The PELD FORR site is compound by five locations represented by two protected areas (Viruá National Park, hereafter, PNV, and Maracá Ecological Station, hereafter EEM), which are part of the Program for Research in Biodiversity (PPBio / MCTI), and three private forest areas. The selected protected areas are important for the conservation of several tree species (such as Centrolobium paraense), medium and large mammals, and several species of birds of conservation concern. Each of the protected areas selected as our study sites has a network of 30 permanent plots of 1 hectare, which are systematically distributed over an area of ~25 km2, and where ~20,000 trees are marked, mapped, and being monitored at intervals of five years since 2006. The forest areas outside protected areas surround PNV and are Brazil nut stands (Berthollethia excelsa) where rural population collect nuts for own consume or to sell. Working with the surrounding community is vital in proposing alternatives that combine economic return with forest conservation and the diffusion of sustainable agricultural practices is very important to hold the advance of deforestation and the threat of fire within the park boundaries. Being located at the northern edge of the Amazon, the PELD FORR site presents climatic and geological characteristics unique in the Amazonian scenario. Rainfall patterns, for example, are very different from other Amazonian active LTER sites, with a much longer dry season and a precipitation gradient that ranges between 1700-2300 mm/year. In addition, the selected areas represent forest ecosystems that are rare elsewehere in the Amazon and represent two important ecotones (white-sand / humid forest, and savanna / seasonal forest), which are sensitive to droughts, which should become increasingly frequent in the Amazon in predicted future climate scenarios. Extreme climatic events, like El Niño have affected Roraiman forest dramatically in previous years (e.g, 1997-98, 2010 and 2015-16), resulting in wild fires of great proportions.
The Viruá National Park (PNV) has a total area of 214,950.52 hectares and was created in 1998 to protect samples of the ecosystems of the south-central region of Roraima, where the Campinaranas predominate, a term that designates a phytophysiognomy that occurs in areas of sandy and often hydromorphic soils. In the regional context, the Park is part of the Campinaranas Ecological Region, which extends through the Negro, Branco and Orinoco river basins, covering areas of the Brazilian, Colombian and Venezuelan Amazon. Recently the park received the title of a Ramsar site, showing its importance as a wetland area. PNV is marked by high environmental heterogeneity, with a great variety of physiognomies associated to topography, hydrology and soils. The predominant vegetation is the ecotone campinarana (white-sand forest) with extensive alluvial forest areas (floodplain and igapó forests) and mainland forest enclaves that include Open Lowland Ombrophilous Forests, as well as small enclaves of Open Ombrophylous Submontane Forests on isolated residual hills. PNV presents high floristic diversity, with 1262 registered plant species, including 1149 angiosperms and 110 pteridophytes (ICMBio, 2014). The soil types that predominate in the PNV are sandy, nutrient poor, poorly drained and developed over extensive sedimentary plains (Hydromorphic Quartzic Neosols and Hydromorphic Humic Spodosols). The low altitude of the land (between 45 and 60m) causes periodic flooding due to elevation of the water table or the accumulation of rainwater, whose flow is hampered by the presence in depth of layers cemented by iron oxides, aluminum oxides and organic matter (Mendonça et al., 2014). The low water storage capacity of these soils causes extreme water deficits during dry seasson. Parna Viruá is in a climatic transition zone (Aw-Am by the Köppen classification system) with the dry period peak between January-March and the rainy season between May-August (Schaefer et al., 2008).
The Maracá Ecological Station (EEM) is a river island, about 830 km2 (60 km long x 25 km wide), located on the river Uraricoera, one of the main tributaries of Rio Branco, the main river of Roraima. Most of the island (90%) is covered by forests, although in the southern and eastern portions savannah patches are found. The forest phytophysiognomies present on the island include Ombrophilous Forest and Seasonal Forest. The height of the canopy varies from 25 to 40m, with occasional emergent trees reaching 50m in height. The diversity of tree species is low, compared to other areas of the Amazon (~ 80 species with dap ≥10 cm in 1.5 hectares), with occurrences of monodominant forest patches of Peltogyne gracilipes (Milliken & Ratter, 1998). Esec Maracá is home to populations of endangered tree species such as Albizia glabripetala (CNCFlora, 2016a) and Centrolobium paraense (CNCFlora, 2016b). Podzolic soils, mostly dystrophic and containing low base saturation, predominate on the island (Nortclif & Robison, 1991). In areas where the soil has low depth of root penetration, temporary flooding on the surface, and a high Mg: Ca ratio, monodominant forest patches are observed. Esec Maracá is located in the area described for the "Aw" climate (tropical climate with dry winter season). In the period from 1986 to 2004, the average annual rainfall registered was 2091 mm (ICMBio / RR). In general, the wettest month is July and the driest month, February (Nascimento, 1997). For the same period, from April to September (rainy season), the average rainfall was 1635 mm, and in the months of October to March (dry season), the average was 456 mm.
Brazil nut stands: The permanent plots located in forests with natural occurrence of Brazil nut (Bertholletia excelsa) were established by Embrapa Roraima between 2005 and 2008, with the objective of studying population dynamics (growth, mortality and recruitment) and fruit production and seeds in natural populations of the species. Each plot has a total area of nine hectares (300 x 300 m), subdivided into 144 subplots of 25 x 25 m, in which all Brazil nut trees with DBH (diameter at 1,30 m from the soil) equal to or greater than 10 cm were marked, mapped and measured (stem and crown diameter and total height). All plots have been monitored annually since its establishment (2005-2008). In total, there are five plots, one of which is in the municipality of São João da Baliza, 313 km from the capital Boa Vista, and four in the municipality of Caracaraí, 135 km from the capital. The plot located in São João da Baliza was installed in 2006 and has 34 marked individuals (average density of 3.8 Brazil nut trees/hectare). The region is characterized by Dense Ombrophylous Forest vegetation and the climate is Awi type (tropical humid with small dry season during the year), with a dry period between November and March (Barbosa, 1997). The plots installed in the municipality of Caracaraí are located around the Viruá National Park. Two plots were installed between 2006 and 2007 in a 400 ha forest fragment where the average density of Brazil nut trees was estimated as 13.2 trees/hectare, totalizing 238 individuals. Other two plots were installed in 2008 in an area with density of 6.3 trees/hectare, totalizing 113 individuals. The vegetation in the region was classified as Open Tropical Rainforest with Palms and the climate of the region as Ami (rainy tropical, with small dry season), with average annual precipitation between 1700-2000 mm, being the rainy period between April and August.
