Nitrogen and phosphorus enrichment effects on CO2 and methane fluxes from an upland ecosystem

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Type Article
Original languageEnglish
Pages (from-to)1199-1209
JournalScience of the Total Environment
Volume618
Early online date24 Sept 2017
DOI
Publication statusPublished - 15 Mar 2018
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Abstract

Reactive nitrogen (N) deposition can affect many ecosystem
processes, particularly in oligotrophic habitats, and is expected to
affect soil C storage potential through increases in microbial
decomposition rate as a consequence of greater N availability. Increased
N availability may also result in changes in the principal limitations on
ecosystem productivity. Phosphorus (P) limitation may constrain
productivity in instances of high N deposition, yet ecosystem responses
to P availability are poorly understood. This study investigated CO2 and
CH4 flux responses to N and P enrichment using both short- (1 year) and
long-term (16 year) nutrient addition experiments. We hypothesised that
the addition of either N or P will increase CO2 and CH4 fluxes, since
both plant production and microbial activity are likely to increase with
alleviation from nutrient limitation. This study demonstrated the
modification of C fluxes from N and P enrichment, with differing results
subject to the duration of nutrient addition. On average, relative to
control, the addition of N alone inhibited CO2 flux in the short-term (-
9%) but considerably increased CO2 emissions in the long-term (+35%),
reduced CH4 uptake in the short term (-90%) and reduced CH4 emission in
the long term (-94%). Phosphorus addition increased CO2 and CH4 emission
in the short term (+20% and +184% respectively), with diminishing effect
into the long term, suggesting microbial communities at these sites are P
limited. Whilst a full C exchange budget was not examined in the
experiment, the potential for soil C storage loss with long-term nutrient
enrichment is demonstrated and indicates that P addition, where P is a
limiting factor, may have an adverse influence on upland soil C content

Keywords

  • nitrogen deposition, soil carbon, carbon fluxes, pollution, co-limitation, P limitation