Department of Bacterial Physiology, Institute of Microbiology, 17489 Greifswald, Germany.
Experimental Plant Ecology, Institute of Botany and Landscape Ecology, 17489 Greifswald, Germany.
Sci Total Environ. 2024 Aug 25;940:173480. doi: 10.1016/j.scitotenv.2024.173480. Epub 2024 May 23.
The rewetting of formerly drained peatlands can help to counteract climate change through the reduction of CO emissions. However, this can lead to resuming CH emissions due to changes in the microbiome, favoring CH-producing archaea. How plants, hydrology and microbiomes interact as ultimate determinants of CH dynamics is still poorly understood. Using a mesocosm approach, we studied peat microbiomes, below-ground root biomass and CH fluxes with three different water level regimes (stable high, stable low and fluctuating) and four different plant communities (bare peat, Carex rostrata, Juncus inflexus and their mixture) over the course of one growing season. A significant difference in microbiome composition was found between mesocosms with and without plants, while the difference between plant species identity or water regimes was rather weak. A significant difference was also found between the upper and lower peat, with the difference increasing as plants grew. By the end of the growing season, the methanogen relative abundance was higher in the sub-soil layer, as well as in the bare peat and C. rostrata pots, as compared to J. inflexus or mixture pots. This was inversely linked to the larger root area of J. inflexus. The root area also negatively correlated with CH fluxes which positively correlated with the relative abundance of methanogens. Despite the absence or low abundance of methanotrophs in many samples, the integration of methanotroph abundance improved the quality of the correlation with CH fluxes, and methanogens and methanotrophs together determined CH fluxes in a structural equation model. However, water regime showed no significant impact on plant roots and methanogens, and consequently, on CH fluxes. This study showed that plant roots determined the microbiome composition and, in particular, the relative abundance of methanogens and methanotrophs, which, in interaction, drove the CH fluxes.
曾经排干的泥炭地的重新湿润有助于通过减少 CO 排放来抵消气候变化。然而，由于微生物组的变化，这可能导致 CH 排放的恢复，有利于产生 CH 的古菌。植物、水文学和微生物组作为 CH 动态的最终决定因素是如何相互作用的，这仍然知之甚少。本研究使用中观模型，在一个生长季内，通过三种不同的水位（稳定高水位、稳定低水位和波动水位）和四种不同的植物群落（裸泥炭、薹草、灯芯草和它们的混合物），研究了微生物组、地下根系生物量和 CH 通量。结果发现，有植物和无植物的中观模型之间的微生物组组成存在显著差异，而植物物种身份或水位之间的差异则相对较弱。还发现泥炭的上层和下层之间存在显著差异，随着植物的生长，差异增加。到生长季末，与灯芯草或混合物相比，地下土层、裸泥炭和薹草盆中的产甲烷菌相对丰度更高。这与灯芯草较大的根面积呈负相关。根面积也与 CH 通量呈负相关，而 CH 通量与产甲烷菌的相对丰度呈正相关。尽管许多样本中缺乏或产甲烷菌丰度低，但产甲烷菌丰度的整合提高了与 CH 通量相关性的质量，并且产甲烷菌和产甲烷菌共同决定了结构方程模型中的 CH 通量。然而，水位对植物根系和产甲烷菌没有显著影响，因此对 CH 通量也没有显著影响。本研究表明，植物根系决定了微生物组组成，特别是产甲烷菌和产甲烷菌的相对丰度，它们相互作用，驱动 CH 通量。
