I would like to tell you a story. A painfully oversimplified story, but a good one nonetheless. While this is my version of the story, it is by no means only mine. This is just another story of life on this planet and its relation to other living things. I hope you enjoy!
Our story starts with a tree. The tree is old and it is dying. This is okay. Throughout its long life the tree has produced millions of seeds and it is likely that at least a few of them are in the process of growing into new trees. It has replaced itself, the crowning achievement of all life on this planet. The tree has been through a lot during its time on Earth but now its life is coming to an end. You see, the tree has an infection. A fungal spore landed and began to grow on the scar of a branch that broke off during a wind storm.
The fungus is now spreading through the tissues of the tree. It started slowly at first but now it has reached critical mass. The fungus is consuming living tissues faster than the tree can repair them. It is a losing battle for the tree but a winning one for the fungus. As more and more of the tree dies, the dead wood becomes soft with yet more fungi. The softer the wood gets, the more appealing it becomes to insects. Beetles can sense the tree is dying and they swarm all over it, laying eggs under the bark. These eggs hatch into beetle grubs that live on wood. Ants soon find the tree as well. They are carpenter ants and these ants are young queens. One of the queens begins laying eggs and soon a whole colony of carpenter ants is living within the wood of the tree. As they eat their way through the wood more and more of the tree is dying.
Soon the last vestiges of life disappear from the tree. Spring comes and no buds break, no leaves grow, and no more water is pumped through its tissues. The story of the tree does not end here though. Far from it. All this insect activity has brought some new attention to the tree. Woodpeckers love insects and they begin to descend on the tree with vigor. Because woodpeckers are so territorial soon only a single pair visits the tree. At first it is simply to eat the myriad of insects living within the tree itself but, as their bond grows stronger, the pairs focus soon turns to producing offspring of their own.
Instead of chipping shallow feeding holes into the tree, the pair begin to excavate a nest hole. This hole is much deeper, extending into the middle of the tree. With copious amounts of insects and a few trees under their control, the pair of woodpeckers successfully raise many woodpecker offspring summer after summer. The tree served them well. In the winter, the nest hole served to shelter a flock of chickadees from the extreme cold. The chickadees don’t know it but they owe their life to the woodpeckers for having excavated that hole. Winters are cold in this neck of the woods and without a place to gather together for warmth during the night, the little chickadees could have very well froze to death.
One summer the pair of woodpeckers do not return. Perhaps one of them flew into a car or got picked off by a cat. Either way, the nest hole was vacant one night when a flying squirrel found it. The squirrel was looking for a place to sleep during the day and the hole served her nicely. She stayed there all summer and into the winter. Like the chickadees, flying squirrels also congregate together in cavities during the winter for warmth. The hole suited them well. One of those squirrels happened to be a male that won her over come spring. Together they raised a small brood that year. Being fond of fungi, the flying squirrels were often covered in spores while feeding. These spores were brushed off in the hole whenever they returned home to their young.
These spores began to grow and, over the following seasons, the middle of the tree was nearly hollowed out. The tree stood for a few more seasons after this but finally, after years of insects and fungi eating it away, the tree collapsed. Again, this was not the end of the line for the tree. Soon the forest floor began to reclaim what was left. Fern spores landed on the waterlogged shell of the tree and there they germinated and grew. Moss spores did the same. In time a family of shrews made a den under the tree. Many a baby shrew was raised in this den.
One day a birch seed landed on the rotting bark. Here, far from competition on the forest floor, the seed germinated. The trees roots dug deep into the soggy tissues of the tree and soon found their way down into the dirt. Once in contact with the rich humus the trees growth took off. It rocketed into the canopy, vying for a place in the sun. Soon there was nothing left of the tree we started with. It rotted out from underneath the birch. Now, part of the humus itself, it went on to nourish the birch, which had become a full grown tree. One winter day a storm blew in. The storm brought with it a heavy load of snow. One of the birch’s branches couldn’t take the weight. With a loud snap that woke a sleeping owl, it crashed to the ground. The following spring a few fungal spores landed on the scar and started to grow into the birch.
hat tip to Virginia Native Plant Society