Post-fire changes in plant growth form composition and diversity in Andean paramo grassland

Questions Fire suppression policies have been widely adopted in the paramo grasslands of the northern Andes to protect their biodiversity and ecosystem services. Paramos have been regularly burned for many years, and it is not clear how paramo vegetation will respond to significant changes in their fire regimes. This study investigates differences in plant growth form composition, light levels and soil temperatures in paramo plots representing a range of recovery times since the last fire. Location Reserva Ecologica El angel and La Bretana Nature Reserve, Carchi, Northern Ecuador. Methods We assessed the frequency of ten paramo growth forms, vegetation height, soil temperature, and light intensity in fifteen fire sites with historical records of fire (<1-15 years since fire), and one recently unburned site (at least 40 years since fire). A chronosequence of sites was used to assess potential changes in plant community composition in post-fire succession of paramo. Results The recovery of paramo vegetation after fire comprised three phases: initial recruitment with high growth form diversity, followed by reduced diversity, light and soil temperatures in dense tussock vegetation, and ultimately canopy height stratification with a return of diversity. All but one of the plant growth forms were represented in each of the three phases, and the changes reflected differences in relative abundance. Conclusions Post-fire paramo succession is characterised by clear shifts in the relative abundance of plant growth forms, ending with (co-)dominance of upright shrubs. The long-term consequences of such shifts for biodiversity and ecosystem function, given the widespread adoption of fire suppression policies in the paramo, need careful, evidence-based consideration.