Leader of Today’s Ramble: John Schelhas
Authors of Today’s Report: John Schelhas, Don Hunter
The photos that appear in this report were taken by Don Hunter unless otherwise credited. Photos may be enlarged by clicking them with a mouse or tapping on your screen. Not all of Don’s photos from today’s ramble made it into the Ramble Report, so be sure to check out his Facebook album at this link .
Nature Ramble Rainy Day Policy: We show up at 9:00 a.m., rain or shine. If it’s raining, we will meet and socialize in the conservatory (bring your own coffee); if there is a break in the rain, we’ll go outside and do a little rambling.
Today’s Emphasis: Tree microhabitats
Announcements and other interesting things:
Roger Nielsen announced that the Oconee River Land Trust is hosting a hike and happy hour, with hors d’ oeuvres, beer, and wine, on Saturday, November 2, from 2:00 pm – 5:00 pm. It will happen at Walt Cook’s conservation easement on the Middle Oconee River.
Speaking of microhabitats: Mountain Plants Host Unique Microscopic Communities
Today’s Reading: John read a paragraph from the essay, “Conservation” from Round River: From the Journals of Aldo Leopold.
“The outstanding scientific discovery of the twentieth century is not television or radio, but rather the complexity of the land organism. Only those who know the most about it can appreciate how little we know about it. The last word in ignorance is the man who says of an animal or plant: “What good is it?” If the land mechanism as a whole is good, then every part is good, whether we understand it or not. If the biota, in the course of aeons, has built something we like but do not understand, then who but a fool would discard seemingly useless parts? To keep every cog and wheel is the first precaution of intelligent tinkering.” Aldo Leopold, "Conservation," Round River: From the Journals of Aldo Leopold.
Tree Microhabitats
“Tree microhabitats” is a new term for a category that came out of European forest research. It brings together things we already know, but establishing the category helps group them and understand their importance. Microhabitats refer to small habitats that are on trees (not places on the ground where different trees are found), such as a limb or twig, or perhaps a hollow or decaying knot hole filled with soil or containing water. Maybe it’s a rivulet of sap, dripping from a woodpecker hole or from a fissure caused by a lightning strike, attracting ants, which attract birds. Maybe it’s a leaf, hosting a wasp gall. It might be a tangle of limbs and leaves, providing a safe haven from predators for a variety of small species of insects or other critters. It could be a bird’s nest. The important thing to know is that these microhabitats are all structural things. You don’t really have to know the species of the trees – or the insects or the fungi, etc. that live there – to appreciate the concept and look for tree microhabitats. Just being able to recognize the different microhabitats can get you thinking about all of the connections found within a forest and can help you see some of “the cogs and wheels” of forest ecosystems.
Illustration from Martin et al. 2022. Tree-Related Microhabitats Are Promising Yet Underused Tools for Biodiversity and Nature Conservation: A Systematic Review for International Perspectives. Frontiers in Forests and Global Change, Vol. 5: 818474.
European researchers have developed a catalogue of different tree microhabitats that offers an accessible classification system for identifying small and valuable structures for biodiversity. The Catalogue was developed by a group of experts at the European Forest Institute to serve as a field guide. The vast array of existing tree microhabitats (TreMs) is subdivided into a few concise categories of saproxylic (cavities, injuries and wounds, bark, dead wood) and epixylic (deformations, epiphytes, nests) structures that can serve as shelter or home for different flora and fauna.
Left, decayed hole at the base of a hickory tree has an accumulation of soil-like wood at the bottom. Right, a patch of moss on a Beech trunk is an epiphyte that provides cover for small insects.
While there is a lot of forest ecology and silvicultural science behind the categories, the Catalogue can be used simply as a field guide and handy support for determining valuable microhabitats during forest management. In addition to being available in pdf form, there is also an “Integrate+tree microhabitat” phone app for identifying biodiversity-relevant tree microhabitats. The app content has been taken from the publication Catalogue of tree microhabitats – Reference field list and is available in several languages. The I+TreMs catalogue is available as a free app, running on Android and Apple.
Tree microhabitat resources:
Kraus, D., Bütler, R., Krumm, F., Lachat, T., Larrieu, L., Mergner, U., Paillet, Y., Rydkvist, T., Schuck, A., and Winter, S., 2016. Catalogue of tree microhabitats – Reference field list.
Integrate+ Technical Paper. 16p.
Bütler, R.; Lachat, T.; Krumm, F.; Kraus, D.; Larrieu, l. 2020. Field Guide to Tree-related Microhabitats: Descriptions and size limits for their inventory. Birmensdorf, Swiss Federal Institute for Forest, Snow and Landscape Research WSL. 59 p.
Old growth Tulip Tree in Cooper’s Creek Recreation Area in the Chattahoochee National Forest. Old growth trees have many more microhabitats than younger trees. Photo by Georgia Forestwatch
In general, research has shown that the more tree microhabitats you have in a forest, the greater the diversity of organisms in that forest. As you might expect, natural forests have more tree microhabitats in them than plantation forests, which are generally, as a part of their management, kept “cleaned up” by removing deadwood and fungi, keeping fallen limbs picked up, keeping shrubs thinned out, etc. Additionally, old growth forests have many more tree microhabitats than younger forests, as you can see looking at almost any large, old tree or visiting an old growth forest such as the Tulip Trees in the Cooper’s Creek Recreation Area in the Chattahoochee National Forest near Suches, Georgia. Importantly for forest management, you can enhance tree microhabitats in a plantation forest by leaving diverse tree microhabitats, such as deadwood, cavities, and fungi, or by leaving one or more large trees. Having more microhabitats and diversity in a forest in general will increase the resilience of a forest and perhaps even its productivity as trees often grow better in complex natural-like ecosystems rather than in simple ones focused on producing wood fiber.
Today’s Route: We left the Children’s Garden, and, via the entrance road, made our way to the White Trail and headed across the powerline ROW to the turkey-foot intersection of the Blue, Green, and White trails. We stayed within sight of the intersection, checking out various trees for microhabitats.
Today’s Observations:
John led the ramblers to the junction of the Blue, Green, and White Trails just west of the powerline right-of-way. Here he handed out forms for recording different tree microhabitats. As examples of things to look for, John mentioned that he had seen, in a reconnaissance for today’s Ramble, a dead branch up in one of the trees, the loose bark of White Oaks that provides shelter for insects (and even small bats), and Hook Moss providing cover for small insects avoiding predation by woodpeckers and other birds. John sent us out in small groups to check out different trees in the vicinity to find and identify microhabitats. We regrouped after 30 or 40 minutes to see what the different groups found.
Loose plates of White Oak bark (left) and Hook Moss on a Hop Hornbeam (right)
provide shelter for insects.
Don noted fresh sap oozing from a Northern Red Oak’s bark, potentially attracting insects and birds.
Page spied a twig supporting a row of Little Nest Polypore fungi.
Gary spotted a deep, damp hole at the base of a tree with a large mushroom growing in the bottom.
Linda’s group discovered a Beech tree with a cascade of reddish liquid down the trunk; it appeared to originate about 15 feet above the ground, perhaps in a large knot hole.
The base of the Beech tree is buttressed, the spreading roots creating several types of microhabitat.
Another Beech growing nearby has a cavity, left, where a large branch of the tree had decayed near the base of the tree. The bark on the trunk supports lots of crustose lichens, below.
A Hop Hornbeam with a cavity, left, that measured 30 inches deep. Further up the trunk, a knothole was provides habitat for moss.
In a nearby Hop Hornbeam, we spotted an unusual sight: another tree had, at some time in the past, fallen against the Hop Hornbeam, wedging in a fork in its trunk. Though the rest of the fallen tree was long gone, the short section that lay in the fork had become incorporated into the living tissue of the larger tree.
The large, loose plates of Shagbark Hickory bark provide shelter for insects, birds, and small bats.
Large, partially healed wound in the base of a Shagbark Hickory, right. Dried hickory leaves provide shelter for a spider and her web, below.
A forked White Oak twig supporting a spider web
Several species of fungi thriving on the bark of a dying White Oak.
Jan noticed a train of red American Winter Ants (tentative ID) moving up and down along a path among the bark plates of a Red Hickory, right. On the same tree a bracket fungus had established itself on the bark, below.
A network of Wall Scalewort, a species of leafy liverwort, spreads across part of the Red Hickory trunk. From a distance, liverworts look like moss, but up close you can see that the leaves are opposite while moss leaves spiral around their stems.
Kathryn spotted this slug on a Beech tree. After a while, it attempted to transfer to a nearby branch five or six inches away by curving over backwards. Alas, it did not make it on this attempt, falling into the fork of the two branches. This is likely a Carolina Mantleslug.
Don’s Pre- and Post-Ramble Observations:
An Aster stem rising above a cluster of goldenrod in the Children’s Garden is tipped with a tight bud. The rough hairs, the outwardly curved phyllaries, and the hint of purple at the top suggests this may be a Georgia Aster. Another clue is the timing – Georgia Asters typically bloom about a month later than other asters.
Nearby, a dew-covered Eastern Carpenter Bee in a deep state of torpor rested on a Rattlesnake Master inflorescence.
Later in the morning, the temperatures rose and Carpenter Bees got busy, in this case nectar-robbing a Candy Corn flower in the Visitor Center Plaza.
SUMMARY OF OBSERVED SPECIES
White Oak Quercus alba
American Beech Fagus grandifolia
Northern Red Oak Quercus rubra
Hop Hornbeam Ostrya virginiana
Red Hickory Carya ovalis
Winged Elm Ulmus alata
Hook Moss Leucodon sp.
Little Nest Polypore Trametes conchifer
White Micrathena orbweaver Micrathena mitrata
Shagbark Hickory Carya ovata
Hypoxylon Canker Biscogniauxia atropunctatum
Wall Scalewort Porella platyphylla
American Winter Ant (tentative ID) Prenolepis imparis
Carolina Mantleslug (tentative ID) Philomycus carolinianus
Candy Corn Plant Cuphea micropetala
Aster Symphyotrichum sp.
Eastern Carpenter Bee Xylocopa virginica
Rattlesnake Master Eryngium yuccifolium