Soil analysis data for forest islands dispersed on savannas of Roraima, northern Brazilian Amazonia
The dataset provides information on soil texture and fertility for twelve forest islands (or forest fragments) dispersed on savannas of Roraima, northern Brazilian Amazonia. The sampled forest islands are representations of semideciduous seasonal forests with paleoclimatic origin naturally dispersed over a landscape with low altitude (~90 m a.s.l.). They are situated in a forest–savanna ecotone and have been exposed to frequent anthropogenic impact as selective logging and understory forest fire. The fieldwork was carried out between 2013-2014, when were taken soil cores from a profile to 100 cm depth, divided into six intervals (0–10, 10–20, 20–30, 30–40, 40–50, and 90–100 cm). The samples were arranged equidistantly along transects to represent the variability in texture and soil fertility between the edges and the interior (gradient of position) of each fragment (see details in Turcios et al. 2016. Soil charcoal as long-term pyrogenic carbon storage in Amazonian seasonal forests. Global Change Biology, 22: 190–197). The dataset is presented in three files: (i) study_site - a figure indicating location of the study area, (ii) soil_analysis_with gradient – a file with the identification of each sampling unit (forest island), geographical location (lat / long - WGS84), and information on texture (% - sand, silt, clay) and soil fertility (chemical variables) associated to gradient of position (edge and interior), and signs of presence-absence (yes or no) of cattle, understory fire and selective logging, (iii) soil_analysis_without gradient – a file with the identification of each sampling unit (forest island), geographical location (lat / long - WGS84), and information on texture (% - sand, silt, clay) and soil fertility (chemical variables) associated to signs of presence-absence (yes or no) of cattle, understory fire and selective logging. The last one represents weighted means (between edge and interior) for each forest island to be used as reference in the ForestPlots.net data. This dataset was supported by the ‘Ecology and Management of Natural Resources of the Roraima Savanna’ project (PPI-INPA 015/122) and the National Council for Scientific and Technological Development of Brazil (CNPq 303081/2011-2), under a fellowship for R.I. Barbosa. M. M. Turcios and M. M. A. Jaramillo were supported by postgraduate fellowships from the Organization of American States (OAS), while L.C.S. Carvalho was supported by a fellowship from Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES/PNPD).