The leaves are changing, but it's not what it used to be
Climate change has caused shifting of autumnal colors brought to you by trees. It used to happen in October, but now it’s November. Remember the discontinued October Color Cruise? This year November instead marks the peak for local fall foliage. Beauty for the beholder? Meh!
Oh, there’s a brilliantly colored tree here and there in someone’s front yard, but timing for color change in individual tree species is off so forests don’t show that short term blast of synchronized colors. Local weather conditions have not helped either. Many tree species have kept leaves longer, but they tend to just turn brown before dropping.
Even given color disappointment, deciduous tree leaf dropping is amazing. We are extremely fortunate to live in this temperate rain forest where we can bear witness. So, as is my custom (usually in October), here is my annual description of tree preparation for winter and what happens before each leaf falls:
With the tilt of the Earth, it’s clear that there will be less light for photosynthesis for food making, and water will be harder to get. Trees begin to shut down. At the base of each leaf is a small corky layer that swells and cuts off the flow of water. With no access to water, green chlorophyll disappears and we see the color of the leaves underneath. Eventually, the corky layer forms a disintegrating cell line that says ‘tear here’ and so each leaf falls to the ground. It’s a miraculous process.
But that’s not all. When leaves fall to the ground, if we don’t rake them away, they decompose first with the help of earthworms, beetle larvae, millipedes, mites, slugs, snails and microbes and then with acids and enzymes released by fungi. This complex process releases water, carbon, and inorganic nutrients back into the soil for reuse by plants through their root systems. It’s a grand recycling scheme.
There’s more! What scientists are now learning about trees in a forest is that they communicate with each other via fungi (mycorrhizae) that provide nutrients and water to the roots. They also form a community linked through a fungal pipeline to the root systems of other nearby trees.
Compare it to a human brain nerve network sending out signals to assess conditions for staying alive. A tree attacked by insects can send messages to other trees connected by the fungi warning them to set up their defenses. They can share carbon and nutrients. Older ‘mother trees’ can even recognize their own seed kin.
This forest community works to help all survive—a lesson for human communities might operate. Protecting each other, especially family members, warning against approaching disease and other dangers, acquiring food for survival, and sharing are all traits we value for survival. That’s what forests do. Isn’t that way worthy for humans to emulate?
Recent discussions in Chattanooga about ways to protect our steep slopes and floodplains highlights how little we value our forest communities despite the many free services provided for us humans. Trees provide air and water cleaning, erosion prevention, ecosystem balance and slowing of climate disruption through carbon sequestration. Yet, to build a shopping center, a stadium for an unneeded second soccer team, or another subdivision, we wantonly destroy our forested communities or an elderly beloved Post Oak.
In Richard Powers’ recent novel “Overstory”, he highlights several fictional characters tracking their lives as they build relations with certain trees and forests. Over their lives, the characters fight predominant attitudes about what brings quality to lives and the human species.
Meanwhile the trees stand sentinel, silently watching as humans chop away at the resilience built into natural ecosystems and push for ever more expanding growth within a finite system. As forests adapt to changing situations, what signals are they sending out to address human folly?
In most religions there exists a symbolic tree of life. For some it means the knowledge of good and evil. In others it’s the home of tree spirits. Many say the tree of life is the Baobab tree in Bahrain that can live up to 5,000 years. Still others think of the tree of life as a scientific metaphor for evolution research describing relationships between organisms, living and extinct.
Whatever your belief about the tree of life, trees are wondrous beings that know ways to live in community. We ignore and destroy them at our peril.
Sandra Kurtz is an environmental community activist, chair of the South Chickamauga Creek Greenway Alliance, and is presently working through the Urban Century Institute. You can visit her website to learn more at enviroedu.net