Cellulose is an essential component of plant cell walls, and one of the major constituents of soil organic matter. Decomposition of cellulose, mediated by microorganisms, is critical to the sustainable development of arable soils. However, how exogenous cellulose addition, as a surrogate for organic material amendment, influences the diversity and community compositions of soil microorganisms and their network complexity remains largely unknown. To bridge this knowledge gap, we conducted a microcosm experiment incubated with soils that had been subjected to long-term mineral or organic fertilization. Cellulose addition increased the cumulative CO₂ emission in all treatments, with the highest value found in the pig manure amended soils. Cellulose addition significantly reduced the alpha diversity of bacteria and fungi across all fertilization treatments, with a more pronounced effect observed for fungi. Moreover, cellulose addition strongly altered bacterial community structure by increasing the relative abundance of copiotrophic bacteria such as Actinobacteria and Proteobacteria while reducing that of oligotrophic bacteria (e.g., Chloroflexi). Compared with no-fertilizer treatment, the influence of cellulose addition on bacterial and fungal community structure was stronger in long-term mineral or organic fertilized soils. Cellulose addition altered the relative abundance of bacterial and fungal functional groups by generally enriching microbes involved in chemoheterotrophy and suppressing those involved in methylotrophy, pathotroph, saprotroph-symbiotroph, and saprotroph-pathotroph. In addition, cellulose addition decreased soil microbial complexity and the number of potential keystone species, but did not change the key role of Chloroflexi in soil microbial network. Overall, our results demonstrated that cellulose addition decreased soil microbial diversity and network complexity, with possible short-term negative consequences for ecosystem functioning in Ultisols.

纤维素是植物细胞壁的重要组成部分，也是土壤有机质的主要成分之一。由微生物介导的纤维素分解对于耕地的可持续发展至关重要。然而，作为有机物质改良替代物的外源纤维素添加如何影响土壤微生物的多样性和群落组成及其网络复杂性在很大程度上仍然未知。为了弥合这一知识鸿沟，我们进行了一项微观实验，在土壤中进行了长期的矿物或有机施肥。添加纤维素增加了累积 CO ₂在所有处理中的排放量，在猪粪改良土壤中发现的最高值。添加纤维素显着降低了所有施肥处理中细菌和真菌的 alpha 多样性，对真菌的影响更为明显。此外，纤维素的添加通过增加嗜养菌（如放线菌和变形菌）的相对丰度，同时减少贫养菌（如 Chloroflexi）的相对丰度，极大地改变了细菌群落结构。与不施肥处理相比，长期施用矿物质或有机肥的土壤中，纤维素添加对细菌和真菌群落结构的影响更强。添加纤维素通常通过富集参与化学异养的微生物并抑制参与甲基营养、致病菌、腐生-共生体和腐生-致病菌的微生物来改变细菌和真菌官能团的相对丰度。此外，纤维素的添加降低了土壤微生物的复杂性和潜在关键物种的数量，但没有改变 Chloroflexi 在土壤微生物网络中的关键作用。总体而言，我们的结果表明，添加纤维素降低了土壤微生物多样性和网络复杂性，可能对 Ultisol 中的生态系统功能产生短期负面影响。添加纤维素降低了土壤微生物的复杂性和潜在关键物种的数量，但没有改变 Chloroflexi 在土壤微生物网络中的关键作用。总体而言，我们的结果表明，添加纤维素降低了土壤微生物多样性和网络复杂性，可能对 Ultisol 中的生态系统功能产生短期负面影响。添加纤维素降低了土壤微生物的复杂性和潜在关键物种的数量，但没有改变 Chloroflexi 在土壤微生物网络中的关键作用。总体而言，我们的结果表明，添加纤维素降低了土壤微生物多样性和网络复杂性，可能对 Ultisol 中的生态系统功能产生短期负面影响。