Dataset for estimate fine root biomass in ecotone forests on the eastern of Maracá Island, northern Brazilian Amazonia

The dataset provides information on fine root biomass (2-20mm ; 1m in depth) associated to edaphic factors (soil texture and fertility) in ecotone forests located on the eastern of Maracá Island, a fluvial island integrated to the Maracá Ecological Station, state of Roraima, northern Brazilian Amazonia. This area represents an ecotone zone of the southern region of the Guyana Shield, which is dominated by mosaics of ombrophilous and seasonal forests in contact with savanna areas. Our sampling took into consideration 30 permanent plots located in the PPBio (Biodiversity Research Program) 25-km2 research grid installed in the eastern of Maracá Island. The fieldwork was carried in July and October 2015 when we collected two soil cores (sub-samples) 1 m in depth for each plot. Each soil core was composed by 10 sections of 10 cm in length (000-010 cm; … ; 090-100 cm). All fine root (2-20 mm) found in each section was classified by diameter categories (2-5 mm; 5-10mm; 10-20mm), dried in electric stove (100±3oC) and weighted (0,0001g). Soil analysis were performed for each depth section taking into account a composite sample derived from both soil cores. We used the soil analysis methodology adopted by Embrapa (Embrapa. 2009. Manual de análises químicas de solos, plantas e fertilizantes. Embrapa Informação Tecnológica, 2. ed. rev. ampl. Brasília-DF. 627 p). Our dataset is presented in two files: (i) soil_analysis - sampling units codes (plotID) and their geographical reference (UTM, SAD69, Zone 20), associated with altitude (m a.s.l.), drainage (well/poor), section depth (cm), and soil analysis (mean of the edaphic variables for each section - texture, fertility, soil bulk density); (ii) fine_root – fine root biomass (g) for each soil section by root diameter category (2-5 mm; 5-10mm; 10-20mm), sampling date and sub-sample number. This dataset was supported by institutional project PPI/INPA 015/122 (Ecologia e manejo de savannas e florestas de Roraima). The Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq - Brazil) provided a fellowships for R.I. Barbosa (CNPq 304204/2015-3) and M.T. Nascimento (CNPq 308352/2015-7). L.C.S. Carvalho was supported by a fellowship from Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES/PNPD). Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio) provided authorization for the study. This dataset is also available on the DataONE website (https://search.dataone.org/view/PPBioAmOc.135.9), as well as the soil bulk density data (https://search.dataone.org/view/PPBioAmOc.114.5).本数据集记录了巴西亚马逊北部罗赖马州马拉卡岛东部过渡带森林中，直径2-20mm、深度达1m的细根生物量与土壤因子（土壤质地与肥力）的关联信息。马拉卡岛为并入马拉卡生态站的河成岛，该区域属于圭亚那盾地南部过渡带，以常绿雨林与季节性森林镶嵌分布、毗邻稀树草原的群落景观为主。本研究采样基于PPBio（生物多样性研究计划，Biodiversity Research Program）在马拉卡岛东部布设的25km²研究网格内的30个永久样地开展。野外数据采集工作于2015年7月与10月完成，每个样地采集2个深度1m的土芯作为子样本。每个土芯被划分为10段，每段长度为10cm（000-010cm；……；090-100cm）。从每段土芯中分离得到直径2-20mm的细根，按直径分级为2-5mm、5-10mm、10-20mm三个类别，随后置于100±3℃的电热烘干炉中烘干至恒重，并用精度0.0001g的天平称重。针对每个土层深度段，以两个土芯的混合样本开展土壤理化分析，分析方法采用巴西农业研究公司（Embrapa）2009年出版的《土壤、植物与肥料化学分析手册》（第2版修订扩充版，巴西利亚-DF，共627页）。本数据集包含两个数据文件：(i) 土壤分析表（soil_analysis）：包含采样单元编码（样地ID）、地理坐标（UTM投影，SAD69坐标系，20带）、海拔（m a.s.l.，海拔基准面以上米数）、排水状况（良好/较差）、土层深度（cm）以及各土层土壤质地、肥力、容重等土壤因子的均值数据；(ii) 细根生物量表（fine_root）：包含各土层按直径分级的细根生物量（单位：g）、采样日期以及子样本编号。本数据集得到PPI/INPA 015/122机构项目（罗赖马州稀树草原与森林生态学及管理）的支持。巴西国家科学技术发展委员会（CNPq）为R.I. Barbosa（CNPq 304204/2015-3）与M.T. Nascimento（CNPq 308352/2015-7）提供了研究奖学金。L.C.S. Carvalho得到了巴西高等教育人员发展协调局（CAPES/PNPD）的奖学金支持。巴西奇科·门德斯生物多样性保护研究所（ICMBio）为本次研究提供了野外研究许可。本数据集及土壤容重数据可分别通过DataONE数据平台的以下链接获取：https://search.dataone.org/view/PPBioAmOc.135.9 与 https://search.dataone.org/view/PPBioAmOc.114.5。