by Swapna Subramanian
When I walked into forests, my eyes would immediately gravitate down. I’d ignore the light flitting through the tree leaves, ignore the swaying of the branches, ignore the ridged bark, and settle on the leaf litter and logs. What I wanted to see were the creatures that lived under the discarded, dead parts of the magnificent trees that most people go to the forest to see.
I cared about salamanders. I have always loved wiggly creatures, beginning with worms on sidewalks, and I began my first research project assisting my zoology and botany teacher with studying the diet of red-backed salamanders (Plethodon cinereus). When I caught my first red-backed salamander under the canopy of an old-growth forest, I fell in love with the forest. My free time was consumed with exploring forests, and I quickly learned how to identify the perfect log that a salamander might live under. Whenever I found myself in a forest, I spent my time flipping logs and inspecting the coarse soil underneath for the familiar red-striped back of a salamander.
My eyes were glued to the forest floor.
Our zoology and botany class went
on a field trip to a nearby forest. I got out of the van, and my eyes immediately dropped to scout out potential salamander abodes. My teacher began lecturing about trees. I continued my scanning -- trees were uninteresting. A salamander decides where it goes and what it eats; a tree simply stands there and provides a backdrop. As my teacher spoke, I discreetly flipped logs when no one was looking. Then I heard something intriguing:
“Plants employ many strategies to ensure their fitness.”
What? Plants don’t strategize, salamanders strategize! I tore my eyes away from a particularly tempting log and tuned in to my teacher’s lecturing. My eyes were opened up to the world above the salamanders.
Plant strategies actually begin below the salamanders, in the soil. Tree seeds often wait for the most optimal conditions to begin growing, and stay dormant in the seed bank until they have sufficient light and water. In forests with a dense canopy, this means that plants sometimes wait to start growing until another tree has fallen, and when that gap of light peeks through the canopy they grow very quickly to take advantage of the resource before other seeds do.
Plants have strategies as they grow as well. A huge problem in the forests of Pennsylvania is the abundance of deer, which resulted from the extirpation of their natural predators, like wolves. Deer now constantly come by and eat up tree saplings after they worked so hard to grow. But some plants have developed a way to avoid getting eaten- resistance. My teacher pointed to many trees and identified them as black cherry or red maple. These trees are ones that deer don’t like to eat, and now they are taking over the forest as the deer eat away the tree species that usually made up our forests like oaks. Plant strategy is changing the entire composition of forest tree species!
I used to always look down when I went into a forest. But when my gaze was pulled away from the forest floor and I learned that trees strategized, my viewpoint changed. I had been dismissing the trees because I thought they were boring, just standing pretty. But salamanders need the trees to drop their leaves and logs to make the abundant and diverse forest floor they live and hunt in. And the trees can only get up there if they end up getting sun and avoid deer predation, if they strategize. And which species of trees make it up to the canopy and drop their dead plant matter could affect the whole dynamic of the forest floor.
When I go into a forest today, my eyes take a different path. They sweep over the trees . . . and then go to the forest floor. I do still look for salamanders! But I have a more complete understanding of the forest. I see that a tree has fallen, resulting in a salamander log, but also note many young saplings growing to try and fill the canopy gap. I see an abundance of red maple leaves among the leaf litter, and I know the deer have been acting on this forest. I learned that to fully appreciate the forest, I can’t only look down. I also have to look up.
Swapna is an Ecology & Evolution and Anthropology undergrad at the University of Pittsburgh, who wants to make scicomm and outreach a big part of her career!
Photo Credits: Lead photo by Swapna; bottom two photos provided by Randy Cassell, Swapna's zoology and botany teacher who taught her to look up.