 Lignin is an abundant and complex plant polymer that can slow down the decomposition of litter, but it is often a minor component of soil organic carbon, SOC. Different soil conditions can account for this apparent contradiction. In laboratory experiments, lignin decomposition varied greatly among soils, while SOC decomposition was less affected by soil type. This suggests that lignin decomposition is more dependent on local environmental factors than SOC decomposition. Furthermore, climate history appears to be the main driver of lignin decomposition, while nutrients and microbes have only a small effect. These findings suggest that lignin is not necessarily a barrier to SOC decomposition and can help explain why lignin content varies widely among ecosystems. This article was authored by Wen Huan Huang, Wen Huan Yu, Bo Yi, and others.