The Andrews is one of the places where scientists dared to gaze more attentively; and out of that emerged a revolution in understanding. Far from being “decadent,” these “old-growth” forests possess their own complex order as mature, biodiverse ecosystems. What appears as decay is essential to ecological flourishing.
That lichen cascading from the treetops—Lobaria oregana—turns out to be crucial. Nitrogen is a particular problem in a dense forest; the canopy closes after about a century, blocking the sun from nitrogen-fixing plants while trees are still young. Without this essential nutrient, they would fade long before reaching maturity. As the canopy closes, this lichen slowly establishes itself. Once established, it fills the gap, each year capturing tons of nitrogen per square mile that enters the soil as fallen strips decay on the forest floor.
Moss covering branches and trunks is often as old as the trees themselves. It plays an important role in capturing nutrients from the air and slowing the flow of rainfall down the tree so that nutrients remain near the trees’ roots. Rotting fungus, and bugs that consume dead trees, convert cellulose and lignin into soil nutrients that feed the astounding rise and near-millennial lifespan of these massive trees. Rot is itself life; there is more living tissue—bacteria, fungus, bugs—in a fallen tree than in a living one. Rising and falling, growth and rot, life and death are literally interconnected here.
None of this is obvious to a casual or even sincerely attentive observer. Much of it takes place outside the range of human sensation. Scientists struggle to broaden our scales of time and space in order to understand the hidden cycles of life. Learning the role of the lichen required chemical analysis and finding a way to work in the canopy, far above ground, to painstakingly measure the amount that grows on each branch. Knowledge of the cycle of log decay comes from an ongoing decomposition study that will follow the progress of fallen trees through the entire two hundred years it takes for a log to become soil. Gas emissions and fluid runoff are measured and analyzed. Bacteria, fungi, and bugs are microscopically cataloged, and their progress through tree tissue is carefully measured. This devotion and commitment from multiple generations of scientists certainly justifies considering the scientific a form of “serene attentiveness.”
This work attending to the fullness of creation has revealed astounding complexity. As we walk through the forest, we notice plants and animals around us, but often we literally miss the forest’s interconnections for the trees. The greatest part of its biodiversity lies below ground, where thousands upon thousands of species of worms, arthropods, and insects live, each hosting a different bacterial community in its gut. We used to think of soil as a test tube full of chemicals, but now know that it’s a complex biological network; we are only beginning to understand its thousands of parts. These are “trophic” networks: who eats what and whom. The complexity goes far beyond predator and prey. Everything from a fallen evergreen needle to a tree is consumed, and the droppings of the consumers are consumed by yet other species through cycles upon cycles.
Below ground lives another complex web that facilitates one of the most astounding sets of relationships in the forest: mycorrhizal fungi. Unlike saprophytic fungi which live on decaying matter, mycorrhizal fungi live in symbiosis with living plants. Scientists have known these soil fungi are important for more than a century. Only in the past few decades, however, have they found ways to study the complexity of these relationships in detail. Electron microscopes show that mycorrhizal fungi filaments surround and penetrate plants’ root hairs. On the most basic level, trees share sugars with the fungus; the fungus extends their root systems’ reach a thousand-fold into microscopic nooks and crannies. The underground portion of fungi is much larger than the mushrooms we see. DNA analysis reveals that they can extend for hundreds of yards or even miles, linking the root systems of many trees, including different species, into a network that shares nutrients, water, chemical alerts, and even electrical signals. Using carbon-14 isotopes, Susan Simard famously found evidence of Douglas firs sharing sugar with birches in the spring and fall, and receiving sugar back when they leafed out in the summer. Older trees not only nurse their young through these networks; they serve as anchor points of complex networks that link entire stands of trees. One study found as many as sixty-five separate fungus species forming root networks in Douglas fir forests.
This research is breathtaking. Far from a ruthless competition of individuals for water and nutrients, we find diverse communities supporting their members. Vast, complex, multi-species networks thrive by sharing resources and information. The vocabulary used is as consonant with Catholic social thought as the reality it describes. The technical term used for these multispecies networks is “cooperative guilds.” There is a common good in the forest.