Attributes that ensure Cerrado shrub layer resilience after afforestation: The case of Psidium grandifolium

Abstract

The Cerrado, the most biodiverse savanna, has been losing its natural areas through conversion to agricultural land. In the Santa Barbara Ecological Station (SBES), more than 136.4 ha of open Cerrado vegetation were converted into pine plantations in the 1960s-1970s. Nonetheless, nowadays techniques such as clear-cutting pine trees and burning of the remaining material have been used to recover the native vegetation in those areas. In one of these recovering areas, some native species have resprouted, particularly Psidium grandifolium, which naturally occurs in open Cerrado vegetation. Here, we aimed to elucidate which attributes ensured the resilience of this species after decades of afforestation. To do so, we compare the belowground systems, bud banks, chemical contents of roots and vessel characteristics of P. grandifolium occurring in a natural open Cerrado area and an area under regeneration after the clear-cutting of pine and later burning at SBES. In both study areas, plants showed xylopodium whose upper parts consisted of a thin cauline axis joined to a lignified tuberous root with fusiform morphology. In the natural area, the xylopodia were orientated vertically on the ground, while in the regenerating area, there was a curvature in the cauline axis, changing the xylopodia orientation to a horizontal position. The belowground bud bank was three times greater in the area under regeneration. Roots presented significant differences in the concentrations of total soluble carbohydrates and flavonoids between study areas. Our results also demonstrated that plants with thickened bud-bearing belowground systems held great resilience capacity, even when the structures were damaged by soil management before pine planting. Individuals of P. grandifolium managed to remain dormant in the plantations for decades until the conditions for resprouting were adequate. This work showed a series of plastic responses that Cerrado species present when submitted to afforestation and different growing conditions.