the persimmon fruit

Tom Kimmerer

October 17, 2016

Persimmon fruit

What does gender mean? We know that human gender is a broad and fluid landscape within which people choose to identify themselves. This is increasingly recognized as a healthy and welcoming way to think about who we are. Gender fluidity is true in many animal species, perhaps the majority.  But what about plants?

The photograph above is a mystery. Not its identity. It is a persimmon fruit lying on a driveway in Castlewood Park, Lexington. The mystery is the tree next to it. This is the only persimmon in the Park. I have known this tree for over 25 years and see it regularly, at least once a year. The mystery is that this is the only fruit this tree has ever produced, to my knowledge. And therein is the the tale of gender fluidity in a tree.

Persimmon, Diospyros virginiana, is a gorgeous tree with very distinctive bark. It is an important component of many forests from river bottoms to rocky hill slopes. In the Bluegrass, it is often found on farm hedgerows and the edge of woodlots. Persimmon is closely related to ebony (Diospyros ebenum and related species), the tree with dark brown or black wood famous for making the black keys on a piano, the pegs and fingerboard on violins, and fine clarinets.  The heartwood of persimmon is also very dark, but most trees have only a little heartwood with a much paler sapwood. Persimmon was prized for making golf clubs known as “woods”, though today only a few artisans still make authentic persimmon clubs.

So why is this fruit so strange? As with humans, tree species often lie upon a spectrum of genders. This solitary fruit brings us to ask “what is the sex of this tree?”  Many trees are monoecious, with male and female reproductive organs in the same individual tree. Others are dioecious, with male trees and female trees. A large number of trees lie somewhere in the middle. Some trees are mostly male with a few female flowers. Others are the reverse. Botanists have made up dozens of words to describe various expressions of sex, such as polygamodioecious (mostly one sex, some flowers of another), subgynoecious (mostly female with a few male or bisexual flowers). Charles Darwin devoted much of his career to the forms of sexual expression in plants, writing three books on the subject and recognizing dozens of different patterns of sexual expression.

For twenty five years, I have thought that this tree is male. Persimmon is one of the most strongly dioecious tree species in our flora. Trees are either male or female. Period. Yet here is a tree that has either been male the whole time I have known it, or has been asexual.  Scan as we might, my friend and I could not see another fruit in the tree or on the ground. Is this tree in transition from male to female, and will make more fruits in subsequent years?  Did one branch or one flower suddenly decide to be female for just a single occasion? We don’t know, but this single fruit certainly compels us to keep an eye on the tree and await further developments.

Gender identity in higher organisms is complicated, subject to evolutionary pressures that we barely understand. Gender identity in trees is complicated, difficult to understand, and fluid. Why should it be any different in humans? It shouldn’t.

Persimmon tree

A persimmon, Diospyros virginiana, in Castlewood Park, Lexington

Stem of persimmon tree

Stem of persimmon tree in Castlewood Park

Bur oak, Quercus macrocarpa, at St. Joseph Medical Center parking garage.

News Bluegrass, Classes and Workshops, News, Urban forestry, Venerable Trees, Woodland pasture

Rethinking Urban Forestry in Lexington

Tom Kimmerer

August 8, 2016

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.

Bur oak, Quercus macrocarpa, at St. Joseph Medical Center parking garage. Castlewood-9253-Edit Blue ash in Ecton Park, Lexington

Veterans Park Oak-4895-Edit-Edit

News Ancient Trees, Fayette County, field course, News, Venerable Trees, woodland pastures

Field Course – Ancient Trees of Fayette County

Tom Kimmerer

July 19, 2016

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.


Registration Fee



Veterans Park Oak-4895-Edit-Edit

Gosnold on Cuttyhunk

News exploration, Gosnold, News, Pring, sassafras

America’s First Export

Tom Kimmerer

July 12, 2016

In 1602, Captain Bartholemew Gosnold set sail from Falmouth, England on the barque Concord, making land on the Maine coast and searching southward along the coast to the island of Cuttyhunk, Massachusetts. A year later, Captain Martin Pring set out on a similar voyage aboard the pinnace Speedwell, sailing down the Maine and Massachusetts coast to Martha’s Vineyard.

Pring took note of “tall okes, beeches, pine trees, firre trees, hasels, witchhasels and maples,” but cared little for them. Neither Gosnold nor Pring took special note of the tall white pines that were to be the mainstay of the American economy in decades to come.  Both captains were in search of the most precious commodity American had to offer: sassafras.

The crews of both ships remained on shore for several months. Gosnold intended to leave some of the crew behind as settlers, but the chosen crew members declined to stay and their nascent village was abandoned. Both captains returned to England with salt cod, beaver fur and other novelties, but the the holds of the ships were mostly filled with sassafras roots.

What was so important about sassafras?  This is what Captain Pring said of sassafras: “a plant of sovereign virtue for the French Pox, and as some of late have learnedly written, good against the Plague and many other Maladies.”  The French Pox is what we now call syphilis.

In 1577, the Spanish physician Nicolas Menardes had written an influential book, translated into English as “Joyfull Newes Out of the Newe Founde World.” Menardes extolled the medicinal virtues of many plants, but especially sassafras. Menardes regarded sassafras as useful for ‘the griefes of the Stomache’, ‘the griefes of the stone, ‘the evill of the Mother and windiness’ and ‘pestilent and corrupt airs.”

Menardes provided a recipe for making strong tea from sassafras roots. Here is his recipe, which should be familiar to anyone who has made sassafras tea. “They took up by the roote of this Tree, and tooke a peece thereof, such as it seemed to them beste, thei cutte it small into verie thinne, and the little peeces, and cast them into water, at discretion, that whiche thei saw was needefull, little more or less, and thei sodde it the tyme that was needfull, little more or less, and thei sodde it the tyme that was needefull, for to remaine of good coulour and so thei dranke it, in the morning fastyng, and in the daie tyme, and at dinner and supper.”

Menardes’ book created demand for sassafras roots, especially as syphilis rampaged through the upper classes and aristocracy of Europe. Gosnold raised money to buy his ship and set sail. Pring was sent by Sir Walter Raleigh. Although both sailors spent time exploring the American coast, and Gosnold attempted to establish a colony, it was sassafras root that paid for their voyages. Because of these voyages, sassafras became America’s first cash crop.

Both Gosnold and Pring went on to distinguished careers as explorers and settlers. But their first job as explorers was to dig up sassafras roots.

Sources:
Archers relation of Gosnold’s Voyage, Mass. Hist. Coll 3d series, vol 8
Hakluyt, Richard. 1906. Early English and French Voyages: Chiefly from Hakluyt, 1534-1608. C. Scribner’s Sons.
Monardes, Nicolás. 1925. Joyfull Newes Out of the Newe Founde Worlde. Constable & Company, Limited.
Pring, Magazine of American History V. 8

Painting by Bierstadt

Gosnold on Cuttyhunk, 1602 by Albert Bierstadt, Oil on Canvas 1858

sassafras

Young sassafras leaves, Sassafras albidum

sassafras

Sassafras in autumn

sassafras flower

Sassafras flowers, Sassafra albidum

1 2 3 4 ›»
Back to Top
Tom Kimmerer