Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA.
Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA, USA.
Nat Commun. 2023 Apr 19;14(1):2227. doi: 10.1038/s41467-023-37862-6.
Lignin is an abundant and complex plant polymer that may limit litter decomposition, yet lignin is sometimes a minor constituent of soil organic carbon (SOC). Accounting for diversity in soil characteristics might reconcile this apparent contradiction. Tracking decomposition of a lignin/litter mixture and SOC across different North American mineral soils using lab and field incubations, here we show that cumulative lignin decomposition varies 18-fold among soils and is strongly correlated with bulk litter decomposition, but not SOC decomposition. Climate legacy predicts decomposition in the lab, and impacts of nitrogen availability are minor compared with geochemical and microbial properties. Lignin decomposition increases with some metals and fungal taxa, whereas SOC decomposition decreases with metals and is weakly related with fungi. Decoupling of lignin and SOC decomposition and their contrasting biogeochemical drivers indicate that lignin is not necessarily a bottleneck for SOC decomposition and can explain variable contributions of lignin to SOC among ecosystems.
木质素是一种丰富而复杂的植物聚合物，可能会限制凋落物分解，但木质素有时是土壤有机碳（SOC）的次要组成部分。考虑到土壤特性的多样性，可能会调和这一明显的矛盾。通过实验室和野外培养，追踪不同北美矿质土壤中木质素/凋落物混合物和 SOC 的分解，我们发现，木质素的累积分解在土壤中变化了 18 倍，与批量凋落物分解密切相关，但与 SOC 分解无关。气候遗产可以预测实验室中的分解，而氮素供应的影响与地球化学和微生物特性相比微不足道。木质素分解与一些金属和真菌类群增加有关，而 SOC 分解则与金属减少有关，与真菌的关系较弱。木质素和 SOC 分解的解耦及其相反的生物地球化学驱动因素表明，木质素不一定是 SOC 分解的瓶颈，并且可以解释木质素在不同生态系统中对 SOC 的可变贡献。
