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| Titel |
Outstanding accumulation of \textit{Sphagnum palustre} in central-southern Italy |
| VerfasserIn |
Laura Casella, Claudio Zaccone |
| 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 |
250153953
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| Publikation (Nr.) |
 EGU/EGU2017-18992.pdf |
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| Zusammenfassung |
| Lake Fibreno is a site where some outstanding anomalies for the flora and vegetation of the
wetlands of peninsular Italy are concentrated. Here one the southernmost European
population of Sphagnum palustre occurs, and is restricted on the surface of a free-floating
island, i.e., a round-shaped portion of fen (with a core of Sphagnum), erratically floating on
the surface of a submerged sinkhole.
Geological evidences point out the existence in the area of a large lacustrine basin since
Late Pleistocene. The progressive filling of the lake, caused by changing in climatic
conditions and neotectonic events, resulted in the formation of peat deposits in the area,
following different depositional cycles in a swampy environment. So that, the studied
free-floating island, probably originated around lake margins in the waterlogged area, was
somehow isolated from the bank and started to float. Once the separation occurred, sedge peat
stopped to accumulate, thus enhancing the role of S. palustre as the main peat-forming
plant.
The vegetation occurring at the moment of the isolation of the island was a coverage of
Salix cinerea/Populus tremula stands below which cushions of moss and, in a lower extent,
Thelypteris palustris/Equisetum palustre accumulated resulting in the formation
of 2-3 meters of peat dominated by reeds and sedges. This vegetation has been
partially degraded by grazing until 1970s, while in 1980s the lake became a nature
reserve.
Since then, the succession could resume in a spontaneous and natural way and it was
possible for the vegetation to recover to natural dynamics and growing rate. The Sphagnum
tussocks were measured in an empirical way at a distance of about 60 years after the last
signaling and the result was a measurement of an accretion open to about 70 cm thick.
Moreover, in a recent study, a 4-m deep peat core was collected from the centre of the island
and results were surprising. In fact, 14C age dating, confirmed using 210Pb and 137Cs, showed
that the top 2 m of ombrotrophic Sphagnum-peat has accumulated in only ∼100 years
(growth rate: ∼2 cm/yr).
These values are extremely important in the evaluation scenario of the importance of
these habitats especially considering that the site is currently circumscribed in a
Sub-Mediterranean climate area (deciduous species-rich oak forests dominate the slopes of
the catchment, and Mediterranean evergreen woody species are scattered on topographical
discontinuities). |
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