Human disturbances reduce tree abundance and stimulate woody plant resprouting and clonal growth in a tropical dry forest

In environments under chronic human disturbance, the persistence of woody plants via both resprouting of new shoots and clonal growth via new root suckers can increase survival and fitness. However, the relative frequency and importance of these mechanisms following disturbance remain poorly explored. Here we simulated both wood extraction (partial aboveground biomass (AGB) removal) and slash-and-burn (complete AGB removal plus burn) practices in situ and compare their effects versus controls after six months on the persistence (resprouting from new shoots and clonal growth via new root suckers), biomass, and structure (height, diameter at ground level, and number of stems) of six dominant tree species (n = 210). Tree regeneration following slash-and-burn varied from 0-80% across species. Half regenerated exclusively via clonal growth, one via resprouting, and one via both mechanisms. Increased disturbance intensity (control < wood extraction < slash-and-burn) resulted in at least fivefold more root suckers produced. Nevertheless, slash-and-burn led to the apparent mortality of nearly 70% of trees (i.e., absence of living aboveground tissue after six months). For those trees that did show evidence of regeneration, initial biomass recovery was nearly 5%, mainly from resprouting of new shoots. Our findings support the presence of persistence mechanisms after human disturbances in a relatively high proportion of woody plant species in the Caatinga dry forest. In the context of limited seed germination and seedling recruitment, resprouting and clonal growth may have a more significant role in regeneration dynamics than previously thought. Regeneration ability must be considered when choosing species for restoration purposes, especially in disturbed landscapes.