Data and code from: Limited responses of lizard assemblages to experimental fire regimes in an Australian tropical savanna

Disturbance is fundamental to ecosystem dynamics and its management is foundational to effective ecosystem management for the conservation of biodiversity. Fire is a key agent of disturbance influencing faunal communities in many terrestrial ecosystems, and it underpins the conservation management of fire-prone ecosystems. However, we have a limited understanding of how faunal communities in fire-prone ecosystems respond to variation in fire frequency. Here, we use a long-term fire experiment to investigate the effect of fire frequency on lizard assemblages in an Australian tropical savanna. We sampled lizards using pitfall traps, funnel traps and direct searches in replicate (n = 3) 1-ha plots that had been burnt every one, three or five years or left unburnt for 18 years. We found no significant variation in total lizard abundance or the collective abundances of mesic, semi-arid or widespread biogeographic groups. The abundance of only one of the five most common species was significantly related to fire frequency. Species richness decreased with increased fire frequency and showed a humped relationship with woody cover. Species composition was slightly better explained by variation in woody cover than fire frequency, with both effects relatively weak. Although woody cover declined with increasing fire frequency, it varied markedly both within and among plots experiencing the same fire treatment, which explains why fire frequency was not as strong as woody cover as a predictor of variation in lizard assemblages. Our findings show that the diverse lizard assemblage in our tropical savanna system exhibits a very limited response to variation in long-term fire frequency, and attribute this to the marked small-scale variation in woody cover that was inherent under any fire treatment. We conclude that small-scale patchiness in vegetation cover plays a critical role in the responses to fire of faunal species with relatively small foraging territories, reducing a need for larger-scale fire mosaics under a ‘pyrodiversity begets biodiversity’ paradigm.

干扰是生态系统动态的核心要素，而干扰管理亦是开展以保护生物多样性为目标的有效生态系统管理的核心基础。火灾是众多陆地生态系统中影响动物群落的关键干扰因子，也是易火生态系统保护管理的核心支撑手段。然而，目前我们对易火生态系统中的动物群落如何响应火频变化的认知仍十分有限。本研究依托长期火烧控制实验，探究火频变化对澳大利亚热带稀树草原蜥蜴群落的影响。我们采用地面陷阱、漏斗陷阱及样地直接搜寻法，对4组重复设置的1公顷样地（每组含3个重复样地）内的蜥蜴进行采样；这4组样地分别接受每1年火烧一次、每3年火烧一次、每5年火烧一次的处理，或保持18年未过火。研究结果显示，蜥蜴总个体数，以及湿生、半干旱及广布生物地理类群的总个体数均未出现显著变化。仅5个最常见物种中的1个，其个体数与火频变化存在显著相关性。物种丰富度随火频升高而降低，且与木本覆盖度呈单峰（驼峰）型相关关系。相较于火频变化，木本覆盖度的变异对蜥蜴群落组成的解释度略高，但二者的影响均相对较弱。尽管木本覆盖度随火频升高而降低，但在同一火烧处理的样地内部及样地之间，木本覆盖度均存在显著变异，这也解释了为何火频作为蜥蜴群落变异的预测因子，其解释力弱于木本覆盖度。本研究结果表明，该热带稀树草原系统中的多样蜥蜴群落，对长期火频变化的响应极为有限；我们将这一现象归因于：无论采用何种火烧处理，木本覆盖度均存在显著的小尺度固有变异。本研究总结认为，对于觅食领地相对较小的动物类群而言，植被覆盖的小尺度斑块性在其响应火烧干扰的过程中发挥着关键作用；这一结果也表明，在‘火多样性催生生物多样性’的范式下，并不需要构建更大尺度的火烧镶嵌格局。