18.6.2012: Forschung CH

Die Regenwurmfauna der Auenwälder

Les vers de terre des forêts alluviales


Salomé Clémence et al.; Bullinger-Weber Géraldine et al.

Obwohl Regenwürmer wichtige Ökosystemingenieure sind, gibt es nur wenige Untersuchungen zu dieser Organismengruppe in Auenwäldern von der kollinen bis zur alpinen Stufe. Bei einer Studie in Schweizer Auenwäldern wurden 27 Arten und Unterarten identifiziert, das entspricht 2/3 der einheimischen Artenvielfalt in dieser Organismengruppe. Die Zusammensetzung der Regenwurmgesellschaften wird beeinflusst durch die Korngrössenverteilung des Bodens, aber auch durch die Höhenlage und die Vegetationssukzessionen. Epigäische (oberflächenliebende) Arten hängen stark von der Zusammensetzung der oberen Bodenschichten und deren Dynamik ab, und sind deshalb Indikatoren für vergangene Überschwemmungsereignisse.

Bien que les vers de terre soient d’importants ingénieurs des écosystèmes, il n’existe que peu d’études sur ce groupe d’organismes dans les forêts alluviales de l’étage collinéen à alpin. Au cours d’une étude réalisée dans des forêts alluviales suisses, 27 espèces et sous-espèces ont été identifiées, c’est-à-dire 2/3 de la diversité indigène de ce groupe d'organismes. La composition des communautés de vers de terre diffère selon la texture du sol, mais aussi selon l'altitude et les successions végétales. Les vers épigés (en surface du sol) sont sensibles à la composition des horizons de surface et à leur dynamique, et sont par conséquent des bioindicateurs des récents événements de crues.


Earthworms modify their environment by changing the distribution of materials and energy transfer in soil food webs that consequently induce the creation and/or destruction of habitats dedicated to subordinate species. In many terrestrial ecosystems, earthworms are considered as major ecosystem engineers. Through bioturbation, such as burrowing, casting and mixing of organic material and mineral particles, earthworms influence both soil physical (soil structure, water infiltration) and biological properties (organic matter decay, microbial activities). In turn, in many terrestrial ecosystems, soil parameters usually regulate the distribution of earthworm communities.
In alluvial ecosystems, few studies have investigated the impact of periodic floods and alluvium deposition on soil fauna. In this context, we assumed that earthworm communities may vary depending on altitude (alpine, subalpine, mountain and hill levels), forest successional stage (postpioneer to mature forests) and some soil parameters.
Our results demonstrated that the composition of earthworm communities differed depending on altitudinal gradients. No earthworm was found at the alpine level while maximum density and biomass were observed at the hill level mainly due to the contribution of anecic species. The absence of anecics was considered, at the subalpine level, as a bioindication of the fluvial dynamics (erosion and sedimentation processes).
A total of 27 species and subspecies were found over the three sampling sites, and Lumbricus moliboeus was discovered for the first time in carbonated soils. Soil texture had a major effect on epigeics that were often associated with coarse sandy texture in contrast to anecics which preferred deep soils and mature forest stages, which in combination provided the highest carbon content and the finest soil texture.
We conclude that in alluvial ecosystems, earthworm communities were highly dependent first on soil parameters, then altitude and to a lesser extent forest successional stages. Changes in earthworm communities tend to reflect a gradient of alluvial dynamics, especially latest flood events at the subalpine level, reinforcing the potential role of earthworms as bioindicators in natural and/or seminatural alluvial ecosystems.


Keywords:
vers de terre; zones alluviales; forêts alluviales; sols;

Art der Publikation:
Fachpublikation

Literatur:
Salomé C. et al. (2011). Earthworm communities in alluvial forests: influence of altitude, vegetation stages and soil parameters. Pedobiologia 54: 89-98.

Bullinger-Weber G. (2011). Impact of flood deposits on earthworm communities in alder forests from a subalpine floodplain (Kandersteg, Switzerland). European Journal of Soil Biology (accepted).

http://www2.unine.ch/lsv/page-5809.html



Kontaktadresse:
Dr. Claire le Bayon
Laboratoire Sol & Végétation Université de Neuchâtel
Rue Emile Argand 11
CH-2000 Neuchâtel

claire.lebayon@unine.ch
Tel: +41 (0)32 718 23 65


Zurück zur Liste