Could Fire Severity Promotes the Biosynthesis of Bioactive Compounds as a Strategy to Improve Plant Survival?

Abstract

Fire has effects on diverse aspects of plant functioning and development, many of themlinked to survival. However, the response of native vegetation to this disturbance possibly revealsa plant strategy to tolerate fire linked to the biosynthesis of compounds such as chlorophylls andsecondary metabolites. The aim of this study was to evaluate whether fire severity could promotebiochemical tolerance to fire by influencing the biosynthesis of chemical compounds. To test this,six woody species from the Chaco region were exposed to an experimental burn of medium severityat the end of fire season in the study area. In this burn, individual plots for each plant were established. Fire severity was estimated visually as the burnt biomass of each plant, which was considered as the percentage of the loss of aboveground biomass. Then, the biochemical plant response tofire was studied, through the changes in the concentration of photosynthetic pigments (chlorophylland carotenoids), and secondary metabolites (phenolic compounds and tannins). The metabolitequantification was carried out by using spectrophotometric methods. As a result, a strong correlation was found between the biosynthesis of metabolites in response to fire and the amount of burntbiomass during the experimental burns. This correlation could be considered as an indicator of theburnt plant response to stress. In our results, shrubby species showed both the higher amount ofburnt biomass and the enhanced biosynthesis of compounds in the resprouts post-fire, which couldbe related to the capacity of these species to be established in disturbed environments. Our studyprovides new insights into the understanding of the plant strategies to fire tolerance and resiliencein natural environments