Retaining harvest residues (HR) in the field is considered an option to recycle carbon (C) and nutrients in short-rotation plantations, but the fate of HR in the soil remains unclear. The effects of HR management and nitrogen (N) availability on soil organic matter (SOM) pools and microbial community structure of forest plantations represent a major knowledge gap. To fill this gap, we explored how management scenarios that differed in the amount and type of HR [removal of all residues (-R), residue retention without (+R/-B), or with bark (+R/+B)] and N availability [0 (-N) or 200 kg N ha^-1 (+N)] influenced microbial activity and structure and SOM fractions in a recently afforested grassland. Specifically, we measured HR decomposition, carbon dioxide efflux (respired CO₂), phospholipid fatty acid (PLFA), and determined changes in particulate (POM) and mineral-associated organic matter (MAOM) over 12 months using differences in δ¹³C natural abundance between Eucalyptus HR and grassland soils (δ¹³C ∼-28 ‰ and -13 ‰, respectively). Microbial respiration was stimulated by HR retention (+R). Bark retention reduced HR half-life by ∼70 days, on average, while N had little influence. Bacterial groups (Gram-positive and Gram-negative) were the primary decomposer of eucalypt HR, while Actinobacteria used more of the former soil organic carbon (SOC). +R/+B increased fungal biomarker PLFA concentration and fungal:bacterial ratio, suggesting a key role of Fungi in the fragmentation of woody HR. N influence on microbial community structure and SOM pools was dependent upon HR management. Retaining HR increased SOC concentrations, most significantly in the 0–1 cm soil depth and POM fraction, and when bark was included. +R/+B resulted in higher POM-C concentrations (up to +37%) and more depleted δ¹³C-POM compared with -R and +R/-B, respectively. Collectively, our results suggest it is feasible to increase POM-C and fungal abundance through HR management practices in the early stages of decomposition, which may potentially contribute to SOC stabilization in the long-term. Yet our findings remain to be tested in long-term studies, we provide quantitative evidence of the potential of a more conservative HR management to contribute to the sustainability of eucalypt plantations.

在田间保留收获残余物（HR）被认为是在短周期人工林中回收碳（C）和养分的一种选择，但是HR在土壤中的命运仍然不清楚。人力资源管理和氮（N）的可用性对人工林土壤有机质（SOM）库和微生物群落结构的影响是一个主要的知识差距。为了填补这一空白，我们探索了在HR的数量和类型[所有残留物的去除（-R），无残留物（+ R / -B）或有树皮（+ R / + B）的管理方案之间如何不同。 ]和N的利用率[0（-N）或200 kg N ha ^-1（+ N）]影响了最近造林的草地中的微生物活性，结构和SOM分数。具体来说，我们测量了HR分解，二氧化碳外排（呼吸的CO ₂类），磷脂脂肪酸（PLFA），并在微粒（POM）和矿物相关有机物确定的变化（MAOM）超过12个月使用δ差异¹³ ℃之间天然丰度桉树HR和草原土壤（δ ¹³C分别为-28‰和-13‰）。HR保留（+ R）刺激了微生物的呼吸。保留树皮平均可使HR半衰期减少约70天，而N几乎没有影响。细菌类（革兰氏阳性和革兰氏阴性）是桉树HR的主要分解剂，而放线菌则使用更多的前土壤有机碳（SOC）。+ R / + B增加了真菌生物标志物PLFA的浓度和真菌：细菌的比率，表明真菌在木质HR片段化中起关键作用。N对微生物群落结构和SOM库的影响取决于人力资源管理。保持HR会增加SOC浓度，最显着的是在0–1 cm的土壤深度和POM分数中，包括树皮在内。+ R / + B导致更高的POM-C的浓度（高达+ 37％）和更耗尽δ ¹³C-POM分别与-R和+ R / -B相比。总的来说，我们的结果表明，在分解的早期阶段通过人力资源管理实践来提高POM-C和真菌的丰度是可行的，这从长远来看可能有助于SOC稳定。然而，我们的发现仍有待长期研究检验，我们提供了定量证据，表明更保守的人力资源管理可能有助于桉树人工林的可持续发展。