Soil Dynamics

So know that you know a little bit about the tundra and the permafrost, it seems appropriate to explain how Amanda Koltz’s research connects to the permafrost and the tundra. As mentioned in my last post, an important part any ecosystem is the process of decomposition in the soil layer, which happens a bit differently in permafrost soils. There are LOTS of tiny little creatures in the soil that help to break down the dead material in the soil, which range from bacteria and fungi (decomposers) to mites, springtails, beetles and more (detritivores). De-what? Decomposer? Detritivore? There’s a difference? Yes.

Tundra Mushrooms
Typical fungi on the tundra. Note my boot in the lower portion of the photo for size.
Collembolans
Collembolans (springtails) are classic detrivores. Collembola are smaller than the head of a pin! Image courtesy of Wikipedia.
Decomposers are organisms (usually bacteria and fungi) that feed on detritus (plant litter/dead matter/waste), breaking it down into its simplest forms (i.e. chemical elements and nutrients) and release them back into the soil. Decomposers usually work through the use of enzymes and can be thought of as “nature’s recyclers.” Detritivores are a little different. Detritivores are multicellular organisms (springtails, beetles, mites, even earthworms) that feed on the bacterial and fungal decomposers themselves (and sometimes some detritus too). Detritivores cannot break down dead material to the level a decomposer can, but they have an interdependent relationship that is vital to the recycling of nutrients that other organisms (like plants) need throughout the soil.

Amanda Koltz and Team Spider

Amanda Koltz, a PhD candidate at Duke University, is interested not only in these soil dynamics, but also how they are influenced by a predator like the Arctic wolf spider. The wolf spider is what is known as a “generalist” predator, meaning it does not discriminate when it comes to food (an opportunist). The wolf spider is small, so that means it eats a lot of small things. Can you guess what? Yep…detritivores.

Ice Spider
Wolf spider resting on snow. Image courtesy of Kiki Contreras.
So how does the wolf spider influence the structure of this detritivore web? And does our changing climate impact their role within this web? Remember, the permafrost here in the tundra has a lot of stored carbon, and the decomposers and detritivores have a pretty important role in releasing and recycling that carbon. Since many scientists believe that the permafrost is thawing at a slightly accelerated rate these days, there are a lot of questions that have arisen about the detrivore food web. These are the questions that Amanda is hoping to answer through her research here at Toolik. Keep reading my journals to figure out exactly how Amanda is conducting that research and why it is important to understanding the possible impacts of global climate change on an ecosystem level. I’ll explain her experimental design in greater depth in a future journal, but for now, here are a few pictures to start you thinking about what she (and the rest of Team Spider) is doing!
Spider Plots
View of spider plots with Toolik Lake in the distance.
Typical Plot
Typical spider plot. All plots are covered to keep out flying insects, but some plots, like this one, are covered with a thick plastic to act as a greenhouse and simulate warming tundra.

Scope Work
Sarah and Amanda identify spiders (and other critters) recovered from pitfall traps under high powered microscopes.

Author
Date
Location
Toolik Field Station
Weather Summary
Rainy and gray
Temperature
46
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