Skip to main content

Soil in spring

It's March. But the hard crust of snow on the ground is hanging around -- it's been too cold for it to go. A few days before spring, and the world still looks mostly frozen.

But the readiness is all, as far as soil is concerned.

"The soil wakes up before the trees do," said Peter Groffman.

Groffman is a microbial ecologist at the Cary Institute for Ecosystems Studies in Millbrook, N.Y. His area of expertise is soil ecology.

This winter, he said, has been a great one for soil -- one that should allow for interesting study in a number of areas.

It's been great because it's been both cold and snowy.

Snow acts as an insulator, he said. Get enough, and it's a nice blanket over the ground.

"In the North Woods, the soil never freezes at all," he said.

But, he said, those winters that turn cold, but don't deliver much snow are tough on growing things.

"The soil freezes, and there's a lot of damage to the roots of plants," Groffman said.

Because in winters like this, the soil will stay warmer under the insulating snow, it's ready to go into action as soon as the blanket leaves.

"When the snow melts and the sun shines on the ground, you can see a 4-degree jump in soil temperature in one day," he said.

That means leaf litter and fungus in the soil is quickly available to supply plants with nutrients, Groffman said.

But trees are purposefully slow to wake up. Because of the danger a late spring frost can do to leaves and buds, they've evolved to wait a bit.

That creates a vernal window in spring when some plants can get an early start on growing.

One good example of this are woodland wildflowers, Groffman said. The warming soil makes nutrients available. Without a lot of leaves on the trees, they get lots of sunlight, And we get trilliums.

Groffman said one thing the Cary Institute is studying is the impact of climate change on that vernal window.

If it's getting warmer earlier, he said, it may affect soil temperatures and the times when plants start growing. It may means trees start growing sooner.

"We want to know if that vernal window is getting wider," he said.

Groffman is also interested in earthworms. Did this year's cold winter and the deep snow affect them in any way?

"Normally, sometime in March, you suddenly find earthworms all over your driveway," he said. "At a certain point, when it gets to be 36 degrees or so, earthworms decide to go find their way in this world."

Groffman is also interested in seeing how this winter might affect a new invasive species -- Asian earthworms.

These are new species of very large worms -- genus Amynthas -- that people began using as bait. They've multiplied and headed out into the world.

All the earthworms we have are non-native invasive species, Groffman said. The earthworms we're used to seeing are European worms, brought over with plants by the first European settlers.

Probably none of them are good for the forest, Groffman said. They don't belong there and may be disturbing the soil in ways that are detrimental to woodland species.

But Asian earthworms, which are big, and tear through lots of leaf litter, are probably worse than their European counterparts.

"When I tell people earthworms are an invasive species, they think I'm nuts," Groffman said. "Now, when they see some of these big Asian earthworms, they listen a little."


Original Article >