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Fungi contribute to ecosystem function through nutrient cycling and decomposition but may be affected by major disturbances such as fire. Some ecosystems are fire-adapted, such as prairies which require cyclical burning to mitigate woody plant encroachment and reduce litter. While fire suppresses fire-sensitive fungi, pyrophilous fungi may continue providing ecosystem functions. Using litter bags, we measured the litter decomposition at three prairies with unburned and burned sections, and we used Illumina sequencing to examine litter communities. We hypothesized that (H1) decomposition would be higher at unburned sites than burned, (H2) increased decomposition at unburned sites would be correlated with higher overall saprotroph diversity, with a lower diversity in autoclaved samples, and (H3) pyrophilous fungal diversity would be higher at burned sites and overall higher in autoclaved samples. H1 was not supported; decomposition was unaffected by burn treatments. H2 and H3 were somewhat supported; saprotroph diversity was lowest in autoclaved litter at burned sites, but pyrophilous fungal diversity was the highest. Pyrophilous fungal diversity significantly contributed to litter decomposition rates, while saprotroph diversity did not. Our findings indicate that fire-adapted prairies host a suite of pyrophilous saprotrophic fungi, and that these fungi play a primary role in litter decomposition post-fire when other fire-sensitive fungal saprotrophs are less abundant.
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Plant and microbial feedbacks maintain soil nitrogen legacies in burned and unburned grasslands
Abstract Nitrogen (N) availability is a well‐known driver of ecosystem structure and function, but as air quality regulations continue to reduce atmospheric N deposition, there is a need to understand how managed and unmanaged ecosystems respond to widespread decreases in terrestrial N availability. Historical N eutrophication, from pollution or fertilisation, may continue to constrain contemporary responses to decreases in available N because of altered plant and microbial feedbacks. Thus, while certain management practices like prescribed fire remove N from grassland ecosystems, the role of fire supporting ecosystems recovering from chronic N input is unknown.To address this knowledge gap, we ceased a 30‐year N‐fertilisation treatment at a field experiment in a tallgrass prairie ecosystem crossed with burned and fire‐suppressed (unburned) treatments. We established subplots within each previously fertilised, recovering plot, fertilised at the same historical rate (10 g N m−2 year−1as NH4NO3), to compare plant and soil properties in recovering plots with control (never‐fertilised) and still‐fertilised treatments within different fire regimes.We document different N‐fertilisation legacies among ecosystem properties in burned and unburned prairies recovering from N‐fertilisation. Soil N availability, nitrification and denitrification potentials in recovering plots remained higher than controls for 3–5 years—indicative of positive legacies—in both burned and unburned prairies, but burning did not reduce this legacy. In burned prairies, however, a positive legacy in above‐ground plant production persisted because a more productive grass species (switchgrass) replaced the previously dominant species (big bluestem) even though root C:N, but not soil C:N, increased to return back to control levels. Consequently, the main N loss pathways in burned and unburned prairies (pyrovolatilisation and microbially mediated processes, respectively) led to similar losses of soil total N (20–28 g N m−2) over 5 years.Synthesis: Our results indicate that N eutrophication induces positive legacies of ecosystem functions that can persist for at least half a decade. N‐induced legacies arise because of shifts in soil microbial N‐cycling and plant functional traits. As a result, different management practices may elicit similar trajectories of ecosystem recovery in terms of total and available soil N because of different plant and microbial feedbacks.
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- Award ID(s):
- 2025849
- PAR ID:
- 10547671
- Publisher / Repository:
- British Ecological Society
- Date Published:
- Journal Name:
- Journal of Ecology
- Volume:
- 112
- Issue:
- 9
- ISSN:
- 0022-0477
- Page Range / eLocation ID:
- 2093 to 2106
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1111/1365-2745.14386
