Changes in the plant composition associated to wetlands as a consequence of anthropogenic intervention.
Human activities have had a negative impact on terrestrial ecosystems, reducing biodiversity. There are few documented cases of diversity increases. In recent decades, the sector Grano de Oro in the terminal stretch of the Palmar River was altered by deforestation of the deciduous forests for cattle ranching, transforming it into uncultivated land and seasonal pastures. Subsequently, the land was poldered and flooded to improve the availability of fresh grass. However, the plots were invaded by aquatic plants competing with planted grasses and attracting many other species such as waterfowl, so the diversity of aquatic species began to increase. In order to document this process of change, a spatio-temporal study of the land use between the years 1986 and 2004 was undertaken, using remote sensors of the area. Additionally, a study of the aquatic plant communities between 2004 and 2008 was performed, through nine samples (of 10 sub-samples of 1 m2 each). The results show significant reductions in the forest vegetation cover, which was replaced by shrubs and bare soil. The numbers of aquatic plants was similar (about 45 species) in both samples, changing only the composition of species. Currently, to prevent colonization of invasive species, modules are being leveled and a drip system is being implemented so that the diversity of aquatic organisms is expected to fall again.