- 1Institut
Méditerranéen de Biodiversité et Ecologie, UMR CNRS-IRD, Avignon
Université, Aix-Marseille Université, IUT d'Avignon, 337 chemin des
Meinajariés, Site Agroparc BP 61207, 84911, Avignon Cedex 09, France.
- 2Institut de Recherche de la Tour du Valat, Le Sambuc, 13200, Arles, France.
- 3Institut
Méditerranéen de Biodiversité et Ecologie, UMR CNRS-IRD, Avignon
Université, Aix-Marseille Université, IUT d'Avignon, 337 chemin des
Meinajariés, Site Agroparc BP 61207, 84911, Avignon Cedex 09, France. thierry.dutoit@imbe.fr.
Abstract
Extensive
grazing by domestic herbivores is a widespread management practice used
since the 80s in many European agro-ecosystems such as semi-natural
grasslands to maintain open habitats and to enhance biodiversity. Such
grazing systems have principally been tested in cultural ecosystems of
high nature value threatened by grazing abandonment. However, there have
been few case studies of grazing management in very anthropized
ecosystems, such as the new ecosystems created by urban or industrial
conversions. In Southern France,
the Rhône channeling for navigation and electricity production
generated in the 1950s the construction of thousands of hectares of dams
and dykes which were colonized naturally by diverse plant communities.
Yet shrub encroachment and the consequent recourse to mechanical cutting
to facilitate control and maintenance, raise the question of how best
to maintain and manage these new habitats. Consequently, since 1999,
different low-intensity grazing management systems using rustic breeds
of cattle, horses and goats
have been tested on a protected reserve of 1454 ha located in the lower
part of the Rhône river. Extensive grazing, more than cutting or no
management, positively modified vegetation heterogeneity
(beta-diversity), the target open grassland species, but not plant
species richness (alpha-diversity). However, the current monitoring
shows that these benefits of grazing will be confirmed only if
low-intensity grazing systems are sustained and if new adaptations can
be also made, such as the use of mixed stocking and the establishment of
multiyear contracts with breeders.
KEYWORDS:
Adaptive management; Alpha-diversity; Anthropized ecosystems; Beta-diversity; Extensive grazing
