Brassard François, Murphy Brett P, Andersen Alan N
Charles Darwin University, Darwin, Northwest Territory, Australia.
Ecol Appl. 2024 Oct;34(7):e3025. doi: 10.1002/eap.3025. Epub 2024 Aug 21.
Fire is a powerful tool for conservation management at a landscape scale, but a rigorous evidence base is often lacking for understanding its impacts on biodiversity in different biomes. Fire-induced changes to habitat openness have been identified as an underlying driver of responses of faunal communities, including for ants. However, most studies of the impacts of fire on ant communities consider only epigeic (foraging on the soil surface) species, which may not reflect the responses of species inhabiting other vertical strata. Here, we examine how the responses of ant communities vary among vertical strata in a highly fire-prone biome. We use a long-term field experiment to quantify the effects of fire on the abundance, richness, and composition of ant assemblages of four vertical strata (subterranean, leaf litter, epigeic, and arboreal) in an Australian tropical savanna. We first document the extent to which each stratum harbors distinct assemblages. We then assess how the assemblage of each stratum responds to three fire-related predictors: fire frequency, fire activity, and vegetation cover. Each stratum harbored a distinct ant assemblage and showed different responses to fire. Leaf litter and epigeic ants were most sensitive to fire because it directly affects their microhabitats, but they showed contrasting negative and positive responses, respectively. Subterranean ants were the least sensitive because of the insulating effects of soil. Our results show that co-occurring species of the same taxonomic group differ in the strength and direction of their response to fire depending on the stratum they inhabit. As such, effective fire management for biodiversity conservation should consider species in all vertical strata.
火灾是景观尺度上保护管理的有力工具，但在理解其对不同生物群落中生物多样性的影响方面，往往缺乏严格的证据基础。火灾引起的栖息地开放性变化已被确定为动物群落（包括蚂蚁）反应的一个潜在驱动因素。然而，大多数关于火灾对蚂蚁群落影响的研究只考虑地表活动（在土壤表面觅食）的物种，这可能无法反映栖息在其他垂直层次的物种的反应。在这里，我们研究了在一个火灾频发的生物群落中，蚂蚁群落在不同垂直层次间的反应是如何变化的。我们利用一项长期野外实验，来量化火灾对澳大利亚热带稀树草原四个垂直层次（地下、落叶层、地表活动和树栖）蚂蚁群落的丰富度、物种丰富度和组成的影响。我们首先记录每个层次容纳不同群落的程度。然后，我们评估每个层次的群落如何对与火灾相关的三个预测因素做出反应：火灾频率、火灾活动和植被覆盖。每个层次都有独特的蚂蚁群落，并且对火灾表现出不同的反应。落叶层和地表活动的蚂蚁对火灾最为敏感，因为火灾直接影响它们的微生境，但它们分别表现出相反的负面和正面反应。由于土壤的隔热作用，地下蚂蚁最不敏感。我们的结果表明，同一分类群中同时出现的物种，根据它们所栖息的层次，对火灾的反应强度和方向有所不同。因此，为保护生物多样性而进行的有效火灾管理应考虑所有垂直层次的物种。
