Department of Plant and Wildlife Sciences, Brigham Young University, Provo, UT, 84602, USA.
Department of Earth Science, Utah Valley University, 800 W. University Parkway, Orem, UT, 84058, USA.
Oecologia. 2024 Oct;206(1-2):141-149. doi: 10.1007/s00442-024-05617-9. Epub 2024 Sep 19.
Consumers exert top-down controls on dryland ecosystem function, but recent increases in fire activity may alter consumer communities in post-fire environments. Native consumers, including ants and rodents, likely have critical roles in defining post-fire plant community assembly and resilience to biological invasions. This study aimed to understand how western harvester ants (Pogonomyrmex occidentalis) that form mounds and large vegetation-free disks that significantly influence plant community structure in the Great Basin Desert respond to fire and rodent community abundance. We tested this by installing treatment plots that excluded or allowed rodents and were burned or unburned in a full factorial design. We measured ant disk and mound size and density in each experimental plot. Fire increased ant mound density by 126% compared to unburned plots. Rodent presence decreased mound density by 59%, mound diameter by 13%, and mound height by 166%. We also show an interaction where the adverse effects of rodents on ant disk density were greater in burned than in unburned plots. The results suggest that booms in rodent populations are likely to have suppressive effects on ant mound and disk formation in native shrublands but that harvester ants may be released from rodent competition with the emergence of invasive grass-fire cycles.
消费者对旱地生态系统功能施加自上而下的控制，但最近火灾活动的增加可能会改变火灾后的消费者群体。本地消费者，包括蚂蚁和啮齿动物，可能在定义火灾后植物群落组成和对生物入侵的恢复力方面发挥关键作用。本研究旨在了解在大盆地沙漠中形成土丘和大无植被盘的西部收获蚁（Pogonomyrmex occidentalis）如何应对火灾和啮齿动物群落丰度。我们通过安装排除或允许啮齿动物存在的处理地块，并以完全析因设计进行燃烧或不燃烧来测试这一点。我们测量了每个实验地块中的蚂蚁盘和土丘的大小和密度。与未燃烧的地块相比，火灾使蚁丘密度增加了 126%。啮齿动物的存在使蚁丘密度降低了 59%，蚁丘直径降低了 13%，蚁丘高度降低了 166%。我们还表明存在一种相互作用，即在燃烧和未燃烧的地块中，啮齿动物对蚂蚁盘密度的不利影响在燃烧的地块中更大。结果表明，啮齿动物种群的激增可能对本地灌木林的蚂蚁土丘和盘形成具有抑制作用，但随着入侵草火循环的出现，收获蚁可能会摆脱与啮齿动物的竞争。
