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| Titel |
Tree invasion effects on peat water storage capacity (La Guette peatland, France) |
| VerfasserIn |
Stephane Binet, Emelie Viel, Sébastien Gogo, Franck Le Moing, Fatima Laggoun-Defarge |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250111567
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| Publikation (Nr.) |
 EGU/EGU2015-11700.pdf |
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| Zusammenfassung |
| In peatlands, carbon fluxes are mainly controlled by peat water saturation state,
and this saturation state is an equilibrium between recharge/drainage fluxes and
the peat storage capacity. The invasion of Sphagnum peatlands by vascular plants
is a current problem in many peat-accumulating systems, raising the question of
the relationships between vegetation changes and water storage capacity of peat
horizons.
To investigate this question, the water storage capacity of the "La Guette" peatland (France),
invaded by Betula spp was monitored at the watershed scale since 2008 using a
water balance approach and was estimated during the 20th century using historical
photographs showing the drainage network and the land cover change. During this
period, the site clearly experienced a vegetation change as the site was treeless in
1944.
Two main results arise from this experimental device:
(1) In this disturbed peatland, tree consumption amplifies the summer drought and the
resulting water table drawdown allows an increase of air entrapment in the peat. Even if
runoff flows occurred after this drought, the water storage capacity is affected, with about
30% of air that remains trapped in the peat porosity 6 months after the drought period. The
effects of a single drought on peat water storage capacity are observed over more than a
single hydrological cycle, suggesting a possible cumulative effect of droughts decreasing the
peat water storage capacity.
(2) Tree invasion is found to drive the drainage network morphology. Hydrological model
calibrated for the study site suggested that the development of drainage network had reduced
the water storage capacity of the peatland. These observations evidenced a positive feedback
between vegetation dynamics and water storage capacity: tree invasion changes the drainage
network geometry that decreases the peat water storage capacity, which in return may favor
tree development.
These two results highlight that the peat water storage capacity is indirectly reduced by tree
invasion. |
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