European rabbit (Oryctolagus cuniculus) engineering effects promote plant heterogeneity in Mediterranean dehesa pastures

Mammalian herbivores can have dramatic effects on the vegetation through different mechanisms, and may therefore modify resource distribution or create habitat for other species. Organisms that cause such changes are classified as ecosystem engineers. The European rabbit (Oryctolagus cuniculus) is a semifossorial mammal native to the Iberian Peninsula and a keystone species in Mediterranean foodwebs. Rabbits are central-place foragers, but few studies have analysed their ecosystem engineering effects in the vicinity of warrens. Here, we explored the role of rabbits as ecosystem engineers in Mediterranean pastures in central Spain. We studied the spatial patterns and internal heterogeneity in the vegetation community of different spatial subunits created by rabbits (warrens, the warren influence area, and latrines). Within the different subunits, rabbit activities gave rise to patches and gradients with different plant species richness, diversity and height, and a high internal heterogeneity (dissimilarity) in floristic composition. Through different mechanisms, they have a significant effect on species coexistence and competitive interactions, and increase the number of available niches for plants which otherwise would not be able to establish. In conclusion, rabbits can act as allogenic ecosystem engineers in Mediterranean pastures, increasing heterogeneity and contributing to the high biodiversity of Mediterranean annual pastures.