Physiological and Regenerative Plant Traits Explain Vegetation Regeneration under Different Severity Levels in Mediterranean Fire-Prone Ecosystems

Sara Huerta,Susana Suárez-Seoane,Víctor Fernández-García,Leonor Calvo,Elena Marcos

doi:10.3390/f12020149

Abstract

In Mediterranean fire-prone ecosystems, plant functional traits and burn severity have decisive roles in post-fire vegetation recovery. These traits may reflect plant fitness to fire regimes in the Mediterranean Basin. The aim of this study was to evaluate the effect of burn severity on post-fire vegetation regeneration through plant functional (physiological and regenerative) traits in two Mediterranean ecosystems: one more humid and colder (Cabrera in León province, NW Spain), and another characterized by a longer summer drought (Gátova in Valencia province, SE Spain). A total of 384 and 80 field plots (2 m × 2 m) were fixed in Cabrera and Gátova, respectively. In each burned plot, we quantified burn severity by means of the composite burn index (CBI), differentiating three severity levels (low, moderate, and high), and evaluated post-fire vegetation regeneration one and two years after wildfires. We measured the percentage cover of each species and classified them according to physiological (specific leaf area and N2-fixing capacity) and regenerative traits (reproductive strategy, bud bank location, and heat-stimulated germination). The main results showed that in Cabrera, burn severity had significant effects on vegetation cover independently of plant functional traits. In Gátova, burn severity effects differed among functional traits. In this site, the cover of plants with low specific leaf area and without heat-stimulation and N2-fixing capacity was negatively related to burn severity. On the contrary, the cover of N2-fixers and species with resprouting ability and heat-stimulated germination rose with increasing burn severity. In general, vegetation cover showed a more pronounced increased over time in the more humid area, mainly under the effect of high severity. The results of this research highlighted the importance of the use of plant functional traits as a driver to understand the response of different ecosystems to current fire regimes, which could be relevant for pre- and post-fire management.

Highlights

IntroductionClimate change and increasing fuel accumulation caused by land use abandonment (mainly driven by a reduction in traditional agriculture, livestock grazing, and rural population density) have contributed to the alteration of the fire regime in the Mediterranean Basin [3]
Climate change and increasing fuel accumulation caused by land use abandonment have contributed to the alteration of the fire regime in the Mediterranean Basin [3]
These changes in the fire regime have influenced plant community structure [8], especially the presence of species with reproductive traits that allow them to persist after fire [9,10]

Summary

Introduction

Climate change and increasing fuel accumulation caused by land use abandonment (mainly driven by a reduction in traditional agriculture, livestock grazing, and rural population density) have contributed to the alteration of the fire regime in the Mediterranean Basin [3]. This has led to an increase in the number of fires [4], burned area [2], and burn severity [5,6,7]. Climatic conditions characterized by a decrease in the water availability for plants constrains their response to wildfire, mainly because of its implication in the productivity of the plant community after fire [15]

Objectives

Methods

Conclusion