Structural and Functional Shifts in Belowground Components Following Grass Invasion in a Tropical Savannah

ABSTRACT Questions Invasive African grasses threaten native plant communities and hinder ecological restoration in the Cerrado region, in Brazil. Their aboveground impacts are well described, but their belowground effects are less known. Because native species rely on bud‐bearing belowground organs for their persistence, changes in belowground components and structure can reveal hidden effects of the invader. Thus, we investigated whether the presence of an invasive African grass ( Urochloa brizantha ) affects Cerrado belowground components, both functionally by the proportion of fine roots and structurally by the abundance of different types of belowground organs. Location Cerrado open savannahs in southeastern Brazil (22°14′40′′S, 47°52′29′′W, 700 m a.s.l.). Methods We selected five invaded patches (minimum patch size = 10 m 2 ), which were individually paired with an adjacent non‐invaded patch as a control (totaling 10 patches). In every patch, we established 2 plots (0.25 × 0.25 m) to collect belowground organs until 0.3 m deep. Fine roots and soil were sampled beside each plot, every 10 cm until 1 m deep. Buds were counted, roots and belowground organs were oven‐dried and weighed, and soil nutrients were analyzed. We fitted generalized linear mixed models (GLMM) for each response variable to investigate the differences between invaded and non‐invaded patches. Results The belowground component of invaded areas was dominated by Urochloa brizantha 's fine roots and non‐woody rhizomes. The bud bank density was lower for all growth forms in invaded areas, except for the invaders' non‐woody rhizomes, pointing to changes in the system's regeneration capacity. Fine root biomass was higher in the upper layers of the soil in invaded areas, indicating higher space occupancy and faster nutrient cycling. Conclusions The belowground component of invaded areas is functionally and structurally different from non‐invaded areas, resulting in different plant community dynamics and resilience. Such differences could persist as legacy effects after the invader's removal.