SoilsWest, UWA School of Agriculture and Environment, Faculty of Science, The University of Western Australia, Crawley, WA, 6009, Australia.
Department of Agriculture and Food Western Australia, South Perth, WA, 6151, Australia.
Sci Rep. 2017 Oct 12;7(1):13032. doi: 10.1038/s41598-017-13094-9.
One of the greatest contemporary challenges in terrestrial ecology is to determine the impact of climate change on the world's ecosystems. Here we investigated how wetting patterns (frequency and intensity) and nutrient additions altered microbial biomass and CO-C loss from a semi-arid soil. South-western Australia is predicted to experience declining annual rainfall but increased frequency of summer rainfall events when soil is fallow. Agricultural soils (0-10 cm at 10 °C or 25 °C) received the same total amount of water (15 mL over 30 days) applied at different frequency; with either nil or added nitrogen and phosphorus. Smaller more frequent wetting applications resulted in less CO-C loss (P < 0.001); with cumulative CO-C loss 35% lower than a single wetting event. This coincided with increased microbial biomass C at 25 °C but a decline at 10 °C. Increasing nutrient availability decreased CO-C loss only under a single larger wetting event. While bacterial and fungal abundance remained unchanged, archaeal abundance and laccase-like copper monooxidase gene abundance increased with more frequent wetting at 25 °C. Our findings suggest smaller more frequent summer rainfall may decrease CO emissions compared to infrequent larger events; and enhance microbial C use efficiency where sufficient background soil organic matter and nutrients are available.
陆地生态学当前面临的最大挑战之一是确定气候变化对世界生态系统的影响。在这里，我们研究了湿润模式（频率和强度）和养分添加如何改变半干旱土壤中的微生物生物量和 CO-C 损失。当土壤休耕时，澳大利亚西南部预计年降雨量减少，但夏季降雨事件的频率增加。农业土壤（10°C 或 25°C 时 0-10cm）以相同的总水量（30 天内 15 毫升）以不同的频率施加；要么没有添加氮和磷，要么添加氮和磷。较小、更频繁的湿润应用导致 CO-C 损失减少（P<0.001）；与单次湿润事件相比，累积 CO-C 损失低 35%。这与 25°C 时微生物生物量 C 的增加以及 10°C 时的下降相吻合。在单次较大的湿润事件下，增加养分供应仅降低 CO-C 损失。虽然细菌和真菌丰度保持不变，但在 25°C 时，随着湿润频率的增加，古菌丰度和漆酶样铜单氧化酶基因丰度增加。我们的研究结果表明，与不频繁的大雨事件相比，较小、更频繁的夏季降雨可能会减少 CO 排放；并在有足够的背景土壤有机质和养分的情况下提高微生物 C 的利用效率。
