Grazing as a management tool in dune grasslands: Evidence of soil and scale dependence of the effect of large herbivores on plant diversity

• Published in: Biological conservation 2008-06, Vol.141 (6), p.1687-1694
• Main Authors: Tahmasebi Kohyani, Pejman, Bossuyt, Beatrijs, Bonte, Dries, Hoffmann, Maurice
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Applied ecology; Autoecology; Beta diversity; Biological and medical sciences; cattle; coasts; Community structure; Conservation, protection and management of environment and wildlife; dunes; Fundamental and applied biological sciences. Psychology; grassland soils; grasslands; grazing; habitats; herbivores; Linear mixed model; Local scale; Nutrient availability; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; plant ecology; Plants and fungi; sheep; soil pH; species diversity
• ISSN: 0006-3207; 1873-2917
• DOI: 10.1016/j.biocon.2008.04.010

In nature management, the introduction of large herbivores into human-influenced grasslands is thought to be effective to maintain or enhance plant diversity. In order to test the validity of this assumption, we studied the effect of grazing by large herbivores on plant species richness and community heterogeneity across a soil acidity gradient at different spatial scales in dry coastal dune grasslands in western Belgium and north-western France. The effect of grazing on plant richness varied with scale and soil acidity. Grazing had a predominantly positive effect on plant species richness in all habitats at the small scale (0.25 × 0.25 m). However, at site scale (8 × 8 m) it had only positive effects in grasslands with higher soil pH (6–7.4). Similarly, grazing resulted in a homogenization of grassland vegetation at lower pH, while heterogeneity increased with grazing on soil with higher pH. In general, grazing increased the number of rare species, independent of soil pH. The results confirm that the impact of grazing on plant diversity depends on the scale considered and that the effects further depend on soil acidity which was correlated to biomass production at the given soil pH range in this study. Although grazing seems an appropriate management tool to maintain and even enhance plant biodiversity under many circumstances, it may negatively affect plant species richness, where soil resources limit plant biomass production.