Abandonment of traditional saltworks facilitates degradation of halophytic plant communities and Carpobrotus edulis invasion

Prepared by Rosa M. Chefaoui & Sergio Chozas

Invasion of Carpobrotus edulis on the dykes of abandoned saltworks in Ria Formosa, Portugal. Photo credit: Rosa M. Chefaoui.

In the “Anthropocene” era, in which most ecosystems have been altered by humans, half of the world’s wetlands have been lost. Nonetheless, in certain cases, the changes produced by humans have resulted in particular high nature value systems, such as saltworks (“salinas”). These human-made wetlands have led to cultural ecosystems composed by halophytic species that grow in soils of high salinity.

In Mediterranean countries, traditional salt exploitation has been practiced over centuries. However, in recent years, this traditional land use has declined, which caused changes in the adjacent halophytic communities and triggered an invasion by opportunistic plant species.

In this study, we explore how the abandonment of saltworks is impacting the adjacent plant communities of the Natural Park of Ria Formosa (Algarve, Portugal). We use field surveys, geographical information systems (GIS) and statistical analyses to estimate the expansion of Carpobrotus edulis, an invasive species in many coastal regions throughout the world. We also study variations in the composition of plant communities of saltworks affected to different degrees by land-use change.

We found that land-use change caused by the cessation of traditional salt extraction has led to more than a four-fold increase in the cover of C. edulis throughout the abandoned salinas over a decade. Our research has also shown that plant composition and C. edulis cover varied along a gradient of soil salinity and moisture in the studied saltworks. In general, the abandonment of saltworks facilitated a transition from halophytic species to plants which thrive in sandy conditions. Our results support the idea that maintenance of traditional saltworks activities is vital for the preservation of this fragile wetland ecosystem.

This is a plain language summary for the paper of Chefaoui & Chozas published in the Applied Vegetation Science (https://doi.org/10.1111/avsc.12436).