Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA.
Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA.
ISME J. 2023 Dec;17(12):2290-2302. doi: 10.1038/s41396-023-01536-4. Epub 2023 Oct 23.
Ice-free terrestrial environments of the western Antarctic Peninsula are expanding and subject to colonization by new microorganisms and plants, which control biogeochemical cycling. Measuring growth rates of microbial populations and ecosystem carbon flux is critical for understanding how terrestrial ecosystems in Antarctica will respond to future warming. We implemented a field warming experiment in early (bare soil; +2 °C) and late (peat moss-dominated; +1.2 °C) successional glacier forefield sites on the western Antarctica Peninsula. We used quantitative stable isotope probing with HO using intact cores in situ to determine growth rate responses of bacterial taxa to short-term (1 month) warming. Warming increased the growth rates of bacterial communities at both sites, even doubling the number of taxa exhibiting significant growth at the early site. Growth responses varied among taxa. Despite that warming induced a similar response for bacterial relative growth rates overall, the warming effect on ecosystem carbon fluxes was stronger at the early successional site-likely driven by increased activity of autotrophs which switched the ecosystem from a carbon source to a carbon sink. At the late-successional site, warming caused a significant increase in growth rate of many Alphaproteobacteria, but a weaker and opposite gross ecosystem productivity response that decreased the carbon sink-indicating that the carbon flux rates were driven more strongly by the plant communities. Such changes to bacterial growth and ecosystem carbon cycling suggest that the terrestrial Antarctic Peninsula can respond fast to increases in temperature, which can have repercussions for long-term elemental cycling and carbon storage.
南极半岛西部无冰陆地环境正在扩张，并受到新的微生物和植物的殖民，这些生物控制着生物地球化学循环。测量微生物种群和生态系统碳通量的增长率对于了解南极洲的陆地生态系统将如何应对未来的变暖至关重要。我们在南极半岛西部的早期（裸土；+2°C）和晚期（泥炭藓为主；+1.2°C）演替冰川前缘地点实施了野外增温实验。我们使用原位完整核心的定量稳定同位素探测 HO 来确定细菌分类群对短期（1 个月）增温的生长率响应。增温增加了两个地点的细菌群落的生长率，甚至使在早期地点表现出显著生长的分类群数量增加了一倍。增长反应因分类群而异。尽管增温总体上诱导了细菌相对生长率的相似响应，但在早期演替地点，生态系统碳通量的增温效应更强——这可能是由于自养生物活性的增加，使生态系统从碳源转变为碳汇。在晚期演替地点，增温导致许多α变形菌的生长率显著增加，但净生态系统生产力的响应较弱且相反，减少了碳汇——表明碳通量速率受植物群落的驱动更强。这种细菌生长和生态系统碳循环的变化表明，南极半岛的陆地可以快速响应温度的升高，这可能对长期元素循环和碳储存产生影响。
