Post-fire environments are favourable for plant functioning of seeder and resprouter Mediterranean shrubs, even under drought

Abstract

Understanding how drought affects seeder and resprouter plants during post-fire regeneration is important for the anticipation of Mediterranean vegetation vulnerability in a context of increasing drought and fire caused by climate change. A Mediterranean shrubland was subjected to various drought treatments (including 45% rainfall reduction, 7 months drought yr−1), before and after experimental burning, by means of a rainout–shelter system with an irrigation facility. Predawn shoot water potential (Ψpd), relative growth rate (RGR), specific leaf area (SLA) and bulk leaf carbon isotopic composition (δ13C) were monitored in the main woody species during the first 3 yr after fire. Cistus ladanifer seedlings showed higher Ψpd, RGR and SLA, and lower δ13C, than unburned plants during the first two post-fire years. Seedlings under drought maintained relatively high Ψpd, but suffered a decrease in Ψpd and RGR, and an increase in δ13C, relative to control treatments. Erica arborea, E. scoparia and Phillyrea angustifolia resprouts had higher Ψpd and RGR than unburned plants during the first post-fire year. Resprouters were largely unaffected by drought. Overall, despite marked differences between the two functional groups, post-fire environments were favourable for plant functioning of both seeder and resprouter shrubs, even under the most severe drought conditions implemented.