Drivers of post-fire resprouting-based resilience of co-occurring species in Mediterranean SE Spain.

Abstract

Resprouting is a major mechanism of post-fire persistence in Mediterranean woody plants, but quantifying its contribution to resilience is difficult when pre-disturbance data are unavailable. We assessed post-fire resprouting-based resilience in nine co-occurring woody species from southeastern Iberia and tested whether its drivers were consistent across species. We developed species-specific allometric equations from unburned individuals to estimate pre-fire biovolume. Resilience was quantified as the normalized biovolume recovery rate (NBRR), based on the ratio between post-fire biovolume measured 10-12 years after fire and estimated pre-fire biovolume. We then modelled NBRR as a function of microenvironmental conditions, fire severity, climatic niche position and plant size. Allometric models successfully estimated pre-fire biovolume and enabled resilience quantification. All species resprouted, and six exceeded their estimated pre-fire biovolume. However, resilience drivers varied among species. Environmental harshness reduced resilience in three species, fire severity increased resilience in four species under predominantly low-to-moderate severity, and larger pre-fire individuals generally showed lower recovery, whereas climatic niche position did not explain resilience. Plant-level biovolume modelling provides a practical framework to quantify post-fire resilience in resprouting species when pre-fire data are lacking. Strong interspecific variation in resilience drivers suggests that complementary responses among co-occurring species may enhance resilience at the community level.