In Shakerag Hollow, the leaf litter is down to almost nothing. Bare mineral soil, a few twigs. Last year’s downed leaves — once lying several inches thick — have now had their energy and matter dissolved away into the forest’s blood. In a few weeks, ground will fatten with a fresh fall of leaves, but for now all feels empty and exhausted. Six weeks of sunshine and no rain have added their burden: the soil is desiccated.
It was not always like this. At the peak of the last glaciation, the Cumberland Plateau was a spruce-fir forest, analogous to the boreal forests of Canada and the northern US. In such forests, cold temperatures, a short growing season, and more regular rainfall keep the soil’s litter well padded. Leaf litter seldom decomposes fast enough to reveal the mineral soil below. Instead, it builds into a spongy duff. Atop this bed, mosses and mushrooms exult. Contrast the photograph above with these images from Grafton Notch in a higher elevation forest in Maine. Time travel to the end of the Pleistocene.