Soil eutrophication induces distinct responses in Brazilian savanna’s tree species and affects ecological interactions

Abstract

Human-induced changes in global biogeochemical cycles, particularly in nitrogen (N) and phosphorus (P) flows, significantly impact plant growth and nutritional composition, thereby affecting ecosystem dynamics. However, research on effects of increased nutrient availability often focuses on primary producers community level effects, overlooking interspecific variability and neglecting impacts on higher trophic levels. Using a controlled fertilization experiment with six tree species native to Cerrado (Brazilian savannas) we showed that there is significant interspecific variation in how plant biomass responded to nutrient changes, indicating competitive advantages for certain native species under a scenario of soil eutrophication. We also show that such effects propagated to higher trophic levels (herbivores and their predators), also varying between plant host species. The strength and direction of N input effect of depended on P levels and the type of herbivores. Large invertebrate leaf-herbivores were less affected that phytophagous mites. Impacts on higher trophic levels (predatory mites) were less pronounced than on phytophagous mites. In summary, ongoing soil eutrophication has the potential to alter interspecific competition dynamics in plant communities with consequences for ecological interaction partners. These findings have important implications for conservation and ecosystem management, especially in areas highly exposed to soil eutrophication due to farming and industral activities.