 |
| Titel |
Effects of experimental nitrogen deposition on peatland carbon pools and fluxes: a modelling analysis |
| VerfasserIn |
Y. Wu, C. Blodau, T. R. Moore, J. Bubier, S. Juutinen, T. Larmola |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 1 ; Nr. 12, no. 1 (2015-01-07), S.79-101 |
| Datensatznummer |
250117760
|
| Publikation (Nr.) |
 copernicus.org/bg-12-79-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| Nitrogen (N) pollution of peatlands alters their carbon (C) balances, yet
long-term effects and controls are poorly understood. We applied the model
PEATBOG to explore impacts of long-term nitrogen (N) fertilization on C
cycling in an ombrotrophic bog. Simulations of summer gross ecosystem
production (GEP), ecosystem respiration (ER) and net ecosystem exchange
(NEE) were evaluated against 8 years of observations and extrapolated for 80 years to identify potential effects of N fertilization and factors
influencing model behaviour. The model successfully simulated moss decline
and raised GEP, ER and NEE on fertilized plots. GEP was systematically
overestimated in the model compared to the field data due to factors that
can be related to differences in vegetation distribution (e.g. shrubs vs.
graminoid vegetation) and to high tolerance of vascular plants to N
deposition in the model. Model performance regarding the 8-year response of
GEP and NEE to N input was improved by introducing an N content threshold
shifting the response of photosynthetic capacity (GEPmax) to N content
in shrubs and graminoids from positive to negative at high N contents. Such
changes also eliminated the competitive advantages of vascular species and
led to resilience of mosses in the long-term. Regardless of the large
changes of C fluxes over the short-term, the simulated GEP, ER and NEE after
80 years depended on whether a graminoid- or shrub-dominated system evolved.
When the peatland remained shrub–Sphagnum-dominated, it shifted to a C source after
only 10 years of fertilization at 6.4 g N m−2 yr−1, whereas this
was not the case when it became graminoid-dominated. The modelling results
thus highlight the importance of ecosystem adaptation and reaction of plant
functional types to N deposition, when predicting the future C balance of
N-polluted cool temperate bogs. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|