Ray Riley, Loam Bio
Understanding of how carbon (C) enters and leaves soil, the largest active terrestrial C pool, represents a key research priority due to rising global temperatures associated with increasing atmospheric carbon dioxide concentrations. Microorganisms play a direct role in C retention in a wide range of terrestrial ecosystems through their inputs of dead cells (a.k.a necromass), which form a significant fraction of the soil organic C pool. Despite growing interest in characterizing the dynamics of fungal necromass decomposition as a critical factor impacting soil C persistence, only one study to date has tested how necromass decomposition rates may be altered by changing environmental conditions. Although that study suggests fungal necromass decomposition rates may in fact be sensitive to increased temperatures, possibly due to interactions with moisture availability, the unique environmental conditions of peatlands makes it unclear how representative these results are in normally drained upland systems.
To address current uncertainty in the sensitivity of fungal necromass decomposition to altered environmental conditions, we propose to conduct a field-based decomposition experiment at the University of Minnesota Cloquet Forestry Center in Cloquet, MN. Specifically, during summer 2023, we will incubate fungal necromass in the B4Warmed experiment, which includes a factorial combination of warming and reduced rainfall treatments. In addition to measuring how rates of mass loss from fungal necromass differ among ambient, warmed, droughted, and warmed + droughted treatments, we will also characterize how these treatments alter the structure of the microbial decomposer communities using molecular identification. Finally, we will analyze the chemistry of the remaining necromass to determine which components of decomposing fungal necromass are most sensitive to warmer and drier conditions. “
Collectively, this study will provide critical insight into determining how altered environmental conditions impact fungal necromass decomposition, which will ultimately inform how soil C sequestration is being affected by ongoing climate change. Additionally, the work will create a new partnership between public university and private company scientists under the shared goal of mechanistically understanding how soil C can be effectively managed. The technical training of a graduate student will also help in building a more inclusive and diverse STEM workforce. Finally, through presentations at scientific meetings and involvement in community events, the PI and graduate student will share knowledge with diverse audiences about the links between soils, decomposition, and climate change.