Data from: Plant functional groups regulate soil respiration responses to nitrogen addition and mowing over a decade

1. Nitrogen (N) deposition and land-use practice (e.g. mowing) could have profound effects on soil respiration. However, the changes in other ecosystem components, such as plant functional groups (PFGs), may control soil carbon (C) efflux response to long term global change. 2. A 10-year (2005-2014) field experiment was conducted with both N addition (10g N m-2 yr-1) and mowing (once a year) in a northern Chinese temperate grassland. We collected continuous data on soil respiration over 10 years accompanied with data on abiotic and biotic factors, and attempted to determine (i) the temporal variation in soil respiration and its responses to N addition and mowing, (ii) the regulation of soil respiration by PFGs and the underlying long-term mechanisms of control. 3. Soil respiration varied significantly among years. This was mainly caused by changes in precipitation pattern (e.g. frequency and distribution) during the growing-season rather than total rainfall. N addition significantly suppressed soil respiration by 10.4% whereas mowing stimulated it by 8.4% over the 10 years. The interaction of N addition with mowing had little effect on soil respiration. However, the significant effects of both N addition and mowing appeared only in the third year and thereafter, indicating the differences between long- and short-term responses. These long-term effects of N addition and mowing were mainly caused by changes in the PFGs of covers (e.g. grasses and forbs) and in soil pH rather than in soil microclimate. Forb-dominant patches had greater soil respiration than grass patches owing to their higher litter quality and photosynthetic capacity. 4. Our results highlight that shifts in aboveground plant community could play an important role in regulating soil respiration responses to N addition and mowing in the long-term. This is potentially important for improving our understanding of the link between above- and belowground ecological processes.

1. 氮沉降（Nitrogen deposition）与土地利用方式（如刈割）可对土壤呼吸（soil respiration）产生深远影响。然而，其他生态系统组分（如植物功能群（Plant Functional Groups, PFGs））的变化，或可调控土壤碳（C）排放对长期全球变化的响应。2. 本研究在中国北方温带草原开展了为期10年（2005-2014年）的野外控制实验，设置了氮添加（10g N m⁻² yr⁻¹）与每年1次刈割两个处理。我们连续收集了10年间的土壤呼吸观测数据，并同步获取了非生物与生物因子数据，旨在明确：①土壤呼吸的时间动态及其对氮添加与刈割的响应；②植物功能群对土壤呼吸的调控作用及其潜在的长期调控机制。3. 土壤呼吸在不同年份间存在显著差异，其主导驱动因子为生长季内降水格局（如降水频率与空间分布）的变化，而非总降雨量。10年整体观测结果显示，氮添加显著抑制了土壤呼吸（降幅达10.4%），而刈割则使其提升8.4%；氮添加与刈割的交互作用对土壤呼吸无显著影响。不过，氮添加与刈割的显著效应仅在实验第3年及之后才显现，这体现了短期与长期响应的差异。氮添加与刈割的上述长期效应，主要由地表覆盖植物功能群（如禾草与杂类草）的变化与土壤pH值改变所驱动，而非土壤微气候。相较于禾草斑块，以杂类草为优势的斑块土壤呼吸水平更高，这源于其更高的凋落物质量与光合能力。4. 本研究结果凸显，地上植物群落的结构转变在长期尺度上调控土壤呼吸对氮添加与刈割的响应过程中发挥着关键作用。这一发现对于增进我们对地上与地下生态过程间关联的理解具有重要价值。