Fire promotes functional plant diversity and modifies soil carbon dynamics in tropical savanna

• Published in: The Science of the total environment Vol. 812; p. 152317
• Main Authors: Teixeira, Juliana, Souza, Lara, Le Stradic, Soizig, Fidelis, Alessandra
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.03.2022; Elsevier
• Subjects: Above and belowground interactions; belowground biomass; Biomass; biosphere; carbon dioxide; Carbon dynamics; dry matter partitioning; Ecosystem; ecosystems; environmental factors; Environmental Sciences; fine roots; fire regime; Fire-prone ecosystems; Fires; Functional diversity; Grassland; Neotropical savanna; Plants; Resilience; savannas; Soil; soil organic carbon; soil respiration; species diversity; transpiration; water use efficiency; Carbon dynamics; Fire-prone ecosystems; Neotropical savanna; Above and belowground interactions; Functional diversity; Resilience
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.152317

Fire is an evolutionary environmental filter in tropical savanna ecosystems altering functional diversity and associated C pools in the biosphere and fluxes between the atmosphere and biosphere. Therefore, alterations in fire regimes (e.g. fire exclusion) will strongly influence ecosystem processes and associated dynamics. In those ecosystems C dynamics and functions are underestimated by the fire-induced offset between C output and input. To determine how fire shapes ecosystem C pools and fluxes in an open savanna across recently burned and fire excluded areas, we measured the following metrics: (I) plant diversity including taxonomic (i.e. richness, evenness) and plant functional diversity (i.e. functional diversity, functional richness, functional dispersion and community weighted means); (II) structure (i.e. above- and below-ground biomass, litter accumulation); and (III) functions related to C balance (i.e. net ecosystem carbon dioxide (CO2) exchange (NEE), ecosystem transpiration (ET), soil respiration (soil CO2 efflux), ecosystem water use efficiency (eWUE) and total soil organic C (SOC). We found that fire promoted aboveground live and belowground biomass, including belowground organs, coarse and fine root biomass and contributed to higher biomass allocation belowground. Fire also increased both functional diversity and dispersion. NEE and total SOC were higher in burned plots compared to fire-excluded plots whereas soil respiration recorded lower values in burned areas. Both ET and eWUE were not affected by fire. Fire strongly favored functional diversity, fine root and belowground organ biomass in piecewise SEM models but the role of both functional diversity and ecosystem structure to mediate the effect of fire on ecosystem functions remain unclear. Fire regime will impact C balance, and fire exclusion may lead to lower C input in open savanna ecosystems. [Display omitted] •Alterations of fire regimes influence tropical savannas water and carbon exchange.•Fire presence modified carbon balance increasing soil and belowground carbon input.•Fire promotes functional diversity due to plant regeneration post-fire strategies.•Fire exclusion leads to losses on soil carbon and functional diversity.