Grassland afforestation in South America: Local scale impacts of eucalyptus plantations on Uruguayan mammals

One of the main causes of global biodiversity loss is the change in land use and land cover, causing fragmentation and habitat loss. Uruguay has experienced a strong expansion of afforestation during the last two decades, at the expense of grasslands. In five afforested landscapes we installed camera traps following a stratified random sampling design covering grassland adjacent eucalyptus and firebreaks to evaluate the effects of grassland afforestation on the medium and large-sized mammal assemblage in Uruguay. We successfully recorded data in 111 sampling stations with a sampling effort of 9043 camera-nights. A total of 14 mammal species were registered, 11 native and 3 exotics. Our results show that grassland afforestation generates a negative impact at a local scale on the assemblage of medium and large-sized native mammals in the five study areas, reducing cumulative species richness and capture rate compared to grasslands. The generalist, omnivore, and insectivore species were the dominants and the only ones detected within the eucalyptus stands, while the grassland specialist in our study, Dasypus septemcinctus, was never registered in this environment. On the other hand, the evidence also shows that tree plantations are not green deserts, since 35% of the species were recorded on the stands, ascending to 70% if the species registered in firebreaks are added. Firebreaks, the linear structures of grasslands of 12 m-width designed by forestry planners to isolate afforestation stands to control fires, also plays a relevant role for mammal diversity in afforested landscapes of Uruguay, by connecting patches of native vegetation.

Automated summary

Grassland afforestation in Uruguay has a negative impact on the assemblage of native mammals, reducing species richness and capture rate. However, tree plantations are not green deserts, with 35% of species recorded within the stands, rising to 70% when including species in firebreaks.