Effect of inter-annual meteorological fluctuations and wild boar disturbance on the vegetation of Mediterranean temporary ponds

Questions: Which are the effects of inter-annual meteorological fluctuations on plant species richness and vegetation dynamics in Mediterranean temporary ponds, shallow wetlands characterized by alternating phases of drought and flooding? Which are the effects of wild boar disturbance? How do the responses of specialist or non-specialist species of the habitat differ?. Location: NW Sardinia Island (Italy). Methods: We assessed plant cover during six years within one 60 cm × 60 cm quadrat in each of five areas. To measure the effect of inter-annual meteorological fluctuations on vegetation, we used two indices: the evapotranspiration and the synthetic agrometeorological indicator. To quantify the effect of disturbance by boars, we compared two treatments: disturbed and non-disturbed (located outside and inside 1.5 m × 1.5 m exclosures respectively). As a whole, we monitored 60 plots (6 years × 2 treatments × 5 replications). We analyzed data using ANOVA, PERMANOVA and BIO-ENV. Results: Plant species richness and composition showed significant differences between years and treatments. Species composition was correlated with the evapotranspiration before the vegetative peak during the last period and with the agrometeorological indicator during the whole vegetative period. Specialist species showed much weaker growth, quantified as cover, in the drier years. Starting from the third survey year, plant richness and cover of specialist species were significantly higher in disturbed than in not-disturbed plots. The extent of bare soil generally was not affected by the treatment. Conclusions: Meteorological fluctuations affect plant species composition and vegetation dynamics in Mediterranean temporary ponds. The sensitivity of specialist species could make them particularly vulnerable to climate change. Nevertheless, they are resilient to unpredictable disturbances such as burrowing by wild boar. However, our results concerning the positive impact of wild boar disturbance on the vegetation cannot be generalized. Elsewhere, the lack of hunting activity could also be a problem for these habitats.