Plant communities as a tool in temporary ponds conservation in SW Portugal

Abstract

Temporary ponds are seasonal wetlands annually subjected to extreme and unstable ecological conditions, neither truly aquatic nor truly terrestrial. This habitat and its flora have been poorly studied and documented because of the ephemeral character of the flora, the changeable annual weather that has a great effect on the small, herbaceous taxa and the declining abundance of temporary ponds. The objectives of this study are: (a) to define plant community diversity in terms of floristic composition of ephemeral wetlands in SW Portugal, (b) to identify temporary pond types according to their vegetation composition and (c) to identify those ponds that configure the European community priority habitat (3170* -Mediterranean temporary ponds).Vegetation sampling was conducted in 29 ponds, identifying 168 species grouped among 15 plant communities. Soil texture, pH, organic C and N content were measured, but only N and percent of clay appear to be related with the distribution of each community type. The results showed that ephemeral wetlands could be classified into four type: vernal pools, marshlands, deep ponds and disturbed wetlands. Vernal pools correspond to the Mediterranean temporary ponds (3170*), protected as priority habitat under the EU Habitats Directive. Submersed Isoetes species (Isoetes setaceum and Isoetes velatum) represents, together with Eryngium corniculatum, the indicator species for vernal pools. We identify also indicator plant communities of this priority habitat, namely I. setaceum and E. corniculatum-Baldellia ranunculoides plant communities. In this region, the conservation of temporary ponds has so far been compatible with traditional agricultural activities, but today these ponds are endangered by the intensification of agriculture and the loss of traditional land use practices and by the development of tourism.

Sensitivity of ephemeral wetland swards with Isoetes histrix Bory to environmental variables: implications for the conservation of Mediterranean temporary ponds

“…A high floristic richness was reported in other Mediterranean areas with similar habitat types, e.g. Portugal (168 species in 29 ponds, Pinto‐Cruz et al , ), and Morocco (253 species in 48 ponds, Rhazi et al , ). Under conditions of increased water availability, where submerged and floating macrophytes were observed, Díaz‐Paniagua et al () reported a lower floristic richness with 55 plant species in 21 temporary ponds at Doñana National Park, Spain.…”

“…The habitat is characterized as follows: oligotrophic waters containing very few minerals, generally on sandy soils of the West Mediterranean, with Isoetes spp., which is characteristic of very shallow water (few centimetres) with a flooding period not longer than 2–3 months (European Commission, ). These hydrological conditions have been described for the shoreline of temporary ponds, with a typical concave basin morphology, which determines the small‐scale zonation of the vegetation, and for the entire pond surface of shallow temporary ponds with a flat morphology (Biondi and Bagella, ; Molina, ; Rudner, ; Paradis et al , ; Pinto‐Cruz et al , ; Bagella et al , ). The conservation value of Isoetion was pointed out nearly a century ago (Allorge, ; Braun‐Blanquet, ), and European legislation has recognized that it serves a key role in biodiversity conservation (Council of the European Communities, ; Bagella et al , ).…”

“…Plant species assemblage structure and composition in temporary ponds provide a valuable tool for establishing habitat conservation priorities and strategies (Pinto‐Cruz et al , ). Consequently, the results of this study will provide guidelines for management of this threatened freshwater environment applicable at a local as well as global scale.…”

Assessing the conservation status of Mediterranean temporary ponds using biodiversity: a new tool for practitioners

“…We assessed conservation status of each pond using well-defined criteria selected from a comprehensive review of the literature (Grillas et al, 2004;Sala et al, 2004;Dimitriou et al, 2006;Fennessy et al, 2007;Stamati et al, 2008;Maes, 2013). This information was integrated and adapted using knowledge on the habitat and the region (Pinto-Cruz et al, 2009. Hence, the conservation status of each pond was assessed considering four parameters: (i) Topography-which is closely linked to the adequate hydroperiod, characterised by the timing and length of flooding, and water column depth; changes in hydroperiod have important effects in temporary waters, as they may change the pattern and strength of biotic interactions (Zacharias & Zamparas, 2010); (ii) Vegetation structure-a key parameter related to the habitat definition and presence of an ecological gradient, assessed by the number of vegetation belts.…”

“…Hence, the conservation status of each pond was assessed considering four parameters: (i) Topography-which is closely linked to the adequate hydroperiod, characterised by the timing and length of flooding, and water column depth; changes in hydroperiod have important effects in temporary waters, as they may change the pattern and strength of biotic interactions (Zacharias & Zamparas, 2010); (ii) Vegetation structure-a key parameter related to the habitat definition and presence of an ecological gradient, assessed by the number of vegetation belts. In this region, a well-preserved pond has three different vegetation belts (Pinto-Cruz et al, 2009); (iii) Impact of human activities-overall impact of the common anthropogenic activity on the condition of ponds (overgrazing, excavation, agriculture, hydrologic disturbance and tourism). The magnitude of a given disturbance is often more significant than the type of disturbance (Kantrud et al, 1989); and (iv) Trend of the pond area-the most important habitat feature for the conservation of a pond; if the pond area is stable or declining and in that case at which rate.…”