 |
| Titel |
A black alder plantation improves the greenhouse gas balance of a degraded
moist peat grassland |
| VerfasserIn |
Sarah Bereswill, Mathias Hoffmann, Vytas Huth, Yulia Popova, Dominik Zak, Jürgen Augustin |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250149989
|
| Publikation (Nr.) |
 EGU/EGU2017-14405.pdf |
|
|
|
|
|
| Zusammenfassung |
| Drained peatlands are among the strongest terrestrial sources of the greenhouse gases (GHG)
CO2 and N2O. Therefore, activities of peatland revitalisation through rewetting, often
combined with the implementation of peat forming vegetation, aim to restore the GHG sink
function that is characteristic for pristine peatlands. Black alder (Alnus glutinosa) naturally
occurs in temperate marshes and minerotrophic peatlands (= fens) and is also suitable for
paludiculture, the cultivation of biomass on wet or rewetted peatlands. However, only little
information exists, if a black alder plantation can reduce the climate impact of restored
peatlands.
Therefore, we investigated the effect of a newly established black alder plantation on the
net GHG balance of a degraded fen in north-eastern Germany during a two-year study
(August 2010 – August 2012). We compared the alder plantation (Awet) with an extensively
used meadow (Mwet) both characterized by very moist soil conditions and a drier reference
meadow (Mdry) characterized by moderately moist soil conditions. CO2, CH4 and N2O
fluxes were measured monthly to bi-monthly with the manual closed chamber method. Fluxes
were calculated using a modular R script and gap filled to obtain continuous daily
fluxes.
Awet was a net GHG sink of -4.8 t CO2-eq ha−1 yr−1, Mwet was climate neutral
(-0.03 t CO2-eq ha−1 yr−1), and Mdry was a net GHG source of 15.7 t CO2-eq ha−1 yr−1.
This was mainly caused by CO2 uptake at the two very moist sites and a high CO2 release at
the drier reference site. In addition, Awet was a larger CO2 sink than Mwet, likely caused by
an additional CO2 uptake of the alder stand. All sites were significant CH4 sources. Due to
inundation following extraordinarily heavy precipitation in summer 2011 remarkable
CH4emission peaks were found on all sites which accounted for up to 70 % of the
cumulated two-year CH4emissions. However, overall Awet emitted significantly lesser
CH4(4.9 g C m−2 yr−1). We assume that the black alders decreased the CH4emissions due
to their effective O2 transport mechanism. N2O emissions were negligible at all three
sites.
Our results indicate that rewetting and planting black alders significantly improve the
GHG balances of formerly drained fens already in the first two years after plantation.
Furthermore, only one wet summer significantly increased the CH4 emissions of our study
site, despite two-year average groundwater levels (GWL) of -0.2 to -0.35 m. This highlights
the importance of acknowledging extreme precipitation events and groundwater fluctuations
for the derivation of reliable GHG emission factors. |
|
|
|
|
|
|