Moderate grazing intensity is considered the basic requirement to enhance ecosystem function in grasslands. Yet, deterioration by overgrazing is common in many biomes, including Campos grasslands in South America. Understanding how grazing management can lead to recovery of ecosystem function is essential to design and implement effective strategies for sustainable use of this resource. In a long‐term field experiment carried out in Southern Brazil, we studied the effects of temporal grazing exclusions (spring or fall) at moderate and severe livestock grazing intensities (maintained by adjusting contrasting forage allowances) on the species richness, botanical composition, forage mass, sward height, and photosynthetic active radiation intercepted. The experiment was arranged in a completely randomized design with three replications of grazing exclusions, applied simultaneously at moderate and severe grazing intensities. Moderate grazing intensity showed a bimodal structure of shorter and taller canopies, and high species richness. Severe grazing created a shorter and homogeneous sward structure characterized by less standing biomass and species loss. In response to grazing exclusions, sward height, standing biomass, and light interception recovered almost to the levels of moderate grazing. Further, within 2 years grass species richness increased and botanical composition changed toward grasses with erect habit prevailing in moderate grazing intensity. Our study confirms that (1) moderate grazing intensities allow the coexistence of high number of species and (2) spring grazing exclusions of long‐term overgrazed grasslands can lead to a quick start to recover the grass species richness, primary productivity, and species composition like that prevailing in well‐managed grasslands.

Questions: (i) How does a strategic deferment influence both shoot and root biomass in South American Campos natural grassland after a long time of contrasting livestock grazing intensities? (ii) How do functional strategies of plants to tolerate or avoid grazing affect patterns of aboveground and belowground biomass? Location: A natural Campos grassland in the Central Depression of Rio Grande do Sul State, Southern Brazil (latitude 30°05′27″ S, longitude 51°40′18″ W, and altitude 46 m). Methods: We studied the effects of deferments (spring or autumn) at moderate and severe livestock grazing intensities (maintained by adjusting contrasting forage allowances during 25 years) on the cover of dominant species, and aboveground and belowground biomass. The experiment was arranged in a completely randomized design with three replications of grazing exclusions, applied simultaneously at moderate and severe grazing intensities. Measurements of above-and belowground biomass and the coverage of the five dominant species were performed before and after grazing exclusion periods.Results: Under severe grazing intensity, erect-growing grasses were replaced by prostrate species, which were able at least to maintain the belowground biomass found at moderate grazing intensity. In response to deferments, severe grazing intensity changed toward a significant increase in aboveground biomass and in the coverage of plants with erect growing habit. However, total belowground biomass remained unaffected by exclusions in both grazing intensities. The relation of root:shoot biomass was lower under moderate grazing intensity, and showed a negative response to deferment treatments at severe grazing intensity. Conclusion: Long-term contrasting grazing intensities applied in South AmericanCampos grasslands determine several changes in above-and belowground relationships. Prevalence of prostrate plants under severe grazing is associated with a high partitioning capacity of assimilates toward the subterranean biomass, higher than in the tall species predominant under moderate grazing. The fast recovery of aboveground biomass, the maintenance of the underground biomass and the increase of tall 2 of 9 | Applied Vegetation Science FEDRIGO Et al.