On March 24th, the students of the subject “Ecology of Global Change: Current Transition of the Biosphere” visited the Guadiamar River basin. The subject belongs to the Biology degree of the University of Seville (US).
The objective of the excursion was to carry out an ecological and environmental analysis of the landscape and ecosystem transformations produced by the anthropic action during centuries in the outskirts of the city of Seville. The Guadiamar River, because of its ancestral importance as a source of water and resources, is a good example of these transformations that can be observed from its birth in the Sierra Norte until its mouth in the Guadalquivir River, in the marshes of the Doñana Park.
The professors María Cruz Díaz Antúnez-Barradas (US) and María José Leiva Morales (US) described the different ecosystems where the Guadiamar River flows. In its high part, in the mountain range, the Guadiamar River crosses forests and plantations of eucalyptus trees. In the middle section, the amplitude of the fluvial valley appears increasing riverside vegetation in the borders and meadows in the high zones. Further down, the river enters the Protected Landscape of the Guadiamar Green Corridor where the forest of the alluvial plains was reforested with Mediterranean shrubs and trees (oaks, olive trees, brooms, etc.), while the forest gallery shows poplars, ash trees and willows. Finally, in the low section, it ends in the marshes of Doñana, where crops of rice and brackish pastures appear.
At the Doblas stop (Sanlúcar la Mayor), Marta Gil Martínez (IRNAS-CSIC) was invited to talk about the consequences and restoration measures after the Aznalcóllar mine spill to the Guadiamar River, as well as the results of the investigations which is carried out by IRNAS-CSIC researchers in the Green Corridor (RECARE and RESTECO projects). Soil contamination by heavy metals, such as lead, zinc, cadmium and copper, affects the growth and health of plants, soil organisms and, in general, the ecosystem food web. Soil-plant-microorganism interaction is being investigated in soils with different levels of contamination. The ability of plants and their associated microbes to stabilize heavy metals in the soil (a technique known as phytostabilization) and thus reduce the risk of toxicity in the ecosystem is studied.