Zhao Fazhu, He Liyuan, Bond-Lamberty Ben, Janssens Ivan A, Wang Jieying, Pang Guowei, Wu Yuwei, Xu Xiaofeng
Shaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity, Northwest University, Xi'an 710127, China.
Biology Department, San Diego State University, San Diego, CA 92182, USA.
PNAS Nexus. 2022 Nov 4;1(5):pgac254. doi: 10.1093/pnasnexus/pgac254. eCollection 2022 Nov.
Soil microbes ultimately drive the mineralization of soil organic carbon and thus ecosystem functions. We compiled a dataset of the seasonality of microbial biomass carbon (MBC) and developed a semi-mechanistic model to map monthly MBC across the globe. MBC exhibits an equatorially symmetric seasonality between the Northern and Southern Hemispheres. In the Northern Hemisphere, MBC peaks in autumn and is minimal in spring at low latitudes (<25°N), peaks in the spring and is minimal in autumn at mid-latitudes (25°N to 50°N), while peaks in autumn and is minimal in spring at high latitudes (>50°N). This latitudinal shift of MBC seasonality is attributed to an interaction of soil temperature, soil moisture, and substrate availability. The MBC seasonality is inconsistent with patterns of heterotrophic respiration, indicating that MBC as a proxy for microbial activity is inappropriate at this resolution. This study highlights the need to explicitly represent microbial physiology in microbial models. The interactive controls of environments and substrate on microbial seasonality provide insights for better representing microbial mechanisms in simulating ecosystem functions at the seasonal scale.
土壤微生物最终驱动土壤有机碳的矿化，进而影响生态系统功能。我们汇编了微生物生物量碳（MBC）季节性的数据集，并开发了一个半机制模型来绘制全球每月的MBC。MBC在南北半球之间呈现出赤道对称的季节性。在北半球，低纬度地区（<25°N）的MBC在秋季达到峰值，在春季达到最小值；中纬度地区（25°N至50°N）的MBC在春季达到峰值，在秋季达到最小值；而高纬度地区（>50°N）的MBC在秋季达到峰值，在春季达到最小值。MBC季节性的这种纬度变化归因于土壤温度、土壤湿度和底物可用性的相互作用。MBC的季节性与异养呼吸模式不一致，这表明在这种分辨率下，用MBC作为微生物活动的指标是不合适的。这项研究强调了在微生物模型中明确体现微生物生理学的必要性。环境和底物对微生物季节性的交互控制为在季节性尺度上更好地模拟生态系统功能时体现微生物机制提供了见解。
