Data from: Home-field advantages of litter decomposition increase with increasing N deposition rates: a litter and soil perspective

1. Differences in litter quality and in soil microbial community composition can influence the litter decomposition and “home-field advantage” (HFA). However, our knowledge about the relative role of litter and soil characteristics on litter decomposition and HFA effects is still limited, especially under long-term N deposition. 2. We collected soil and two types of litter (monospecific and mixed species litter) from five replicate plots from a long-term N-deposition field experiment with seven N-addition treatments (0, 2, 5, 10, 15, 20, 50 g N m-2 yr-1). We examined the effects of N-addition on litter quality and soil characteristics. We then carried out a three-pronged microcosm decomposition experiment with (i) litter from different N-addition treatments decomposed on a standard field soil; (ii) standard litter decomposed on soils from the different N-addition treatments; and (iii) litter decomposed on soil from the same N-addition treatment plot. 3. Decomposition of litter on standard soil was influenced strongly by the N-addition treatment, but did not consistently decrease or increase with increasing N-addition rates. Instead, decomposition of standard litter on soils collected from different N-addition treatments decreased with increasing rates of N-addition. Decomposition of litter on soil collected from the same plot increased with increasing N-addition rates. Soil characteristics explained more of the variation in litter decomposition than litter characteristics. 4. There was a clear HFA effect for litter decomposition; both from a litter and from a soil perspective. HFA effects increased when the dissimilarity in litter quality (N content and C: N ratio) increase among the different N-addition treatments and the soil effect was strongest at high N-addition rates. 5. N-addition influenced litter decomposition by changing both litter and soil characteristics. Importantly, N-addition decreased the capability of soils to decompose litter and it increased the home-field advantage effect indicating that soils decomposed local litter better than other litter, due to specialization in soil communities. Nitrogen deposition is an important threat to ecosystems worldwide and our study emphasizes that ecosystem functions such as decomposition can be greatly influenced by these global changes.

1. 凋落物质量与土壤微生物群落组成的差异，可对凋落物分解及**本土优势效应（home-field advantage, HFA）**产生影响。然而，当前学界对凋落物与土壤特性在凋落物分解及HFA效应中的相对作用认知仍较为有限，尤其是在长期氮沉降背景下。2. 本研究从一项包含7种氮添加处理（0、2、5、10、15、20、50 g N·m⁻²·yr⁻¹）的长期氮沉降野外试验的5个重复样地中，采集了土壤与两类凋落物（单物种凋落物与多物种混合凋落物）。我们分析了氮添加对凋落物质量及土壤特性的影响，随后开展了三组分微宇宙分解实验：① 将不同氮添加处理下获取的凋落物置于标准野外土壤中进行分解；② 将标准凋落物置于不同氮添加处理下的土壤中进行分解；③ 将凋落物置于同一样地的土壤中进行分解。3. 标准土壤上的凋落物分解受氮添加处理的影响显著，但并未随氮添加速率提升呈现持续降低或升高的趋势。与之相反，置于不同氮添加处理土壤上的标准凋落物分解率，随氮添加速率提升而下降；而同一样地土壤上的凋落物分解率，则随氮添加速率提升而升高。相较于凋落物特性，土壤特性对凋落物分解变异的解释度更高。4. 凋落物分解存在显著的HFA效应，这一效应可从凋落物与土壤两个维度得以体现。当不同氮添加处理间的凋落物质量（氮含量与碳氮比）差异增大时，HFA效应随之增强；且在高氮添加速率下，土壤因子对HFA的驱动作用最为显著。5. 氮添加通过改变凋落物与土壤特性，进而影响凋落物分解过程。值得注意的是，氮添加会降低土壤的凋落物分解能力，同时增强本土优势效应，这表明由于土壤群落的适应性特化，土壤对本土凋落物的分解效果优于外来凋落物。氮沉降是全球范围内生态系统面临的重要威胁之一，本研究强调，分解作用这类生态系统功能会受到此类全球环境变化的显著影响。