Living organisms rework soils through bioturbation, altering the structure of soils on which most terrestrial ecosystems are based. These organisms include invertebrates (i.e., earthworms) and burrowing mammals (i.e., moles) that mix nutrients into belowground layers through their burrowing. Because of this, bioturbation is often positively correlated with increased soil nutrients, which alters soil chemistry and can even shift plant communities and ecosystem function. Certain plant communities may also attract (or repel) particular burrowing organisms, thus there may be important (but unknown) feedbacks between burrowing activity, plants, and soil properties. In an experimental prairie restoration, our research is exploring 1) if bioturbation and plant community properties are correlated and 2) if plants and burrowing are related to soil nutrients. In 1 m2 plots, we collected data on mammal burrowing and plant communities for two years, and are now analyzing soils for different nitrogen pools. Overall, our research will link bioturbation, plant communities, and soils to improve our fundamental understanding of terrestrial ecology and better guide habitat restoration efforts.
Results/Conclusions
Burrowing measured in 2016 correlated spatially with burrowing in 2017, meaning areas that were highly impacted the year before followed that pattern a year later. Areas with large amounts of vegetation in the fall were less likely to have mammal burrowing in the spring. These results suggest bioturbation patterns are not random, but have some predictability from year to year. Vegetation composition and burrowing levels also appear related. For example, areas with greater percentage of grass cover in Fall 2015 had lower burrowing in Spring 2016. Finally, plots farther from the edge of the experimental area consistently had higher burrowing levels in both years. To determine chemically how soil structures are being altered from burrowing, data will be collected in the Summer of 2017 to quantify levels of nitrogen. Both ammonium and nitrate will be quantified, determining how burrowing affects nitrogen allocation in soils. Overall, our work relates burrowing disturbance to both plant communities and physical and chemical properties of soil, with a goal of a deeper understanding of the complex interactions of plants, animals, and soil processes in prairie restorations.