Laboratory of Vegetation Ecology, Department of Biodiversity, Bioscience Institute, São Paulo State University (Unesp), Av. 24 A 1515, 13506-900 Rio Claro, SP, Brazil; Oklahoma Biological Survey & Department of Microbiology and Plant Biology, the University of Oklahoma, 111 E. Chesapeake Street, Norman, OK 73019-0390, USA.
Oklahoma Biological Survey & Department of Microbiology and Plant Biology, the University of Oklahoma, 111 E. Chesapeake Street, Norman, OK 73019-0390, USA.
Sci Total Environ. 2022 Mar 15;812:152317. doi: 10.1016/j.scitotenv.2021.152317. Epub 2021 Dec 13.
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 (CO) exchange (NEE), ecosystem transpiration (ET), soil respiration (soil CO 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.
火是热带稀树草原生态系统中的一种进化环境过滤器，改变了生物圈中的功能多样性和相关碳库以及大气和生物圈之间的通量。因此，火灾发生情况的改变（例如火灾排除）将强烈影响生态系统过程和相关动态。在这些生态系统中，火灾引起的碳输出和输入之间的抵消会低估碳动态和功能。为了确定火如何塑造开阔稀树草原生态系统的碳库和通量，我们测量了以下指标：（I）植物多样性，包括分类学（即丰富度、均匀度）和植物功能多样性（即功能多样性、功能丰富度、功能分散和群落加权平均值）；（II）结构（即地上和地下生物量、凋落物积累）；以及（III）与碳平衡相关的功能（即净生态系统二氧化碳（CO）交换（NEE）、生态系统蒸腾（ET）、土壤呼吸（土壤 CO 排放）、生态系统水分利用效率（eWUE）和总土壤有机碳（SOC）。我们发现，火促进了地上活生物量和地下生物量的生长，包括地下器官、粗根和细根生物量，并促进了更多的生物量地下分配。火还增加了功能多样性和分散度。与火灾排除的地区相比，燃烧地区的 NEE 和总 SOC 更高，而土壤呼吸记录的数值较低。ET 和 eWUE 不受火的影响。在分段 SEM 模型中，火强烈有利于功能多样性、细根和地下器官生物量，但功能多样性和生态系统结构在调节火对生态系统功能的影响方面的作用仍不清楚。火灾发生情况将影响碳平衡，火灾排除可能导致开阔稀树草原生态系统中的碳输入减少。
