The Forest, The Cicadas, and The Holey Fluxes: periodical cicada impacts on soil respiration depends on tree mycorrhizal type
Abstract
The simultaneous emergence of billions of periodical cicadas can have profound impacts on plants and animals in the forests, but the degree to which the cicadas impact soil carbon dynamics are poorly understood. For instance, each individual cicada creates its own emergence hole which has the potential to increase soil aeration and water infiltrationboth of which affect tree physiological and soil microbial activity along with CO2 fluxes. However, the directionality and magnitude of the response is challenging to predict, as macropore formation increases oxygenation of the soil promoting autotrophic and heterotrophic respiration whereas saturating soil creates anerobic microsites that limit CO2 exchange with the atmosphere. Here, we took advantage of the emergence of billions of cicadas from the 2021 Brood X in the US eastern forests to investigate 1) How do cicada emergence holes affect soil respiration (RS) and 2) to what extent do these effects vary among forest plots dominated by trees that associate with arbuscular mycorrhizal (AM) versus those that associate with ectomycorrhizal (EcM) fungi? Soil CO2 efflux was measured systematically at three sites in southern Indiana containing respiration collars with zero, one, or two cicada holes. Collars were installed along hillslope and AM-EcM gradients to address the variation of RS relative to forest composition and topography. Generally (across all collars), EcM sites had a 14% greater RS rate than AM dominated stands. RS in AM stands increased by 31% and 57% for collars containing one or two cicada holes, respectively, relative to areas without cicada emergence. EcM sites had a 2% and 25% increase with one and two cicada holes, respectively. In mid-summer (i.e., 6-7 weeks after cicada emergence), cicada holes began filling up with soil, resulting in a little difference in RS across the landscape. The short increase of RS consequence of the cicada emergence is estimated to have increased the annual CO2 efflux; however, the legacy effects of the 17-year event are likely to be short lived. These data provide novel insight into the coordination of carbon stocks, forest composition, and the potential consequences of shifts between AM and EcM dominated stands while illustrating the responses of RS to environmental perturbations following cicada emergence.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.B25B1448B