Details:

Journal Title:
Global Change Biology
Personal Author:
Carrara, Joseph E. ; Walter, Christopher A. ; Hawkins, Jennifer S. ; Peterjohn, William T. ; Averill, Colin ; ... More +
Carrara, Joseph E. ; Walter, Christopher A. ; Hawkins, Jennifer S. ; Peterjohn, William T. ; Averill, Colin ; Brzostek, Edward R. Less -
NOAA Program & Office:
OAR (Oceanic and Atmospheric Research) ; CPO (Climate Program Office)
OAR (Oceanic and Atmospheric Research) ; CPO (Climate Program Office) Less -
Description:
Atmospheric nitrogen (N) deposition has enhanced soil carbon (C) stocks in temperate forests. Most research has posited that these soil C gains are driven primarily by shifts in fungal community composition with elevated N leading to declines in lignin degrading Basidiomycetes. Recent research, however, suggests that plants and soil microbes are dynamically intertwined, whereby plants send C subsidies to rhizosphere microbes to enhance enzyme production and the mobilization of N. Thus, under elevated N, trees may reduce belowground C allocation leading to cascading impacts on the ability of microbes to degrade soil organic matter through a shift in microbial species and/or a change in plant–microbe interactions. The objective of this study was to determine the extent to which couplings among plant, fungal, and bacterial responses to N fertilization alter the activity of enzymes that are the primary agents of soil decomposition. We measured fungal and bacterial community composition, root–microbial interactions, and extracellular enzyme activity in the rhizosphere, bulk, and organic horizon of soils sampled from a long‐term (>25 years), whole‐watershed, N fertilization experiment at the Fernow Experimental Forest in West Virginia, USA. We observed significant declines in plant C investment to fine root biomass (24.7%), root morphology, and arbuscular mycorrhizal (AM) colonization (55.9%). Moreover, we found that declines in extracellular enzyme activity were significantly correlated with a shift in bacterial community composition, but not fungal community composition. This bacterial community shift was also correlated with reduced AM fungal colonization indicating that declines in plant investment belowground drive the response of bacterial community structure and function to N fertilization. Collectively, we find that enzyme activity responses to N fertilization are not solely driven by fungi, but instead reflect a whole ecosystem response, whereby declines in the strength of belowground C investment to gain N cascade through the soil environment.
Keywords:
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Ecology Nitrogen Fertilizers
Source:
Global Change Biology 24(6): 2721-2734, 2018
DOI:
https://doi.org/10.1111/gcb.14081
Pubmed Central ID:
29488286
Document Type:
Journal Article
Compliance:
PMC
Main Document Checksum:
[+]
urn:sha256:2f5924129d8a10312c34abd96cbaa495b7bbe5a5d7bdf3a5ffc88ad6be8a99ca
Download URL:
https://repository.library.noaa.gov/view/noaa/28627/noaa_28627_DS1.pdf
File Type:

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