Physical disturbances, such as fire, may affect the relationship between ants and plants. We evaluated the extent to which severe fires alter the protective effect of ants against the herbivores of an extrafloral-nectary bearing tree. We performed an ant removal experiment and sampled the ant fauna from the same trees over 4 years: the pre-fire year, the fire-year, and again 1 and 2 years later. Ants reduced insect herbivory in the pre-fire year and in the fire-year but failed to provide any plant protection in the two years after fire. The magnitude of the ant effect on herbivory did not differ between the pre-fire year and the fire-year. Fire reduced the abundance of ants with strictly arboreal-nesting habits. However, in the fire year (but not in the subsequent ones), this decline was compensated by an increase in the abundance of arboreal generalists and ground-nesting ants foraging in trees. Our results indicate that severe fires can affect the strength and direction of the ant effects on herbivory by altering the structure of the arboreal ant community and the abundance of insect herbivores. Fire disturbance is thus an important factor of conditionality of ant-plant mutualisms in fire-prone habitats, like the Cerrado savannas.

中文翻译：

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强烈的大火改变了蚂蚁和新热带大草原树之间互惠互利的结果

诸如火的物理干扰可能会影响蚂蚁与植物之间的关系。我们评估了大火在多大程度上改变了蚂蚁对花外蜜腺结实树的草食动物的保护作用。我们进行了一次蚂蚁清除实验，并在4年的时间里从同一棵树上采样了蚂蚁动物区系：火灾前的一年，火灾的年份以及1年和2年之后。蚂蚁在大火前和大火年减少了昆虫的食草性，但在大火后的两年中未能提供任何植物保护。在放火前和放火年之间，蚂蚁对草食动物的影响程度没有差异。火减少了严格树栖嵌套习惯的蚂蚁的数量。但是，在火灾年度（但在随后的一年中除外），这种下降被树木上的全能专家和在树上觅食的地面嵌套蚂蚁数量的增加所弥补。我们的结果表明，大火可以通过改变树栖蚂蚁群落的结构和昆虫食草动物的数量来影响蚂蚁对食草动物的作用强度和方向。因此，火势干扰是易火生境（如Cerrado savannas）中蚂蚁与植物互生条件的重要因素。