The long-standing assumption that aboveground plant litter inputs have a substantial influence on soil organic carbon storage (SOC) and dynamics has been challenged by a new paradigm for SOC formation and persistence. We tested the importance of plant litter chemistry on SOC storage, distribution, composition, and age by comparing two highly contrasting ecosystems: an old-growth coast redwood (Sequoia sempervirens) forest, with highly aromatic litter, and an adjacent coastal prairie, with more easily decomposed litter. We hypothesized that if plant litter chemistry was the primary driver, redwood would store more and older SOC that was less microbially processed than prairie. Total soil carbon stocks to 110 cm depth were higher in prairie (35 kg C m−2) than redwood (28 kg C m−2). Radiocarbon values indicated shorter SOC residence times in redwood than prairie throughout the profile. Higher amounts of pyrogenic carbon and a higher degree of microbial processing of SOC appear to be instrumental for soil carbon storage and persistence in prairie, while differences in fine-root carbon inputs likely contribute to younger SOC in redwood. We conclude that at these sites fire residues, root inputs, and soil properties influence soil carbon dynamics to a greater degree than the properties of aboveground litter.

中文翻译：

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土壤碳库与地上枯落物输入以及古老森林和邻近草原的化学成分无关

长期以来的假设是，地上植物凋落物输入对土壤有机碳储存（SOC）和动态具有重大影响，这一假设受到了 SOC 形成和持久性新范式的挑战。我们通过比较两个高度对比的生态系统来测试植物凋落物化学对 SOC 存储、分布、组成和年龄的重要性：古老的海岸红杉（长绿红杉）森林，有高度芳香的垃圾，以及邻近的沿海草原，有更容易分解的垃圾。我们假设，如果植物凋落物化学是主要驱动因素，那么红木会储存更多、更古老的 SOC，而这些 SOC 的微生物处理程度比草原少。草原 110 厘米深度的土壤总碳储量较高（35 kg C m−2）比红木（28 kg C m−2）。放射性碳值表明，在整个剖面中，红杉中的 SOC 停留时间比草原短。较高量的热解碳和较高程度的 SOC 微生物处理似乎有助于草原土壤碳储存和持久性，而细根碳输入的差异可能有助于红木中较年轻的 SOC。我们得出的结论是，在这些地点，火灾残留物、根系输入和土壤特性对土壤碳动态的影响程度大于地上枯落物的特性。