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Assuming that dispersal modes or abilities can explain the different responses of organisms to geographic or environmental distances, the distance-decay relationship is a useful tool to evaluate the relative role of local environmental structuring versus regional control in community composition. Based on continuing the current theoretical framework on metacommunity dynamics and based on the predictive effect of distance on community similarity, we proposed a new framework that includes the effect of spatial extent. In addition, we tested the validity of our proposal by studying the community similarity among three biotic groups with different dispersal modes (macrofaunal active and passive dispersers and plants) from two pond networks, where one network had a small spatial extent, and the other network had an extent that was 4 times larger. Both pond networks have similar environmental variability. Overall, we found that environmental distance had larger effects than geographical distances in both pond networks. Moreover, our results suggested that species sorting is the main type of metacommunity dynamics shaping all biotic groups when the spatial extent is larger. In contrast, when the spatial extent is smaller, the observed distance-decay patterns suggested that different biotic groups were mainly governed by different metacommunity dynamics. While the distance-decay patterns of active dispersers better fit the trend that was expected when mass effects govern a metacommunity, passive dispersers showed a pattern that was expected when species sorting prevails. Finally, in the case of plants, it is difficult to associate their distance-decay patterns with one type of metacommunity dynamics., Competing Interests: The authors have declared that no competing interests exist.

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. [ABSTRACT FROM AUTHOR]

Abstract: Vascular flora of Mediterranean temporary pools has been studied with the aims to define its diversity and to individuate the ecological characteristics of the different plant groups associated with this relevant and endangered habitat type. Overall, 246 species were found of which 108 were terrestrial, 57 generalist of aquatic or wet habitats and 81 typical of temporary water and strongly linked to temporary pools. The results suggest that: (i) vascular flora associated with Sardinian Mediterranean temporary pools is rich and diversified; (ii) rare ferns are better represented than previously reported; (iii) plant species are generally heliophilous and acidophilous, specialized temporary pool species mainly differing from the unspecialized ones in relationship to their soil moisture requirements; (iv) these habitats are particularly important for maintaining regional freshwater biodiversity. [Copyright &y& Elsevier]

The current interest in Mediterranean temporary wet habitats, considered to be habitats of European Community Interest, is mainly due to their characteristic flora and fauna. Several contributions characterize each of these two components separately, but considering them simultaneously could reveal possible interactions and a more complete view of the habitat that would be useful to improve conservation measures. This paper investigates crustacean and plant assemblages in six Mediterranean temporary ponds and their relationship with several environmental variables. Significant positive relationships were found between species richness and Shannon diversity index of plant and crustacean assemblages. Crustaceans had a higher similarity among ponds than plants and, consequently, each pond had a more characteristic assemblage of plants than of crustaceans. The two groups showed a different sensitivity to environmental factors and only two factors affected both: altitude and surface area of the wet system. Disturbances (e.g. grazing by cattle) and pond size were very important for plants, whereas they were irrelevant for crustaceans. On the other hand, distance to the nearest pond, hydroperiod length, and water nitrogen were only important for crustaceans. Although similar trends on richness and diversity were observed for both biotic groups, the use of only one of them for conservation programs would not be sufficient. Our results suggest that simultaneously taking into account several community components would result in a better understanding of ecosystem functionality. [ABSTRACT FROM AUTHOR]