How can Mediterranean temporary ponds benefit from disturbance? Challenges and lessons learned from vegetation management

Abstract

Mediterranean temporary ponds (MTPs) are seasonal wetland habitats usually flooded during the rainy season but drying out during the warmer months. Due to their biodiversity, uniqueness, and numerous threats, they are listed as a priority for conservation under the Habitats Directive. Despite all the efforts made so far, they are still in poor conservation status in the Mediterranean biogeographic region, making it urgent to define efficient conservation and restoration actions. In this work, we used two case studies to evaluate the conservation status improvement of MTPs located on the southwest coast of Portugal, following the implementation of different management techniques. Sampling was based on floristic surveys to assess plant richness and species frequency, namely of characteristic MTPs species. In the first case, we tested three management techniques (direct grazing, vegetation cutting, and biomass cut/removal, followed by topsoil plowing—simulating wild boar trampling and wallowing) in plots installed in three MTPs between 2017 and 2018. Plots subject to wild boar simulation disturbance showed higher species richness, higher frequency of characteristic species, and lower dominance of Agrostis stolonifera. In the second case, we upscaled this technique as an ecological restoration action by using it in 10 MTPs between 2018 and 2021. We observed a positive effect on the habitat's structure and conservation status, although the possible influence of recurrent drought periods in the last decade is discussed. This study provides insights into a rare wetland habitat based on lessons learned from hands-on conservation actions, while also identifying new challenges and knowledge gaps.