Climate and land-use changes have altered both litter quality and quantity, with cascading impacts on soil respiration (SR). Soil extracellular enzymes (EEs) like cellulase and ligninase are crucial for deconstructing plant litter because they convert polymers into monomers. However, whether and how changes in litter inputs influence soil cellulase and ligninase activities as well as the implications for SR remain poorly understood. We conducted a global meta-analysis of 827 observations on the responses of SR and soil cellulase and ligninase activities to litter addition and litter removal. Litter addition significantly increased cellulase activity by 25 %, whereas litter removal decreased it by 26 %. Neither litter addition nor litter removal affected ligninase activity. Changes in cellulase activity correlated positively with SR under both litter addition and litter removal, but no such relationship was found for ligninase activity. These results indicate that changes in litter inputs affect SR primarily by affecting the microbial decomposition of readily decomposable rather than more structurally complex carbon pools. In addition, the effects of changes in litter inputs on cellulase activity decreased with treatment duration, suggesting that the long-term effects of changes in litter inputs on SR might be smaller than previously thought. Our results underscore the dominant role of cellulase in mediating the responses of SR to altered litter inputs. Integrating cellulase responses to altered litter inputs into Earth system models could improve the representation of microbial processes and refine the predictions of soil carbon dynamics.

中文翻译：

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在改变的凋落物输入下将土壤细胞外酶与土壤呼吸联系起来


气候和土地利用变化改变了凋落物的质量和数量，对土壤呼吸 （SR） 产生了级联影响。纤维素酶和木质素酶等土壤细胞外酶 （EE） 对于解构植物凋落物至关重要，因为它们将聚合物转化为单体。然而，凋落物输入的变化是否以及如何影响土壤纤维素酶和木质素酶活性以及对 SR 的影响仍然知之甚少。我们对 SR 和土壤纤维素酶和木质素酶活性对凋落物添加和凋落物清除的响应的 827 项观察结果进行了全球荟萃分析。凋落物添加使纤维素酶活性显着提高了 25%，而凋落物清除使其降低了 26%。凋落物添加和凋落物清除均未影响木质素酶活性。在凋落物添加和凋落物清除下，纤维素酶活性的变化与 SR 呈正相关，但木质素酶活性未发现这种关系。这些结果表明，凋落物输入的变化主要通过影响易于分解而不是结构更复杂的碳库的微生物分解来影响 SR。此外，凋落物输入变化对纤维素酶活性的影响随着处理持续时间的增加而降低，这表明凋落物输入变化对 SR 的长期影响可能比以前认为的要小。我们的结果强调了纤维素酶在介导 SR 对改变的凋落物输入的反应中的主导作用。将纤维素酶对改变的凋落物输入的反应整合到地球系统模型中，可以改善微生物过程的表示并改进土壤碳动力学的预测。