Ana Lumbreras

Aquatic Ranunculus communities in the northern hemisphere: A global review

Abstract This study offers a general review of aquatic ranunculi communities in the northern hemisphere, and includes aspects of their ecology, syntaxonomy and distribution. White-flowered ranunculi communities (Ranunculus subgenus Batrachium) grow in a wide range of habitats, including different types of water regime (still and flowing waters; permanent and seasonal waters) and nutrient states. They are mainly found in Eurasia. High richness is detected in Western Europe and the Mediterranean area of heterophyllous and laminar-leaved species, and in Asia of species with only dissected leaves. The western centre of the heterophyllous species has been related to waters with low mineralization and oscillation events occurring between the Mediterranean and Temperate climates. Yellow-flowered ranunculi communities (R. Xanthobatrachium) include heterophyllous species with a tendency to helophytism. They also are found in a wide range of aquatic habitats. There is an uneven degree of knowledge on the ecology of aquatic ranunculi communities, and further research is required into aquatic ranunculi habitats in Asia and North America.

Habitat Variation in Vernal Pool Ecosystems on Both Sides of the Strait of Gibraltar

Abstract Lumbreras, A.; Tahiri, H.; Pinto-Cruz, C.; Pardo, C., and Molina, J.A., 2012. Habitat variation in vernal pool ecosystems on both sides of the Strait of Gibraltar. We studied vernal pool (VP) ecosystems along a latitudinal gradient crossing the Strait of Gibraltar in order to determine its role in the distribution of VP plant communities. We analyzed flora, vegetation, physical–chemical water parameters, and climatic data from two vernal pool areas on both the European (Iberian) and African (Moroccan) sides of the Strait. Despite the minor distance between both territories, the pools clearly differed in species composition and ecology. However, they showed a similar vegetation zonation in growth forms, including isoetid, batrachiid, and helophytic vegetation. The distribution of the plant communities was related to nutrient load, temperature, and precipitation. Water nitrate concentration was higher in Morocco, where VPs are characterized by Isoetes velata subsp. adspersa and Ranunculus saniculifolius communities. Iberian VPs had lower water nitrate content, and were characterized by Isoetes velata subsp. velata and Ranunculus peltatus communities. We think this nutrient difference is likely to be caused by the different land management regime on each side of the Strait, with more intensive agriculture in Morocco. Long-term (historical) and present-day (ecological) processes have been proposed to account for the habitat variation in vernal pool ecosystems on both sides of the Strait of Gibraltar.

Plant communities as a tool for setting priorities in biodiversity conservation: a novel approach to Iberian aquatic vegetation

Although conservation efforts are traditionally based on species red lists or similar documents, recent initiatives are starting to shift this scope to include other biodiversity structures and biological classifications. Plant communities have been indicated as being among the most promising categories for setting conservation priorities but their importance and potential is still underestimated. In this study we develop a conservation priority list based on aquatic plant communities of the Iberian Peninsula. Four criteria were used to perform a cumulative point-scoring ranking: regional responsibility, local rarity, wealth of its endangered flora, and habitat vulnerability. Our ranking constitutes the first comprehensive classification of aquatic vegetation in relation to its conservation priorities in Southern Europe. It reveals that amphibious communities are the most important vegetation target for conservation in Iberia related to oligotrophic environments with a bioclimatic Atlantic distribution. Plant communities characteristic of eutrophic waters or widely distributed were found to be cause for less concern when setting conservation priorities. Our results bring to light various discrepancies and gaps in current conservation laws affecting the Iberian Peninsula. Our study highlights the potential of plant communities in biodiversity conservation as they provide valuable information of habitat singularity, and supports that neither the sole use of species nor large scale approaches unaware of regional singularities are appropriate in setting conservation priorities.

Small-scale Isoetes distribution pattern in a Mediterranean vernal pool system

Abstract This work identifies plant-communities, specifically their Isoetes species composition, and analyses their spatial patterns in a Mediterranean vernal pool system located in central Spain. The vegetation zonation includes three bands of plant—community types and three ecotones from these, in a gradient leading from edge to bottom, with increasing length of flooding period. The intermediate plant—community type included the most interesting phytogeographical element in Ranunculus longipes and Isoetes setacea. This work highlights the important role that ephemeral Isoetes species can play in Mediterranean VP systems in characterising plant—community types. The three studied Isoetes species (I. velata, I. setacea and I. histrix) show a distribution in overlapped bands related with the period of flooding.

Dispersal mode and spatial extent influence distance-decay patterns in pond metacommunities

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.

Towards an ecological classification of flooded savannas in Beni (Bolivia)

Abstract Two main types of flooded savannas are identified in Beni, one of the most extensive areas of flooded savannas in the Neotropics: the floodable savannas of the bajíos and the floodable savannas of the semi-uplands. Independent classification methods done for both floristic inventories and soil sampling show a strong relationship between the content and availability of exchangeable bases in the soils and floristic composition of the plant communities. The grassy savannas on mesotrophic substrates which are rich particularly in Mg and Ca are characterized floristically by Thevetia amazónica and Acroceras zizanioides. On base—poor substrates, the floodable grassy savannas, as well as the tajibo savanna, are best represented floristically by Andropogon bicornis and Coelorachis aurita. A CCA carried out on this type of savannas revealed a primary distribution pattern of the plant communities along an Fe gradient, which can also be explained as a gradient of the duration of the flooding period.