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| Titel |
Towards better understanding of the response of Sphagnum peatland to increased temperature and reduced precipitation in Central Europe |
| VerfasserIn |
Radoslaw Juszczak, Anna Basińska, Bogdan Chojnicki, Maciej Gąbka, Mathias Hoffmann, Damian Józefczyk, Mariusz Lamentowicz, Jacek Leśny, Dominika Łuców, Christophe Moni, Monika Reczuga, Mateusz Samson, Hanna Silvennoinen, Marcin Stróżecki, Marek Urbaniak, Małgorzata Zielińska, Janusz Olejnik |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250153815
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| Publikation (Nr.) |
 EGU/EGU2017-18838.pdf |
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| Zusammenfassung |
| With respect to climate change peatlands are highly vulnerable ecosystems. Especially a
potential drying in future might result in a major carbon source and release to the atmosphere.
We carried out a field climate manipulation experiment at Rzecin peatland in western Poland
to assess how increased temperature and reduced precipitation may impact carbon balance,
vegetation, microbes and water chemistry of the Sphagnum peatland. Here, we present results
of measurements conducted in two contrasting years (417 mm and 678 mm of precipitation in
very dry 2015 and wet 2016, respectively). The experimental design consists of four
treatments, each one replicated three times (control, CO; simulated warming, W; prolonged
drought, D and warming & drought, W+D). Increased temperatures (T) during the
year were achieved by infrared heaters (400W × 4 per site, approx. 60 W⋅m−2
addition of LW radiation). Precipitation was reduced using an automatic curtain,
covering the site during nighttime hours of the growth seasons. The manipulation
experiment was successful during both years, increasing the air (30 cm height) and soil
temperature (5 cm depth, sites W and D) by up to 0.2 oC and 1.0 oC, respectively.
Precipitation was reduced to 37 % during both years. At W+D site the peat temperature
was nearly two times higher than on W site indicating the impact of drought on T
increase.
To study the C exchange we developed an automatic mobile platform for measuring
CO2/CH4/H2O fluxes (LGR) as well as 13CO2 and 13CH4 fluxes (PICARRO CRDS
G2201-i). Measurements were performed, using dynamic ecosystem chambers (for
NEE and Reco) and combined with simultaneous measurements of surface spectral
properties. Flux calculation and gap filling was done according to Hoffmann et al.
2015.
Methane emissions were significantly higher on manipulated plots than on CO (25
gC⋅m−2yr−1) during both years, but only in the very dry 2015, CH4 fluxes were the highest
on W+D site
(33 gC gC⋅m−2yr−1). Besides temperature, methane emissions were positively
correlated with LAI of vascular plants, which was higher at the warmer sites during both
years.
Despite of being a net sink for CO2 during both years, the NEE was five times smaller for
all sites (-100 gC⋅m−2yr−1) during the dry 2015 year compared to 2016. The highest CO2
emissions were measured for the site with increased temperature (W site, Reco 780
gC⋅m−2yr−1). Temperature increase also provoked the productivity - GPP was
the highest at W site. While the smallest CO2 emissions and GPP were recorded
on the site exposed to reduced precipitation. This emphasizes the importance of
drought in inhibiting respiration and carbon uptake by plants. Despite of a higher
productivity, NEE was smaller on W and W+D, due to higher CO2 effluxes. As a result
of the drier conditions in 2015, the GWP of all sites was positive, showing the
highest values for the temperature increased sites. Compared to that, GWP was
negative for all sites besides those exposed to drought during the more wet year
2016.
Different vegetation parameters further support the C exchange estimates. In general,
warmer and drier conditions led to an increased LAI, whilst the site only exposed to drought
exhibited the lowest NDVI. In addition, increased temperatures shifted the vegetation species
composition by promoting vascular plants (mainly Carex rostrata and C. limosa), which
correlates positively with nutrient (Ptot, Mn, F, Na, Zn) availability in the ground
water.
We report short-term responses of peatland to increased temperature and reduced
precipitation, showing that the combination of these to stressors are leading to very different
scenarios, regardless of their individual impacts. Thus our results emphasize the need for long
term records from full-factorial field manipulation sites on peatland response to climate
changes.
The Research was co-founded by the Polish National Centre for Research and
Development within the Polish-Norwegian Research Programme within the WETMAN
project (Central European Wetland Ecosystem Feedbacks to Changing Climate – Field
Scale Manipulation, Project ID: 203258, contract No. Pol-Nor/203258/31/2013
(www.wetman.pl). |
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