Influence of land use on the composition of plant communities from seasonal pond ecosystems in the Guadiana Valley Natural Park (Portugal)
Santo, Dalila Espírito; Arsénio, Pedro
The aim of this work is to study the relationship between land use and different seasonal pond communities, as well as their spatial and temporal distribution in the Guadiana Valley Natural Park (Mediterranean Iberian Peninsula). A total of 104 relevés were undertaken according to the method of Braun-Blanquet (1979). The relationships between species and environmental variables were studied through a canonical correlation analysis (CCA) applied to these relevés using the CANOCO program. A classification with the TWINSPAN program (Hill 1979) was also made. Ten groups corresponding to the following associations were recognized: Callitricho brutiae-Ranunculetum peltati, Bolboschoenetum maritimi, Glycerio declinatae-Eleocharitetum palustris, Eryngio corniculati-Preslietum cervinae, Peplido erectae-Agrostietum salmanticae, Isoeto velatae-Juncetum pygmaei, Pulicario uliginosae-Agrostietum salmanticae, Periballio laevis-Illecebretum verticillati, Loto subbiflori-Chaetopogonetum fasciculati and Trifolio resupinati-Caricetum chaetophyllae. Both flooding period and land use were found to determine the occurrence of each of these communities. Grazing can favour the occurrence of Isoetes spp. communities. Soil mobilization from agricultural activities, on the other hand, is often related to the disappearance of these communities because in such circumstances no surface water accumulation occurs.