Carbohydrate dynamics in a resprouting species after severe aboveground perturbations

Abstract

Resprouting woody species adapted to perturbations store large amounts of carbon reserves to sustain plant metabolism during and resprout following perturbations. However, it is not known how carbon sources and sinks re-adjust in response to perturbations. Here, we studied when and where different reserve pools were mobilized after an aboveground perturbation, and how were new assimilates used after resprouting. Leaf gas exchange, plant organ carbon isotopic composition (δ13C) and nonstructural carbohydrate concentrations [NSC] were measured over one year in Pinus canariensis saplings subjected to complete defoliation (D) or complete defoliation plus stem damage (DD). Growth stopped completely in D and DD trees by the second month after the treatment application and during subsequent crown development. Growth resumed in most trees (60%) by the end of the growing season. Relative to control (C) trees, stem xylem [starch] decreased in D and DD during resprouting of new buds. Stem and root [starch] were also lower during growth resumption in these trees. One year after aboveground damages, leaf and root δ13C were significantly lower in D and DD, whereas [starch] recovered to values of C trees, except in roots of DD trees. Mobilization of carbon reserves from woody organs allows for resprouting and contributes to crown regeneration, stem growth resumption and wound healing in DD trees. New 13C-depleted photoassimilates contribute to these processes, and to refilling carbohydrates reserves. High [starch], plasticity in growth during and recovery of [starch] after severe aboveground disturbance, highlights high resilience of P. canariensis to perturbation.