No home-field advantage in litter decomposition from the desert to temperate forest

General description The dataset is related to the publication “No home-field advantage in litter decomposition from the desert to temperate forest”, by van den Brink et al. 2023 in Functional Ecology. The study aimed at testing the home-field advantage hypothesis in litter decomposition along a climate gradient in Chile. Thus, the dataset comprises litter mass loss data from a translocation experiment with 20 litter species from four study sites (arid, semi-arid, Mediterranean and temperate), where each species was set to decompose in each of the study sites. In addition, the study used the ratios nitrogen to potassium loss (N/K loss) and phosphorus to potassium loss (P/K loss) to account for microbial breakdown (N and P loss) vs. physical leaching (K loss). Therefore, the dataset also contains the nutrient ratios for each mass loss data. The data of mass loss, N/K and P/K loss were used to calculate the litter ability, soil community ability and home-field effect according to the model presented by Keiser et al. (2014). The information used to run the mentioned model is also included in the dataset. The Excel file contains two sheets, the first one with the important metadata, and the second one contains the full data. General methods Five abundant and representative plant species per site were selected for the experiment. From those species, freshly senesced leaves were handpicked, while still attached to the plants during the dry season preceding the experiment (December 2016-January 2017). Litter was oven-dried at only 45°C for 48h. Five subsamples per litter species were separated from this initial litter and analyzed to determine initial element contents (C, N, P, K) per species. The initial element concentration was averaged at the species level. 1, 2 or 2.5 (±0.005) g of litter of each litter species were bagged in a 2-mm polyester mesh of 10x10cm. Litter bags from all species were then fully reciprocally translocated across the four study sites (20 species * 6 replicate plots * 4 sites) in early May 2017 (late autumn in the southern hemisphere). Bags were placed on top of the mineral soil or the organic layer (if present). The experiment was protected against animals with a poultry-wire mesh cage. All litterbags were retrieved after 12 months, placed in individual paper bags and the remaining litter was weighed after drying at 45°C for 48 h or until constant dry weight. For each sample, the percentage of litter mass loss was calculated as 100*(M0-Mt)/M0, where M0 is the initial dry mass of a sample and Mt is the remaining dry mass after 12 months of decomposition. The remaining litter from each litter bag was stored in individual paper bags and used for further elemental analyses. The litter was carefully cleaned and mineral soil particles were removed before analysis. Each litter sample was homogenized with a planet ball mill (Pulverisette 5, Fritsch Idar-Oberstein, Germany). The samples were not washed prior to the analysis to avoid loss of leachable elements such as K. Total C and N concentrations were measured by a CNS elemental analyser (Vario EL III, Elementar Analysensysteme GmbH, Langenselbold, Germany), and were used to calculate C/N mass ratios. For details regarding detection limits and quality controls please refer to the Supplementary Data of the publication. To determine the concentrations of potassium (K) and phosphorus (P), litter samples were dissolved by an acid pressure digestion system (Loftfield PDS-6, Loftfield Analytical Solutions, Neu Eichenberg, Germany). All vessels used were soaked in 10% HCl overnight and rinsed with Millipore water prior to use. Homogenized sample material (target weight: 0.05g) was transferred into Teflon pressure beakers before adding 4mL HNO3 conc. (65%, Merck KGaA, p.a. ≥ 98%). After heating for seven hours at 180°C, digestion solutions were filtered (MN 619 G¼ Ø185 mm, Macherey-Nagel, Düren, Germany) and diluted with Millipore water (Synergy UV ultrapure, Millipore) to a final volume of 50 ml. Digestions were analyzed by an inductively coupled plasma optical emission spectrometer (ICP-OES Optima 5300 DV, PerkinElmer, Wellesley USA) according to EN ISO 11885. Concentrations of P and K (mg kg-1) were calculated and corrected for recovery rates of the certified reference material BCR®-129 (hay powder, Institute for Reference Materials and Measurements). Similarly, the final element mass (mg) of a sample was calculated from the respective element concentration and the sample weight. The percentage of relative change in element content (K loss (%), N loss (%) and P loss (%)) for a sample was calculated as 100*(averaged initial element mass - final element mass) / averaged initial element mass. Later, the ratios N/K loss and P/K loss were calculated. K loss represents pure leaching effects, typically occurring at the very beginning of the decomposition process (Laskowski et al. 1995). N and P losses representing partially leaching, partially microbial breakdown. The ratios N/K loss and P/K loss, therefore, give an estimate of microbial breakdown, as they standardize N and P losses for leaching effects. Across sites (i.e., across the precipitation gradient), an increase in the ratios represents higher microbial breakdown, as the ratios are standardized for precipitation influence by the precipitation-dependent element (K). For more details on the methodology, please refer to the main manuscript and supplementary material associated to this dataset.

数据集概况
本数据集关联于van den Brink等人2023年发表于《功能生态学（Functional Ecology）》的论文《从荒漠到温带森林：枯落物（litter）分解无生境优势效应》。该研究旨在检验智利沿气候梯度分布的枯落物分解的生境优势假说（home-field advantage hypothesis）。因此，本数据集包含来自一项互换移栽实验（translocation experiment）的枯落物质量损失数据：实验涵盖4个研究样地（干旱区、半干旱区、地中海气候区与温带区）的20种枯落物物种，所有物种均在全部4个样地中开展分解实验。此外，本研究采用氮流失与钾流失比值（N/K流失比）、磷流失与钾流失比值（P/K流失比），以区分微生物分解过程（对应氮、磷流失）与物理淋溶过程（对应钾流失）。因此，本数据集同时包含对应每一项质量损失数据的养分比值数据。基于Keiser等人2014年提出的模型，本数据集的质量损失、N/K与P/K流失数据可用于计算枯落物分解能力、土壤群落分解能力与生境优势效应。运行该模型所需的相关参数信息也已收录于本数据集。本数据集的Excel文件包含两个工作表：第一个工作表存储核心元数据，第二个工作表存储完整实验数据。

实验方法概述
本实验在每个研究样地选取5种优势且具有代表性的植物物种。在实验前期的旱季（2016年12月—2017年1月），人工采集仍附着于植株上的新鲜衰老叶片。将采集的枯落物置于45℃烘箱中烘干48小时。从每份初始枯落物中分出5份子样本，用于测定各物种的初始元素含量（碳C、氮N、磷P、钾K），并在物种水平上对初始元素浓度取平均值。称取1、2或2.5g（误差±0.005g）各物种的枯落物，装入10cm×10cm、孔径2mm的聚酯网袋中。2017年5月初（南半球晚秋），将所有物种的枯落物网袋进行完全互换移栽，跨4个研究样地部署（20个物种×6个重复样方×4个样地）。将网袋放置于矿质土壤表层或有机层（若存在）。实验区域采用家禽铁丝网笼进行动物防护。12个月后回收所有枯落物网袋，分装于独立纸袋中，在45℃下烘干48小时或至干重恒定后，称量残留枯落物质量。每份样本的枯落物质量损失率计算公式为：100×(M0−Mt)/M0，其中M0为样本初始干重，Mt为分解12个月后的残留干重。每份网袋的残留枯落物均单独分装于纸袋，用于后续元素分析。分析前需仔细清理枯落物，去除矿质土壤颗粒。采用行星式球磨机（Pulverisette 5，德国Fritsch Idar-Oberstein公司）对每份枯落物样本进行均质化处理。分析前不洗涤样本，以避免钾等可淋溶元素的流失。采用碳氮硫元素分析仪（CNS elemental analyser，Vario EL III，德国Elementar Analysensysteme GmbH公司，Langenselbold）测定总碳和总氮浓度，并据此计算碳氮比（C/N）。关于检测限与质量控制的详细信息，请参阅该论文的补充数据。为测定钾（K）与磷（P）浓度，采用酸压消解系统（Loftfield PDS-6，德国Loftfield Analytical Solutions公司，Neu Eichenberg）对枯落物样本进行消解。所有实验容器均先用10%盐酸浸泡过夜，再用密理博超纯水（Millipore water）冲洗后备用。称取目标重量0.05g的均质化样本，置于聚四氟乙烯压力消解杯中，加入4mL浓硝酸（65%，德国Merck KGaA公司，分析纯≥98%）。在180℃下加热7小时后，将消解液过滤（MN 619 G¼，直径185mm，德国Macherey-Nagel公司，Düren），并用密理博超纯水（Synergy UV超纯水系统）定容至50mL。采用电感耦合等离子体发射光谱仪（ICP-OES Optima 5300 DV，美国PerkinElmer公司，Wellesley）按照EN ISO 11885标准对消解液进行分析。计算磷与钾的浓度（单位mg kg-1），并通过标准参考物质BCR®-129（干草粉，欧盟参考材料与测量研究所）的回收率进行校正。同理，根据各元素浓度与样本重量计算样本的最终元素质量（单位mg）。每份样本的元素含量相对变化百分比（钾流失率%、氮流失率%与磷流失率%）计算公式为：100×(平均初始元素质量−最终元素质量)/平均初始元素质量。随后计算N/K流失比与P/K流失比。钾流失代表纯物理淋溶效应，通常发生在分解过程的初始阶段（Laskowski等人1995）。氮与磷流失则同时包含淋溶与微生物分解两个过程。因此，N/K与P/K流失比可用于估算微生物分解程度，因为该比值已对淋溶效应导致的氮、磷流失进行了标准化校正。在不同样地（即沿降水梯度）中，该比值越高代表微生物分解程度越强，因为该比值以降水依赖型元素钾为基准，校正了降水对流失过程的影响。关于实验方法的更多细节，请参阅本数据集关联的论文正文与补充材料。