Forest soil at the end of the year’s long exhale

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.

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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.

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8 thoughts on “Forest soil at the end of the year’s long exhale

  1. Stephen Truslow

    I’ve hiked all over the upper reaches of the New Hampshire White Mountains and also Old Speck in Grafton Notch and your pictures do the ecosystems there justice. It’s an amazing environment. We’ve had a drought in the northeast but the colors up in the mountains has been spectacular. I marvel at the beauty of the mosses, especially deer mosses, and lichens. Because of the effects of glaciation, there are large boulders that have colonies of mosses and trees growing on them. Wonderful!

    Reply
  2. lakeontarian

    Hmmmm, how does the annual needle drop get through to the duff on which the boreal mosses grow so luxuriantly?

    Reply
    1. David George Haskell Post author

      Ah, great question. The most luxuriant moss pictures are from rocky surfaces at higher elevations where litter fall is lower. Duff is deepest in heavy shade under large trees. Given that, I oversimplified in this post. I have seen moss, though, grow plenty fast enough to engulf the needle fall and swallow it under a surface of green. Moss also intercepts dust and other atmospheric deposition, keeping it away from the tree roots and leaf litter below, further slowing decomposition by nitrogen starving the microbes below. If the moss layer is taken away, decomposition rates go up.

      Reply
  3. Doug

    Here in northern Wisconsin, it is exotic earthworms that have destroyed the duff layer. There are no native earthworms here; all were eliminated by the glaciers. One can tell the difference by the way the soil feels underfoot between a forest stand with worms and the increasingly rare stands without worms.

    Reply
  4. Scott

    Like Doug’s soils, the soils in the northern Piedmont are all turned over, processed, and depleted (probably several times this year already) by non-native earthworms. In fact, the soil is hardly soil at all–it’s worm castings! Our “soils,” too, are very, very dry.

    Reply
  5. Domus Americanus

    Wow. First of all I appreciate your calling Corker to task for his mind-numbing vote of confidence in a certifiable scam artist of the Orwellian sort. Given the tone of his staff response to the crossing of paths it is a good reason for all elected officials to wear body cams to insure that the citizenry are indeed protected. Secondly, I appreciate all that I have learned of your Domain, and what my daughter Elsie Spencer (a student of yours I believe) has taught me. And lastly, I thought you might enjoy this recent blog post of my own on Sewanee and All Saints.
    https://domusamericanus.net/

    Cheers!
    Madison Spencer

    Reply

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