On a chilly Friday morning in late October, the BCM and ECM cohorts crowded into two coaches. The location was only a short trip from Oxford city centre, but quick glances between hedges from the coach windows revealed we would be spending our day surrounded by trees.
Wytham Woods is not just a regular forest: it is an ancient forest owned by Oxford University for over 70 years. This woodland is clearly a Site of Special Scientific Interest: one path reveals a ladder connecting to a walkway in the canopy, while the other path leads to experiments controlling the amount of rain that falls on the grass.
But we did not come to Wytham Woods to conduct an experiment; we came here to put lectures from our Global Change and the Biosphere class into context. Led by Professor Yadvinder Malhi, we entered the forest along the muddy path littered with leaves.
We first learned that the trees in this forest act as Oxford’s carbon sink. This means that the trees absorb about 25 percent of the fossil fuels emitted by Oxford’s residents. Tackling climate change means preserving forests like Wytham Woods.
As we walked deeper into the woods, envious of those that thought to wear their Wellington boots, we turned our attention to the leaves that still clung to the branches, refusing to fall so soon. We considered the differences between ash and oak leaves. Ash leaves are compound, meaning they are made up of leaflets that let light pass through to the forest floor. Plants that live under ash trees differ from those under oaks because oak leaves are more substantial and allow less light to pass through. But ash trees are suffering from ash dieback, a fungal disease that causes leaf loss and death, meaning fewer ash trees can now be found in Wytham Woods. This gap in the forest encourages other tree species, like oaks, to increase their abundance. More oaks changes the overall amount of light that reaches the forest floor. A darker forest means different plants can grow, or not grow, below the trees. When one species increases or decreases in numbers, it can modify the rest of the forest, too.
With that in mind, we walked along a path that borders the edge of the forest. We could just about see through the trees to farmland on the other side. Here we learned that forest edges are drastically different from the middle of a forest. Pesticides and fertilizers from a nearby farm may make their way into the forest from the edge. More light is let through, influencing what species can grow there. The damp forest that many of us think of does not exist close to the edge: more light creates a dryer habitat. Forest centres are moister, meaning decomposition can occur at a higher rate thanks to the insects that prefer a wetter habitat. The forest centres are more resilient to outside forces, such as pests, pollution, and climate change.
This has a direct connection to conservation management strategy. If forest centres are healthier and more resilient than forest edges, then increasing the centre will create a more robust forest. Planting more forest or protecting land around an existing forest may be a better conservation management approach than creating a new protected area in a different location.
After a full morning of relating forest ecology to biodiversity and conservation, many of us began digging into the food we had packed. We spread out among fallen trees to eat our lunches. We considered all that we had learned: from the complicated forest dynamics to the seemingly simple changes that impact the forest as a whole. We also thought about what Wytham Woods may have looked like when large, now extinct, elephants once roamed these lands. We looked around us and wondered if a lack of native trees and an incomplete canopy is better than an interconnected canopy comprised of nonnative trees.
After lunch, we walked back to the coaches. Those of us who slipped in the mud brushed the remaining dirt off our jeans and scraped our shoes off on the grass. We boarded the coaches and wondered which of us would return to Wytham Woods to collect research for our dissertations.
All photos taken by Daniel Oberhauser.
Charlie Chesney is a BCM student interested in investigating the various causes of population decline from both a social science and natural science perspective. She plans on pursuing a career in academia and science media.