Assessing effectiveness of exclusion fences in protecting threatened plants

Abstract Overgrazing stands out as threat factors on biodiversity, being especially harmful in the Mediterranean, due to strong human pressure and an accelerated climate change acting synergistically. Fencing is a common tool used conservation biology tackle this problem. Advantages of fences are usually fast, intuitive, easy evaluate. However, disadvantages could also arise (increasing interspecific competition, disturbing habitat structure, limiting pollination, reducing dispersion). Together with management issues (maintenance, conflicts stakeholders, pulling effect). Effectiveness fencing for has been frequently assessed animals, while it almost neglected topic plants. We evaluated outcome three threatened narrow-endemic Selected 5 populations were only partly fenced, which allowed comparing different variables inside outside fence. For evaluating effects, we sampled several habitats (vegetation cover, composition, density target species), target-species features (individual size, neighbouring species, fruit-set). had effects individuals, showing contrasting responses at species population level. Particularly, Erodium cazorlanum , fence positive effect one case, negative another. In Hormathophylla baetica was all populations. Finally, negatively affected Solenanthus reverchonii by increasing competition seed-dispersal. highlighting need case-by-case evaluation determine net balance (pros vs. cons), its suitability most favourable option (i.e. permanent temporary fences).