Nitrogen cycle
Nitrogen deposition is slowing forest respiration
Open access · cc by · source: Europe PMC
At Loobos, TER fell while GPP rose over 26 years; acid soils (pH 2.9) and N deposition appear to throttle decomposition.
How this study connects
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At Loobos, TER fell while GPP rose over 26 years; acid soils (pH 2.9) and N deposition appear to throttle decomposition.
Evidence for the claim as stated.
Study at a glance
- Design
- Other — 26-year eddy-covariance record with soil incubations testing pH and substrate limits
- N
- N=1 · Loobos Scots pine FLUXNET site, 1997–2021, plus laboratory incubations of acidic topsoil
- Population
- Dutch Scots pine forest under chronic nitrogen deposition
- Outcome
- Total ecosystem respiration fell while GPP rose; acid soils (pH 2.9) and N deposition appear to throttle decomposition
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Inspect source passages
Nitrogen deposition is slowing forest respiration
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
Soil respiration averages 69% of TER
TER is composed of an average of 69% soil respiration and 31%
What unexplained trend did Loobos show?
we are the first to combine an assessment of the long‐term negative TER trend with soil respiration experiments in a forested ecosystem flux site exposed to severe nitrogen deposition.
Key findings
TER fell from 1350 to 1015 g C m−2 year−1 (1997–2021) while GPP rose from 1567 to 1904. Soil respiration is ~69% of TER. The organic layer doubled in mass (about 4.7 to 9.4 kg C m−2). R10 declined (36% implied TER drop); soil warmed 1.25°C. Incubations showed an active but pH-inhibited microbiome (pH 2.9). N deposition was 38 kg N ha−1 year−1 in 1990 and 21 in 2023.
Methodology
Authors analyzed 1997–2021 eddy-covariance fluxes at the Loobos Scots pine site in the Netherlands, compared other long FLUXNET forests, inventoried the organic layer, and incubated acidic topsoil with glucose and lime to test substrate and pH limits on CO2 release.
Limitations
A second, taller tower after 2021 raised TER estimates, so some instrumental contribution cannot be ruled out. 2024 C and N analyses were incomplete. There is no continuous soil-pH time series. NEE sustainability remains an open ecosystem-health question.
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