Coppicing as a driver of plant resprouting and the regeneration of a Caatinga dry forest

Abstract

Resprouting is a widespread mechanism through which woody plants recover from biomass loss and/or abiotic stress, particularly in fire-prone ecosystems. Here, we assess the resprouting responses to coppicing exhibited by woody plant species in a human-modified landscape of Caatinga dry forest, in the northeast of Brazil. A total of 150 resprouts from 19 species (trees and shrubs) were experimentally coppiced. Shoot performance (number of new shoots, length, diameter and coppicing capacity) and mortality were monitored through a 15-mo period. Resprout diameter, chronic disturbance and environmental factors (rainfall, soil fertility and light availability) were assessed as explanatory variables. Of the144 coppiced resprouts, 72.2 % produced new shoots, with a total of 217 new shoots across the 19 focal species and emerged vigorously across all resprout types (root, root collar and stem). Shoot density reached 1.5 ± 1.2 shoots per resprout, with a length of 11.33 ± 10.1 cm and a diameter of 0.2 ± 0.1 cm. When pooling all new shoots across species, resprout diameter was found to have a positive effect on shoot number, length, diameter and coppicing capacity. At species level, resprout diameter was also the most important predictor. However, chronic disturbance had both negative and positive effects on some performance indicators of some species, as did rainfall, soil fertility and leaf area index. Finally, mortality rate was not affected by any of the explanatory variables assessed, neither at species nor community level. Our findings suggest that in human-modified landscapes of Caatinga dry forest, woody flora probably contain a large number of resprouting species (dominant species, in some cases), which are able to vigorously produce new shoots in response to biomass loss. Furthermore, we found shoot performance to be mediated by variables that affect plant growth. Although the Caatinga dry forest flora did not evolve in the presence of fire, resprouting is expected to play a key role in its regeneration and dynamics.