European rabbit (Oryctolagus cuniculus) engineering effects in the summit vegetation on the Island of Tenerife

Abstract

The European rabbit, Oryctolagus cunniculus, may dramatically affect the vegetation through different mechanisms, and therefore may contribute to modify habitat and communities, producing benefits in some species and harming others. Thus, rabbit might be considered as a landscape engineer. The European rabbit is an invasive mammal in the Canary Islands, and a keystone species in the change of the ecosystems. Some studies have shown the effects of this herbivore on some threatened species, but they do not have analysed its wide scale effects on dominant species of the Canary ecosystems. Here, we have explored the role of rabbits as ecosystem engineers in the summit vegetation of the Canary Islands, through a study on the population structure of Spartocytisus supranubius and Pterocephalus lassiospermus. We have studied the spatial heterogeneity of these two dominant species and the relationship between rabbit density and age-classes. For this purpose 90 analysis plots were established along 30 localities, within the distributional area of S. supranubius. Furthermore, we used 12 permanent plots of herbivore exclusion controlled by Teide National Park. In all of them the structure and composition of vegetation, as well as the most important abiotic variables, were analyzed. This study showed that density of rabbits is the most influential variable on the population structure of S. supranubius. It also confirmed that the population of the broom scrub is declining due to the negative effect of rabbits in its regeneration and showed that the decline of S. supranubius was positively correlated with the increase of P. lasiospermus.