In general, and for an untrained observer, plants of Mediterranean Temporary Ponds do not seem to be very important nor do they look very flashy. However, nothing could be further away from the truth: they are numerous, very special, and in some cases have high conservation value.
Photos of Cristina Madeira Baião, José Pacheco, Nuno Pedroso, Vasco Flores Cruz e Carla Pinto Cruz.
Photos of José Pacheco, Vasco Flores Cruz, Bruno H. Martins, Elisabete Rodrigues, Liliana Barosa, Nuno Pedroso, Paula Canha, Ricardo Pita, Francisco Amorim, Helena Santos e Ana Rainho
Mediterranean Temporary Ponds are colonized by communities of vascular plants, which mostly consist of small herbaceous plants. The peculiarity of the characteristic species of these ecosystems comes from their degree of specialization, and from the different adaptive mechanisms developed in order to tolerate and survive under extreme ecological conditions of draught and submersion. It is precisely this hydrological dynamic - the existence of a cyclical flooding period - that hinders the non-characteristic plants from colonizing this habitat. For example, it prevents the establishment of land species. On the other hand, the dry period hinders the establishment of aquatic plants that require almost permanent water to survive.
The different plants may be grouped according to the different biological strategies, specific for each time of the year. In the beginning of spring, fluctuating water plants with the leaves and flowers on the water surface are abundant in the pond. The amphibious plants begin their development underwater and bloom only when the pond begins to dry, thus persisting until the onset of the dry season. It is also common to find small annual plants that reproduce each year by seeds, which lie dormant in the soil waiting for the arrival of Spring.
Besides this temporal dynamics, there is also a zonation of plant communities along the spatial gradient from the centre to the borderline of the ponds. These communities are organized according to homogeneous floristic belts, and in accordance with a gradient of water availability.
In Southwest Portugal several plant species with high conservation value are associated to the Mediterranean temporary ponds. Some examples are the Pilularia minuta, (IUCN red list- “Threatened”), Isoetes setaceum (IUCN red list - “Near threatened”), Caropsis verticillo-inundata (IUCN red list - “Vulnerable”), and Hyacintoides vicentina (annexes II and IV from the Habitats Directive).
Pilularia minuta - Photo of Carla Pinto Cruz
Isoetes setaceum - Photo of Carla Pinto Cruz
Caropsis verticillo-inundata - Photo of Carla Pinto Cruz
Hyacintoides vicentina - Photo of Carla Pinto Cruz