Fire and grazing are large-scale disturbances that shape the structure and function of open habitats. In temperate grasslands of southern South America, fire is used as a management tool to control tussock grasses and improve forage quality. In this study, we examined if fire and two of its components (heat and smoke) affect germination from the soil seed bank of a temperate grassland in Uruguay. Soil samples were extracted from a recently burned site and from an adjacent area that had not been burned for at least 4 years. The latter was subjected to four treatments: (1) heat shock, (2) smoke, (3) heat shock and smoke and (4) control. The samples were placed in a germination chamber and germination was recorded for 140 days. Field burn was the treatment that differed most from the control. This treatment produced a significant increase in density and richness of germinants and the germination peak preceded those of the remaining treatments. The three treatments involving fire-related cues did not affect the seedling richness and density, but the germination of some individual species was enhanced by some of them, mainly those in which the seeds were smoked. Our results show that fire and its components stimulate the germination of some species of the Río de la Plata grasslands, contrary to what had been observed previously in the region. We also suggest that, unlike Mediterranean-type systems, other fire cues, alone or in combination with heat and smoke, may promote germination after a fire event.

中文翻译：

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田间烧伤与火灾相关线索：南美温带草原土壤种子库的发芽

火灾和放牧是影响开放栖息地结构和功能的大规模扰动。在南美洲南部的温带草原，火被用作控制草丛和提高牧草质量的管理工具。在这项研究中，我们检查了火及其两种成分（热量和烟雾）是否会影响乌拉圭温带草原土壤种子库的发芽。土壤样本是从最近被烧毁的地点和至少 4 年没有被烧毁的邻近地区提取的。后者经过四种处理：（1）热休克，（2）烟雾，（3）热休克和烟雾以及（4）控制。将样品放入发芽室并记录发芽 140 天。现场烧伤是与对照最不同的治疗方法。这种处理使发芽剂的密度和丰富度显着增加，并且发芽高峰早于其余处理的发芽高峰。涉及火相关线索的三个处理不影响幼苗的丰富度和密度，但其中一些促进了某些个体物种的发芽，主要是那些种子被熏制的。我们的研究结果表明，与之前在该地区观察到的情况相反，火及其成分会刺激 Río de la Plata 草原某些物种的发芽。我们还建议，与地中海型系统不同，其他火灾线索，单独或与热量和烟雾相结合，可能会在火灾事件后促进发芽。涉及火相关线索的三个处理不影响幼苗的丰富度和密度，但其中一些促进了某些个体物种的发芽，主要是那些种子被熏制的。我们的研究结果表明，与之前在该地区观察到的情况相反，火及其成分会刺激 Río de la Plata 草原某些物种的发芽。我们还建议，与地中海型系统不同，其他火灾线索，单独或与热量和烟雾相结合，可能会在火灾事件后促进发芽。涉及火相关线索的三个处理不影响幼苗的丰富度和密度，但其中一些促进了某些个体物种的发芽，主要是那些种子被熏制的。我们的研究结果表明，与之前在该地区观察到的情况相反，火及其成分会刺激 Río de la Plata 草原某些物种的发芽。我们还建议，与地中海型系统不同，其他火灾线索，单独或与热量和烟雾相结合，可能会在火灾事件后促进发芽。我们的研究结果表明，与之前在该地区观察到的情况相反，火及其成分会刺激 Río de la Plata 草原某些物种的发芽。我们还建议，与地中海型系统不同，其他火灾线索，单独或与热量和烟雾相结合，可能会在火灾事件后促进发芽。我们的研究结果表明，与之前在该地区观察到的情况相反，火及其成分会刺激 Río de la Plata 草原某些物种的发芽。我们还建议，与地中海型系统不同，其他火灾线索，单独或与热量和烟雾相结合，可能会在火灾事件后促进发芽。