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), a