Plant vegetative propagation plays a considerable role in the regeneration following slash-and-burn agriculture in Caatinga dry forest

Abstract

Slash-and-burn agriculture is a common practice in dry forests worldwide. Understanding the relative importance of different regeneration mechanisms following this disturbance provides insights into forest regeneration dynamics and resilience. We assessed differences in structural components, the relative contribution of vegetative and sexual reproduction, and the taxonomic composition of woody assemblages among different habitats in a Brazilian Caatinga dry forest after slash-and-burn agriculture. We assessed vegetation parameters (i.e., basal area, height, species richness, and the frequency of each regeneration mechanism) in recently abandoned fields, regenerating forest stands and old-growth forest stands. Overall, trees originates from root suckers accounted for at least 40% of the individuals, stems, and basal areas across the habitats. The structure of regenerating stands was similar to old-growth stands except for species composition, total number of roots, and number of primary roots. The aboveground basal area varied in total values, but not averages, among habitats, indicating a rapid recovery of aboveground biomass after slash-and-burn agriculture. Conversely, recently abandoned fields had higher belowground basal area and basal area of primary roots, revealing that the trees in these habitats emit more roots even with fewer individuals. There was a high degree of species turnover among the habitats, probably due to both species selection by farmers and environmental effects. Nevertheless, the dominant species presented both regeneration mechanisms across the habitats. Our findings thus show that the Caatinga dry forest regeneration considerably relies on the ability of woody plant species to emit root suckers in addition to sexual reproduction, which should be considered for better management practices as slash-and-burn agriculture is and will continue to be practiced.