LeafQualityDatabase.xlsx

This data set comes from the research carried out by Sena et al. <em>Study sites</em> We studied riparian forests of low-order streams located inside preserved areas (1st-3rd order reaches; hereafter sites) in three South American biomes: (i) Amazon (2 sites), (ii) Cerrado (3 sites), and (iii) Atlantic Forest (6 sites). Sites in the Amazon were located in nonflooded forests in the central and northern Amazon with equatorial climate, tall trees, and evergreen canopy. Cerrado sites were located in the Brazilian Central Plateau with a tropical wet‒dry climate, where streams drain through dense corridors of evergreen forests known as gallery forests. Atlantic Forest sites were located in inland and coastal areas of Brazil, spanning a large latitudinal gradient in climate (~ 30 degrees of latitude), from subtropical to equatorial, comprising tropical and subtropical rainforests, Araucaria forests and seasonal tropical forests. The dataset analyzed comprises information from litter for 68 plant species collected across 11 riparian forests within preserved areas (reference conditions) of three neotropical biomes within the tropics: the Amazon (Cantá and Manaus), the Cerrado (Patrocínio, Brasília and Palmas) and the Atlantic Forest (Erechim, Florianópolis, Varzedo, Parnamirim, Palotina and Santa Leopoldina). We analyzed seven chemical traits (%C, %N, %P, %Phenols, C:N, C:P, and N:P ratios) and two physical traits of the litter (toughness and specific leaf area). <em>Field sampling protocol</em> The sampling sites consisted of a 100 m stretch of each forest stream with the most extensive vegetation cover and without apparent anthropogenic impact. Litterfall was sampled using suspended litter traps (1 m2, 10 mm mesh) fixed 1.5 m high on both streambanks to optimize the sampling effort. Fallen leaves were collected every 15 days to avoid leaching or decomposition. Recently fallen leaves were sampled during the period of maximum litterfall in the year, which was defined according to recent literature (Tonin et al., 2017) and/or the expertise of local researchers. Litter was transported to the laboratory and oven-dried (60 °C, 72 h) for chemical analyses; litter used to determine specific leaf area (SLA) and toughness was air-dried only. All litter samples from the same site were pooled and homogenized. Then, the litter for the 5-10 most representative tree species in terms of dry mass were separated and identified to the lowest possible taxonomic level. <em>Physical and chemical characterization of litter traits</em> Twenty grams of litter from each was ground in a vibratory ball mill (Fritsch Pulverisette, Model 0, Idar-Oberstein, Germany) for the chemical analyses. The C and N concentrations (% of dry mass) were analyzed by total combustion (950 °C) in an elemental analyzer (Leco Instruments Ltda, Model Truspec CHN628, San José, Michigan, USA). The P concentration was quantified spectrophotometrically (measuring absorbance at 882 nm) using the ascorbic acid method after combustion (550°C for 4 h) and digestion (with hydrochloric acid) of litter samples (Flindt et al., 2020). Total phenols were determined using the Folin-Ciocalteau method (Bärlocher &amp; Graça, 2020). All chemical analyses were run using triplicates of 100-mg portions of litter powder from each species. Entire leaves were used for the determination of SLA and toughness. SLA, a proxy for litter toughness (that is, higher SLA values are usually found for softer litter; Boyero et al., 2017), was estimated using 10-20 leaf discs (12 mm diameter) from different parts of the leaves and from different leaves of the same species. Each leaf disc was then weighed (0.01 mg) to determine its mass. SLA was obtained through the quotient of leaf disc area to leaf dry mass (in grams). Litter toughness was estimated with a penetrometer, which measures the pressure (in kgF cm-1) necessary to pierce the tissue of a leaf with a steel rod (1.55-mm diameter) (Boyero et al. 2011). The litter toughness of a species was the average of 10-20 measurements made on different leaves. <br> <br>

本数据集源自Sena等人开展的研究工作。
*研究样地*
我们对位于3个南美生物群系内保护区域中的低级别溪流河岸森林（1~3级河段，下称样地）开展了研究：(i) 亚马逊（Amazon）流域（2个样地）、(ii) 塞拉多（Cerrado）流域（3个样地），以及(iii) 大西洋森林（Atlantic Forest）流域（6个样地）。亚马逊样地位于亚马逊中部和北部的非泛滥森林，属赤道气候，拥有高大乔木与常绿冠层。塞拉多样地位于巴西中央高原，气候为热带干湿季型，溪流流经被称为长廊林（gallery forests）的常绿茂密林带。大西洋森林样地分布于巴西内陆与沿海区域，跨越约30个纬度的广阔气候梯度（从亚热带至赤道），涵盖热带与亚热带雨林、南洋杉林（Araucaria forests）与季节性热带林。
本数据集的分析数据涵盖68种植物的枯落物信息，采集自热带地区3个新热带生物群系保护区域（参照生境）内的11处河岸森林：亚马逊流域（坎塔（Cantá）与马瑙斯（Manaus））、塞拉多流域（帕特罗西尼奥（Patrocínio）、巴西利亚（Brasília）与帕尔马斯（Palmas））以及大西洋森林流域（埃雷希姆（Erechim）、弗洛里亚诺波利斯（Florianópolis）、瓦尔泽杜（Varzedo）、帕尔纳里米（Parnamirim）、帕洛蒂纳（Palotina）与圣利奥波尔杜（Santa Leopoldina））。我们分析了7项化学性状：碳占比（%C）、氮占比（%N）、磷占比（%P）、酚类物质含量（%Phenols）、碳氮比（C:N）、碳磷比（C:P）与氮磷比（N:P），以及2项枯落物物理性状：韧性（toughness）与比叶面积（specific leaf area, SLA）。
*野外采样方案*
采样样地为每条森林溪流中植被覆盖最广泛、无明显人为干扰的100米河段。枯落物收集采用悬挂式枯落物收集器（面积1 m²，网孔10 mm），固定于溪流两岸1.5 m高处以优化采样效率。每15天收集一次凋落叶片，避免淋溶或分解。在年度枯落物最大掉落期采集新近凋落的叶片，该时段的确定参考了近期文献（Tonin et al., 2017）及当地研究人员的专业经验。枯落物被运送至实验室后，置于60℃烘箱中烘干72小时以开展化学分析；用于测定比叶面积（SLA）与韧性的枯落物仅需风干。同一样地的所有枯落物样品被混合均质。随后，按干重占比选取5~10种最具代表性的乔木物种，分离并鉴定至尽可能低的分类学层级。
*枯落物性状的理化表征*
每份样品取20 g枯落物，在振动球磨机（Fritsch Pulverisette，型号0，德国伊达尔-奥伯斯坦）中研磨以用于化学分析。碳、氮浓度（占干重百分比）通过元素分析仪（Leco Instruments Ltda，型号Truspec CHN628，美国密歇根州圣何塞）在950℃下总燃烧法测定。磷浓度采用抗坏血酸法，先将枯落物样品在550℃下灼烧4小时并经盐酸消解后，通过分光光度法在882 nm波长处测定吸光度进行定量（Flindt et al., 2020）。总酚类物质含量采用福林-酚法（Folin-Ciocalteau method）测定（Bärlocher & Graça, 2020）。所有化学分析均采用每份100 mg的枯落物粉末平行测定3次。采用完整叶片测定比叶面积（SLA）与韧性。比叶面积（SLA）作为枯落物韧性的替代指标（即较高的SLA值通常对应更柔软的枯落物；Boyero et al., 2017），通过取自不同叶片不同部位的10~20个叶圆盘（直径12 mm）估算。随后称量每个叶圆盘的质量（精度0.01 mg）。SLA通过叶圆盘面积与叶干重（以克为单位）的比值计算得到。枯落物韧性通过针入式硬度计（penetrometer）测定，该仪器通过直径1.55 mm的钢杆刺穿叶片组织所需的压力（单位为kgF·cm⁻¹）来量化韧性（Boyero et al. 2011）。某一物种的枯落物韧性为在不同叶片上测得的10~20次测量结果的平均值。
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