Fire acts as an ecological filter determining species diversity and composition of communities. In tropical savannas in Central Brazil, natural fire happens through lightning, but anthropogenic fire is also common, either controlled fire prescribed for management of vegetation and to promote grass growth or accidental and intentional fires related to deforestation and land use changes. Frequent fire events can have a negative effect on biodiversity by causing deaths of susceptible organisms, as well as through the homogenization of vegetation. Besides the composition of plant and animal species, fire also modifies biotic interactions, such as pollination, which impact ecosystem functioning. Here, we evaluated how time since the last fire event (hereafter postfire time interval) affects the structure, beta diversity of interactions and specialization of plants and floral visitors in a naturally burned Cerrado area. Postfire time interval had no effect on the structure of interaction networks and community diversity metrics, including beta-diversity of interactions. We did, however, find a positive relationship between flower abundance and postfire time intervals, and a negative effect of postfire time intervals on floral visitor species-level specialization. Thus, the negative effect of postfire time intervals on floral visitor specialization may be explained by the lower resource availability in areas recently burnt. The lack of strong and consistent effect of time interval since the last fire on plant-pollinator interactions from the Cerrado probably results from the resilience of these interactions to natural fires, which is a common element in this ecosystem. Increased frequency of more intense anthropogenic fires, however, may have stronger effects on biodiversity, and deserves further investigation in this biodiversity hotspot.

火是决定物种多样性和群落组成的生态过滤器。在巴西中部的热带稀树草原，自然火灾是通过闪电发生的，但人为火灾也很常见，要么是为管理植被和促进草生长而规定的受控火灾，要么是与森林砍伐和土地利用变化相关的意外和故意火灾。频繁的火灾事件会导致易感生物死亡以及植被同质化，从而对生物多样性产生负面影响。除了植物和动物物种的组成外，火还会改变生物相互作用，例如影响生态系统功能的授粉。在这里，我们评估了自上次火灾事件以来的时间（以下称为火灾后时间间隔）如何影响结构，在自然燃烧的塞拉多地区，植物和花卉游客的互动和专业化的 Beta 多样性。Postfire 时间间隔对交互网络的结构和社区多样性指标没有影响，包括交互的 beta 多样性。然而，我们确实发现了花卉丰度和火灾后时间间隔之间的正相关关系，以及火灾后时间间隔对花卉访客物种级专业化的负面影响。因此，火灾后时间间隔对花卉游客专业化的负面影响可能是由于最近被烧毁的地区资源可用性较低。自上次火灾以来，塞拉多植物-传粉媒介相互作用的时间间隔缺乏强烈和一致的影响，这可能是由于这些相互作用对自然火灾的恢复能力，这是这个生态系统中的一个共同元素。然而，更强烈的人为火灾频率的增加可能对生物多样性产生更大的影响，值得在这个生物多样性热点地区进一步调查。