00502nas a2200133 4500008004100000022001400041245009800055210006900153100002200222700002400244700002200268700002300290856005500313 2025 eng d a1752-089400aDecadal persistence of grassland soil organic matter derived from litter and pyrogenic inputs0 aDecadal persistence of grassland soil organic matter derived fro1 aLeuthold, Sam, J.1 aSoong, Jennifer, L.1 aEven, Rebecca, J.1 aCotrufo, Francesca uhttps://www.nature.com/articles/s41561-025-01638-y00633nas a2200169 4500008004100000245014200041210006900183300001100252490000800263100002500271700001800296700001800314700002000332700001600352700002300368856007200391 2023 eng d00aThirty years of increased precipitation modifies soil organic matter fractions but not bulk soil carbon and nitrogen in a mesic grassland0 aThirty years of increased precipitation modifies soil organic ma a1091450 v1851 aRocci, Katherine, S.1 aBird, Michael1 aBlair, J., M.1 aKnapp, Alan, K.1 aLiang, Chao1 aCotrufo, Francesca uhttps://www.sciencedirect.com/science/article/pii/S003807172300207902650nas a2200277 4500008004100000245010000041210007100141300001400212490000700226520171400233653000901947653002501956653001401981653002801995653002902023653002002052653002202072100002402094700002602118700002402144700001502168700002002183700002302203700001502226856013102241 2017 eng d00aBelow‐ground biological responses to pyrogenic organic matter and litter inputs in grasslands0 aBelow‐ground biological responses to pyrogenic organic matter an a260 - 2690 v313 a

1. Terrestrial ecosystems are often burned by both managed and wildfires. During a fire, the above-ground biomass that would typically accumulate and be decomposed as litter on the soil surface is combusted. Pyrogenic organic matter (PyOM) remaining after a fire is a considerably more recalcitrant organic input to the soil than fresh litter. The activity and community composition of soil organisms responsible for decomposition of organic matter and nutrient recycling in the soil could thus be affected by altered resource availability caused by frequent fires.

2. We examined the effect of PyOM vs. fresh litter inputs to soil biota at both an annually burned and an infrequently burned tallgrass prairie site by tracing (13) C-and N-15-labelled litter and PyOM into growing plant roots, microbial phospholipid fatty acids (PLFAs) and soil nematodes for 1 year.

3. Litter-derived C or N was incorporated into microbes, nematodes and roots, while PyOM contributed minimally to soil microbes and plant roots and was not detectable in nematodes. Soil microbial and nematode abundances in the PyOM amended plots did not significantly differ from the bare soil plots, but nematodes were more abundant and microbial PLFAs less abundant in litter-amended plots. The annually burned site had less predator and omnivore nematodes, with increased abundance of microbial feeders and greater microbial uptake of litter C.

4. An alteration of the soil food web structure caused by burning and the removal of the litter layer, along with the accumulation of non-microbially decomposed PyOM in the soil, contributes to the limitation of N cycling in frequently burned ecosystems.

10afire10alitter decomposition10aNematodes10aphospholipid fatty acid10apyrogenic organic matter10aStable isotopes10atallgrass prairie1 aNicolson, Susan, W.1 aWright, Geraldine, A.1 aSoong, Jennifer, L.1 aDam, Marie1 aWall, Diana, H.1 aCotrufo, Francesca1 aSala, Anna uhttp://knz.lternet.edu/content/below%E2%80%90ground-biological-responses-pyrogenic-organic-matter-and-litter-inputs-grasslands03655nas a2200133 4500008004100000245014400041210006900185260004800254490002100302520312300323100001403446700002303460856003803483 2014 eng d00aMoving beyond mass loss: advancing understanding about the fate of decomposing leaf litter and pyrogenic organic matter in the mineral soil0 aMoving beyond mass loss advancing understanding about the fate o aFort Collins, CObColorado State University0 vPhD Dissertation3 a

Leaf litter decomposition recycles the energy and nutrients fixed by plants during net primary productivity back to the soil and atmosphere from where they came. Traditionally, leaf litter decomposition studies have focused on litter mass loss rates, without consideration for where that mass ends up in the ecosystem. However, during litter decomposition by soil microbes a fraction of the litter mass lost is truly lost to the ecosystem as respired CO2, while another fraction remains in the ecosystem stored in the soil as soil organic matter (SOM). SOM is heterogeneous in composition, with various SOM pools remaining stored in the soil for time spans ranging from days to millennia depending on their biochemical and physical properties. Pyrogenic organic matter (py-OM) is the partially combusted plant residue left behind by fires, and has been found to contribute to long term SOM pools. SOM accounts for the largest terrestrial pool of carbon (C) in the global C cycle and stores nitrogen (N) and other nutrients for plant productivity. Therefore the formation of SOM during litter decomposition is critical to terrestrial C and N cycling and its feedback to global biogeochemical cycles. The focus of my dissertation is the study of leaf litter and py-OM decomposition, and quantitatively tracing how much decomposing litter and py-OM is used by soil microbes, how much is lost as CO2, and how much remains in the soil and contributes to SOM formation under different conditions. In order to best address my research questions, I first studied the methods of leaching of dissolved organic carbon (DOC) and 13C and 15N isotope labeling of plant material in the laboratory. Then, I conducted a laboratory incubation where I found that the amount of hot water extractable C and the lignocellulose index (Lignin/(lignin+cellulose)) can be used to predict DOM leaching, and the partitioning of C loss between DOC and CO2 from leaves and py-OM during decomposition. I also conducted two field studies using 13C and 15N labeled Andropogon gerardii leaf litter and py-OM to trace the fate of C and N losses during their decomposition in a fire affected tallgrass prairie, and understand the role of soil microarthropods in this process. I found that soil microarthropods increase the amount of leaf litter C that contributes to stabilized SOM formation during litter decomposition, by increasing litter inputs to the soil where they can be utilized by soil microbes. Finally, I found that frequent inputs of py-OM, rather than litter, due to annual burning of the tallgrass prairie alters the SOM formation process by removing relatively labile litter inputs to the soil and replacing it with py-OM that is unusable by soil microbes. Overall, my dissertation has focused on taking a mechanistic approach to understanding the process of litter and py-OM decomposition, and how their decomposition contributes to SOM formation and ecosystem CO2 fluxes. My results have helped to improve our understanding of terrestrial biogeochemistry, and the processes that control SOM formation during litter decomposition.

1 aSoong, J.1 aCotrufo, Francesca uhttp://hdl.handle.net/10217/83819