The ice has finally melted on most of the local conservation area trails, and for the first time in months, I’m no longer wearing spikes! With the trails clear, Trooper can safely tackle more challenging terrain and we took our first hike on bare ground at Fox State Forest this week.
Though the ice was gone, I found myself unsure of my footing in certain areas thanks to the masses of acorns scattered across the trail. While the dogs paused to investigate an array of scents, I took a closer look at the acorns and noticed that some were beginning to crack open and germinate. This raised an interesting question: since most acorns fall in the autumn, why do some begin to germinate only now, in the spring?
Red and white oaks are closely related but have different reproductive strategies. In New England, red oak (Quercus rubra) and white oak (Quercus alba) can be distinguished by their leaves—red oak leaves have pointed lobes, while white oak leaves have rounded ones. (When I was learning to identify trees years ago, I used mnemonic devices and remember “White is wound,” to help recall the softer, rounded edges of white oak leaves.)
Division of Fisheries and Wildlife. (2021, June 29). White oak and red oak leaves. [Photograph]. The Mighty Oak. https://www.mass.gov/news/the-mighty-oak
The differences go beyond leaf shape, they also have distinct acorn development cycles. White oak acorns mature in just one season, falling to the ground in autumn and quickly germinating before winter sets in. In contrast, red oak acorns take two seasons to mature. They fall in the autumn but do not germinate until the following spring (Johnson, 2019).
Squirrels and chipmunks have picked up on this difference and can distinguish between the two when caching food for winter (Johnson, 2019; Zhang et. al., 2023). When they store white oak acorns, they often bite into them and remove the embryo—the portion of the nut where growth begins—to prevent sprouting. This allows them to keep the acorn viable for longer storage. Red oak acorns, with their delayed germination and higher tannin content, can be safely stored without this extra step, as they won’t sprout until spring regardless (Johnson, 2019; Zhang et. al., 2023).
This staggered germination is an example of how species evolve strategies to minimize direct competition. Since red and white oaks share the same habitats, natural selection has likely favored staggered germination to ensure both species can successfully reproduce without directly outcompeting one another. This evolutionary divergence, known as character displacement, helps maintain a balance between the two species (Krohne, 2015).
Perhaps these strategies aren’t just about competition, and we can take a different perspective; they also reflect cooperation as each species’ survival is deeply linked to the survival of those around it. After all, no species exist in isolation. Life thrives in communities of connection and interdependence.
References
Johnson, P. S., Shifley, S. R., Rogers, R., Dey, D. C., & Kabrick, J. M. (2019). The ecology and silviculture of oaks (Third edition.). CABI.
Krohne, D. T. (2015). Competition. In Ecology: Evolution, Application, Integration (pp. 227–247). Oxford University Press.
Zhang, M., Yang, X., Dong, Z., Liu, S., Chen, H., & Yi, X. (2023). Behavioral adaptation of sympatric rodents to early germination of oak acorns: radicle pruning and embryo excision. Frontiers in Plant Science, 14, 1135312–1135312. https://doi.org/10.3389/fpls.2023.1135312