Department of Environmental and Biological Sciences, University of Eastern Finland, Joensuu campus, 80101 Joensuu, Finland.
Collaborative Innovation Center of Sustainable Forestry in China, College of Forestry, Nanjing Forestry University, 210037 Nanjing, China.
FEMS Microbiol Ecol. 2022 Jul 21;98(8). doi: 10.1093/femsec/fiac074.
Microbial communities often possess enormous diversity, raising questions about whether this diversity drives ecosystem functioning, especially the influence of diversity on soil decomposition and respiration. Although functional redundancy is widely observed in soil microorganisms, evidence that species occupy distinct metabolic niches has also emerged. In this paper, we found that apart from the environmental variables, increases in microbial diversity, notably bacterial diversity, lead to an increase in soil C emissions. This was demonstrated using structural equation modelling (SEM), linking soil respiration with naturally differing levels of soil physio-chemical properties, vegetation coverage, and microbial diversity after fire disturbance. Our SEMs also revealed that models including bacterial diversity explained more variation of soil CO2 emissions (about 45%) than fungal diversity (about 38%). A possible explanation of this discrepancy is that fungi are more multifunctional than bacteria and, therefore, an increase in fungal diversity does not necessarily change soil respiration. Further analysis on functional gene structure suggested that bacterial and fungal diversities mainly explain the potential decomposition of recalcitrant C compare with that of labile C. Overall, by incorporating microbial diversity and the environmental variables, the predictive power of models on soil C emission was significantly improved, indicating microbial diversity is crucial for predicting ecosystem functions.
微生物群落通常具有巨大的多样性，这引发了一个问题，即这种多样性是否驱动着生态系统的功能，特别是多样性对土壤分解和呼吸的影响。尽管土壤微生物中广泛存在功能冗余现象，但也有证据表明物种占据了不同的代谢生态位。在本文中，我们发现，除了环境变量外，微生物多样性的增加，特别是细菌多样性的增加，会导致土壤 C 排放的增加。这是通过结构方程模型（SEM）来证明的，该模型将土壤呼吸与火灾干扰后自然存在的土壤理化性质、植被覆盖度和微生物多样性的不同水平联系起来。我们的 SEM 还表明，包括细菌多样性在内的模型解释了更多的土壤 CO2 排放变化（约 45%），而真菌多样性（约 38%）则解释了较少的变化。造成这种差异的一个可能解释是，真菌比细菌具有更多的多功能性，因此，真菌多样性的增加不一定会改变土壤呼吸。对功能基因结构的进一步分析表明，细菌和真菌多样性主要解释了对难分解 C 的潜在分解作用，而不是对易分解 C 的潜在分解作用。总的来说，通过纳入微生物多样性和环境变量，模型对土壤 C 排放的预测能力得到了显著提高，这表明微生物多样性对预测生态系统功能至关重要。
