Imagine walking through a forest right after a wildfire. The trees are burnt, the ground is covered in ash, and almost everything that made the forest feel alive seems to be gone. Looking at it, you might assume that whatever grows next has to start completely from scratch. Surprisingly, that is not really what happens. Even after a major disturbance, pieces of the old forest can stick around and influence what comes next. Ecologists actually have a term for this: ecological memory (Johnstone et al. 2016).
Obviously, forests do not have brains, so what exactly are they “remembering”?
Instead of memories being stored in neurons, a forest’s past can be stored in things like surviving plants, roots, nutrients, and even seeds hiding underground. Johnstone et al. (2016) describe some of these as material legacies. There are also information legacies, which include traits that have helped species survive disturbances in the past. For example, some trees have cones that can protect seeds and release them after a fire. The tree is definitely not thinking, “I remember what happened last time.” But the traits left behind from generations of dealing with fire can affect how the forest responds today.
The part I found most interesting, though, is what can be hiding underneath our feet. Reed et al. (2025) studied how fire, gaps in the forest canopy, and deer affected a forest seed bank. Even 13 years after the experiment began, the different disturbances were still linked to differences in the seeds found underground. Even stranger, what researchers found in the seed bank did not completely match the plants they could see growing above ground (Reed et al. 2025). Basically, you could look at a forest and still be missing part of its history because some of it is buried in the soil.
Figure 1. Seed abundance and plant types found in forest seed banks after different combinations of fire, canopy gaps, and deer exposure (Reed et al. 2025).
As Figure 1 shows, the seeds left underground looked very different depending on what that part of the forest had experienced, showing how a disturbance can leave a biological trace years later.
But there is a catch. Remembering the past is only helpful when the future is somewhat similar. Climate change is altering things like the frequency and severity of forest disturbances, meaning forests can experience conditions that are very different from what they experienced historically (Johnstone et al. 2016). If a fire becomes intense enough to destroy the seeds, organisms, or soil conditions that normally help a forest recover, some of that ecological “memory” can disappear with it.
So, can a forest actually remember? Not in the way we can. But a forest is not starting with a blank page every time it is disturbed either. Its past can remain buried in its soil, written into the traits of its species, and carried by whatever survives. And with environments changing so quickly, maybe the bigger question is: what happens when a forest remembers a world that no longer exist.
References
Johnstone, Jill F., et al. 2016. “Changing Disturbance Regimes, Ecological Memory, and Forest Resilience.” Frontiers in Ecology and the Environment 14 (7): 369–378.
Reed, Samuel P., et al. 2025. “Multiple Disturbances, Multiple Legacies: Fire, Canopy Gaps and Deer Jointly Change the Forest Seed Bank.” Journal of Ecology 113: 353–370.
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