Species diversity influences water availability and nutrient-related strategies in native and exotic Cerrado plants

ABSTRACT Acid phosphatase activity in roots and root association with mycorrhizal fungi enhance nutrient extraction from the soil. However, environmental changes, such as drought and biodiversity loss, can significantly influence these mechanisms. In this study, we investigated how water availability in pots, with varying numbers of species, influences acid phosphatase activity and mycorrhizal colonization. We conducted an experiment in a greenhouse with three herbaceous species found in the Cerrado biome: Melinis repens (a naturalized grass), Urochloa decumbens (an invasive exotic grass), and Calopogonium mucunoides (a native legume). The experiment followed a completely randomized design, using a replacement-series approach, with a constant plant density per pot and variation in species composition and richness. We determined total biomass, root acid phosphatase activity, and mycorrhizal colonization in monocultures and combinations of two and three species. Our results highlight that: (1) as biodiversity increases, there is a decrease in water mass, indicating the effect of niche complementarity on water use; (2) water depletion positively affects root acid phosphatase activity, suggesting that severe droughts may disrupt the phosphorus cycle; (3) biodiversity promotes an increase in mycorrhizal colonization across all three species, indicating the importance of species diversity in supporting mycorrhizal associations; (4) the naturalized grass Melinis repens utilizes alternative strategies for nutrient acquisition, evidencing its phenotypic plasticity; (5) the highly invasive grass Urochloa decumbens benefits from higher biodiversity, showing increased mycorrhizal colonization, and invests acid phosphatase production into biomass. These results are essential for understanding the impacts of biodiversity on water availability and biological invasions in the Cerrado.