Student view:

Allison Zahorec: Studying Microarthropods

Dec. 4, 2019

Allison Zahorec is a doctoral student studying in the Landis Lab in the Department of Entomology.

Acclaimed biologist E.O. Wilson dubbed invertebrates as “the little things that run the world.” More than 95% of all animal species are invertebrates, with species adapted to thrive in the driest of deserts to the ocean depths. Despite their hidden lifestyle, they can have potentially large impacts on key ecosystem processes important for reducing further climate warming.

Since starting my Ph.D. in entomology, I’ve become especially fascinated by one group of tiny soil-dwellers, the microarthropods. Species in this diverse collection of arthropods are often as small as a poppy seed, with thousands living in a square meter of even the most intensively managed agricultural soils. Though tiny and inconspicuous, recent studies show evidence that microarthropods could have an important influence over the soil carbon cycle, a process critical for lessening our impact on the climate.

Soils hold more carbon than plants or the atmosphere combined, making their ability to store carbon long-term an important factor for achieving carbon dioxide emissions goals. While the role of microarthropods on soil carbon dynamics has not received as much attention as that of plants and microbes, these soil-dwellers may have significant effects on the ability of soils to build carbon by breaking down plant residues and influencing microbes through their feeding. 

I have always been intrigued by how ecological interactions between organisms drive ecosystem services. The potential for this research to help address climate warming, one of the most pressing issues of our time, is incredibly exciting for an early ecologist as myself.

While microarthropods are present in virtually all soil habitats, my biggest focus is investigating the role of microarthropods on soil carbon in bioenergy cropping systems. Bioenergy cropping systems are utilized for growing plants to convert into renewable energy forms and will likely increase across the landscape as we move away from fossil fuels. Farmers growing crops for bioenergy must make numerous decisions about which crops to grow and how to manage their fields.

The impacts of these choices on existing soil carbon pools are poorly understood, something that I and other researchers through the Great Lakes Bioenergy Research Center, or GLBRC, are hoping to change.

The GLBRC supports a wide range of research initiatives such as this project with the goal of developing sustainable bioenergy products. I hope that my research findings can contribute to sustainable management options for bioenergy farmers that will maximize soil carbon storage.

My first research objective was to investigate how bioenergy crop type and management intensity influences microarthropod community structure. This required surveying microarthropods from annual, conventionally managed farm systems to relatively undisturbed perennial prairies. However, studying animal populations is not so straight-forward when the animals you are looking for are very small and live underground.

To be able to identify and quantify microarthropods, I, along with others from Doug Landis’ lab, collected soil and plant litter samples from a GLBRC site at the Kellogg Biological Station and brought them back to the lab on campus. There, we placed them in Tullgren funnels, which involves placing a lightbulb over the samples to mimic the sun on a hot day. The microarthropods inside the soil move down the funnel to avoid the heat and eventually fall though a mesh screen into a container, allowing us to collect them for identification. 

Preliminary results from this survey indicate that minimally disturbed perennial bioenergy cropping systems support the greatest numbers of microarthropods, though different microarthropod groups vary in their habitat preferences. Now knowing how microarthropod communities differ across bioenergy cropping systems, my next steps are to investigate how these differences in microarthropod community structure influence microbial and plant functions pertinent to building soil carbon.

I am hopeful that these and further findings will further reveal how highly abundant and diverse soil invertebrates help run the soil ecosystems they call home.

Read more about the Great Lakes Bioenergy Research Center here.