Stimuli to the soil seed bank reduce the prevalence of exotic grasses in Amazonian pastures

Estímulos ao banco de sementes do solo reduzem a predominância de gramíneas exóticas em pastagens amazônicas

The restoration of riparian forests degraded by pasture is essential for maintaining ecosystem services such as water regulation and biodiversity preservation. However, the dominance of exotic grasses in Amazonian pasture regions hinders the natural regeneration of native species. This study aimed to evaluate the effects of soil seed bank stimuli on the initial restoration of a riparian forest dominated by exotic grass pasture. Two treatments were tested: control (CT) and seed bank stimulation (SBS). In both treatments, the region was isolated to prevent cattle entry. SBS was subjected to glyphosate herbicide application and soil disturbance with a disc harrow. Vegetation surveys to assess natural regeneration were conducted at time intervals of 5, 11, 18, and 22 months after the starting point of the experiment. SBS favored the density and richness of regenerating herb, shrub, and tree species and reduced soil coverage under exotic grasses up to the 18^th month (34%) in relation to CT (80%). In the 22^nd month, the dominance of exotic grasses increased in SBS, although it remained lower than that observed in the control throughout the evaluated period. The results showed that stimulating the seed bank through soil harrowing could effectively promote the regeneration of native species in the Amazon, although continuous management is necessary to reduce exotic grass dominance and ensure the long-term restoration of riparian forests.

Index terms:
Secondary succession; natural regeneration; pioneer species