Both plant litter and roots are major sources of soil carbon (C) pools, however, the relative contributions of these two C input pathways to soil respiration, especially in different forest types, are largely unexplored, leading to a great uncertainty in estimating soil C sinks. As part of a field experiment with five-year (2016–2020) C input manipulations in three forests all between the subtropical and warm temperate region, this study was conducted to explore the responses of soil respiration to litter addition, litter removal, and root exclusion in a coniferous forest, a broadleaved forest, and a mixed broadleaf-conifer forest. Our results showed that litter addition enhanced soil respiration by 9.57 %, 15.5 %, and 24.5 % in the coniferous, broadleaved, and mixed forests, whereas litter removal decreased it by 4.06 % and 8.30 % in the coniferous and broadleaved forests across the five years due to the changes in soil microclimate and litter-derived C sources as well as a potential priming effect in the soil. Root exclusion reduced soil respiration in all the three forests, but its effect did not differ with that of litter removal, primarily attributing to the indistinctive deviation between these two C input pathways on soil microbial biomass. The influences of different C inputs on soil respiration varied with forest types, with interactions of root exclusion with litter manipulations occurring in the coniferous and broadleaved forests but additive effects of those in the mixed broadleaf-conifer forest. Our findings indicate different responses of soil respiration to plant litter and root manipulations in diverse forests, and imply that rational regulating of plant-derived C inputs can help to reduce soil C loss under climate change scenarios.

中文翻译：

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植物凋落物和根系碳输入的变化改变了气候过渡区 3 个不同森林的土壤呼吸


植物凋落物和根系都是土壤碳 （C） 库的主要来源，然而，这两种 C 输入途径对土壤呼吸的相对贡献，尤其是在不同的森林类型中，在很大程度上尚未得到探索，导致估计土壤碳汇存在很大的不确定性。作为在亚热带和暖温带地区之间的三个森林中进行五年 （2016-2020） C 输入操作的田间试验的一部分，本研究旨在探讨土壤呼吸对针叶林、阔叶林和阔叶针叶混交林中凋落物添加、凋落物清除和根排除的响应。我们的结果表明，由于土壤微气候和凋落物衍生的碳来源的变化以及土壤中潜在的启动效应，凋落物添加在五年内使针阔林的土壤呼吸增加了 9.57 %、15.5 % 和 24.5%，而凋落物清除使针阔林的土壤呼吸减少了 4.06 % 和 8.30%。根系排除减少了所有 3 种森林的土壤呼吸，但其效果与去除凋落物的效果没有差异，主要是由于这两个 C 输入途径对土壤微生物量的无差别偏差。不同碳输入对土壤呼吸的影响因森林类型而异，根排除与凋落物处理的相互作用发生在针阔林中，而阔叶针叶混交林中的相互作用则发生在加性效应中。我们的研究结果表明，在不同森林中，土壤呼吸对植物凋落物和根系操纵的反应不同，并意味着合理调节植物来源的 C 输入有助于减少气候变化情景下的土壤 C 损失。