Rodríguez Pérez Héctor, Borrel Guillaume, Leroy Céline, Carrias Jean-François, Corbara Bruno, Srivastava Diane S, Céréghino Régis
CNRS, Ecologie des Forêts de Guyane (AgroParisTech, CIRAD, INRA, Université de Guyane, Université des Antilles), Campus Agronomique, 97379, Kourou Cedex, France.
Univ Rennes, CNRS, ECOBIO UMR 6553, 35000, Rennes, France.
Oecologia. 2018 May;187(1):267-279. doi: 10.1007/s00442-018-4123-5. Epub 2018 Mar 24.
Future climate scenarios forecast a 10-50% decline in rainfall in Eastern Amazonia. Altered precipitation patterns may change important ecosystem functions like decomposition through either changes in physical and chemical processes or shifts in the activity and/or composition of species. We experimentally manipulated hydroperiods (length of wet:dry cycles) in a tank bromeliad ecosystem to examine impacts on leaf litter decomposition. Gross loss of litter mass over 112 days was greatest in continuously submersed litter, lowest in continuously dry litter, and intermediate over a range of hydroperiods ranging from eight cycles of 7 wet:7 dry days to one cycle of 56 wet:56 dry days. The resilience of litter mass loss to hydroperiod length is due to a shift from biologically assisted decomposition (mostly microbial) at short wet:dry hydroperiods to physicochemical release of dissolved organic matter at longer wet:dry hydroperiods. Biologically assisted decomposition was maximized at wet:dry hydroperiods falling within the range of ambient conditions (12-22 consecutive dry days) but then declined under prolonged wet:dry hydroperiods (28 and 56 dry days. Fungal:bacterial ratios showed a similar pattern as biologically assisted decomposition to hydroperiod length. Our results suggest that microbial communities confer functional resilience to altered hydroperiod in tank bromeliad ecosystems. We predict a substantial decrease in biological activity relevant to decomposition under climate scenarios that increase consecutive dry days by 1.6- to 3.2-fold in our study area, whereas decreased frequency of dry periods will tend to increase the physicochemical component of decomposition.
未来气候情景预测，亚马孙东部地区的降雨量将下降10%-50%。降水模式的改变可能会通过物理和化学过程的变化，或物种活动和/或组成的改变，而改变诸如分解等重要的生态系统功能。我们通过实验操纵了凤梨科植物水箱生态系统中的水文周期（湿：干周期的长度），以研究其对凋落物分解的影响。在112天内，凋落物质量的总损失在持续淹没的凋落物中最大，在持续干燥的凋落物中最小，在一系列水文周期（从7湿：7干天的8个周期到56湿：56干天的1个周期）中处于中间水平。凋落物质量损失对水文周期长度的恢复力，是由于在短湿：干水文周期中从生物辅助分解（主要是微生物分解）向长湿：干水文周期中溶解有机物的物理化学释放的转变。生物辅助分解在湿：干水文周期处于环境条件范围内（连续12-22个干燥天）时达到最大值，但在延长的湿：干水文周期（28和56个干燥天）下则下降。真菌：细菌比率与生物辅助分解对水文周期长度的模式相似。我们的结果表明，微生物群落赋予凤梨科植物水箱生态系统中改变的水文周期功能恢复力。我们预测，在我们的研究区域，在气候情景下，连续干燥天数增加1.6至3.2倍，与分解相关的生物活性将大幅下降，而干旱期频率的降低将倾向于增加分解的物理化学成分。
