The proliferation of acacias in riverside areas threatens biodiversity and the functioning of aquatic ecosystems, confirmed research by the University of Coimbra (UC) carried out in the Lousã mountains.
“This study shows that biological invasions in a terrestrial ecosystem can have effects on adjacent ecosystems, such as streams, so it is important to consider the interdependence between ecosystems when assessing the effects of these invasions,” said researcher Verónica Ferreira, quoted in a UC press release sent to the Lusa news agency today.
As part of this study, the scientists carried out monthly sampling and measurements for a year “in six streams in the Serra da Lousã, an area heavily invaded by mimosa, three streams in native species forest and three streams in forest invaded by mimosa”.
According to the latest report by the Intergovernmental Platform on Biodiversity and Ecosystem Services, “invasion by alien species is a serious threat to biodiversity and the functioning of ecosystems”.
The Faculty of Science and Technology of the University of Coimbra (FCTUC) recalled that ‘acacia dealbata’, an exotic tree from Australia, known as mimosa, “is one of the main invasive species in the Central region of Portugal, especially in the Mondego river basin, where it already occupies significant areas”.
“The invasion of riverside forests by acacias affects the aquatic communities in the streams,” the FCTUC said in its statement.
The coordinator of the study, Verónica Ferreira, said that “the diversity of decomposer microorganisms and macroinvertebrates is lower in streams that cross acacias, compared to streams associated with native species forest, largely as a result of the lower diversity of plant debris that enters the streams in acacias and which is dominated by mimosa debris”.
“On the other hand, streams in native species forests receive a great diversity of plant detritus, as a result of the greater diversity of plants,” he added.
For the researcher from the Center for Marine and Environmental Sciences (MARE), “changes in the diversity of aquatic organisms in streams in invaded forest are worrying, since less diverse communities are less prepared to deal with environmental changes that may occur, such as those associated with climate change, and may be less effective at performing ecosystem functions, such as nutrient recycling.”
Faced with the difficulty of managing invasive species in riparian forests, Verónica Ferreira argued that “the best option is to protect riparian zones in the upper reaches of river basins, which are generally in a better state of conservation”.
Published in the journal Freshwater Biology, the study was carried out as part of the project “EXSTREAM – Effects of EXotic tree species on STREAM communities and processes: the case of invasion of native forests by Acacia spp.”, funded by the Foundation for Science and Technology.
The work was carried out in collaboration with professor and researcher Albano Figueiredo, from the Center for Geography and Spatial Planning Studies at the UC Faculty of Letters.
