There is a slumbering subterranean fire in nature which never goes out, and which no cold can chill.
-Henry David Thoreau, A Winter Walk (1843)
Winter is upon us, and what better way to beat the indoor-blues than with a crisp afternoon walk through the Arboretum? While autumn’s hues have come and gone, a world of color awaits on the forest floor. Late fall and winter is an ideal time for searching out those ecological players who go unnoticed during the growing season’s splendor.
During a mid-week visit to the Arboretum’s beech grove, I stumbled upon the felled trunk of a once-stately American beech (Fagus grandifolia), left to decompose among the surrounding leaf litter and debris. A few minutes of close observation revealed an abundance of colorful organisms living among the old tree’s rotting wood, and my plan to spend the day photographing the oak collection quickly fell by the wayside as I poked and prodded my way through the decaying matter.
A decomposing tree provides an invaluable supply of nutrients and a protective, moist habitat for a variety of life forms. Lichens—composite organisms consisting of algae or cyanobacteria living symbiotically among fungus—are brought to life by the late-season precipitation. Greenshield, British soldier, and crustose rock disk lichen feed themselves through photosynthesis and serve as an important source of food for animals and other fungi. The decomposing tree is an ideal substrate to support these curious organisms.
The brilliantly-colored fungi that I spotted, such as turkey tail, witch’s butter, and tinder conk, lack the autotrophic properties of lichen, and depend on the decaying beech wood for more than shelter. Fungi are important members of forest ecosystems for their ability to break down organic matter and form symbiotic connections with living plants. However, the presence of fungi is not always welcome; the sinister Neonectria faginata is a particularly voracious pathogenic fungus that may have caused the decline of this beech tree. Its fruiting bodies appear as pestilent red spots protruding from the grayish bark.
Epifagus virginiana (beech drop), standing only 10″ tall and lacking chlorophyll, is not actually a fungus, but a parasitic plant. While beech drop subsists wholly on nutrients from the roots of American beech trees, it is not believed that this plant does significant damage to its hosts. The delicate white and purple flowers of beech drop occur from July through October each year.
Cold temperatures are no excuse for dormancy! These last remaining snow-less weeks are ideal for close observation at the Arboretum. Grab your hat and gloves, and come find a world of organisms hidden among the wintry landscape.
If you’re interested in learning more about phenology, botany, or ecology, join the Arnold Aboretum Tree Spotters, a group of citizen scientists who collect data from 11 species throughout the Arboretum to assist studies focused on plant responses to climate change. Read more about Tree Spotters in Silva [pdf].