Native and alien herbaceous plants in the Brazilian Cerrado are (co-)limited by different nutrients

Abstract

Background and aims: The diverse flora of the Brazilian Cerrado is threatened by agricultural expansion, nutrient enrichment and invasion of alien plants. We performed a fertilization experiment to investigate the nature of nutrient limitation in Cerrado vegetation, and evaluate whether native and alien invasive species are limited by the same or different nutrients. Methods: We applied various combinations of nutrients (phosphorus (P), nitrogen (N), and a mixture of other macro- and micro-nutrients (‘cations treatment’)) to six types of Cerrado vegetation. We then studied over a 3-year period how these treatments affected the aboveground biomass of native forbs, native C3 and C4 grasses, and invasive C4 grasses. Results: The full nutrient treatment (N + P+ ‘cations’) significantly increased total community biomass across our sites, but P alone had no effect. The nutrient treatments also affected the relative abundance of functional plant groups in the six vegetation types. P addition, either alone or in combination with other nutrients, increased the biomass of alien C4 grasses, where present, whereas the cations treatment stimulated growth of the native C4 grasses. Addition of N + P reduced the biomass of native C3 grasses. Conclusions: Our results indicate co-limitation by several nutrients, including P, perhaps N, and at least one other nutrient. Further research is needed to determine what the other nutrient (or nutrients) may be. Native and invasive species appear to be limited by different nutrients, with P alone stimulating growth of African C4 grasses. This should be considered in managing both natural and invaded communities.