European Hamster

Every autumn, the European hamster stockpiles several kilograms of grain in its burrow's larder to get through winter. Without it, from the very first year, these food stores are no longer built up, and the tunnels it dug and maintained — sometimes more than two meters deep — start collapsing in the fields it once occupied.

Ten years later, those tunnels have long since collapsed: the soil they once loosened and aerated settles back into the same compact, uniform structure as the rest of the continuously farmed fields, with no loose pockets left from the hamster's digging.

Over a century without it, the land would never regain the network of deep tunnels the hamster once dug there: it would stay just as compact and uniform as it had already become within the first decade.

Over a thousand years, even a return of the European hamster wouldn't close the gap: rebuilding a tunnel network as deep and dense as before would take generations, and for a long stretch the soil would stay closer to the compacted ground it had become than to the original underground network.