Attalea princeps is an important palm species that shapes the forest-savanna mosaic in Beni, Bolivia, because it dominates and shapes the two principal forest landscape elements (forest islands and gallery forest), and it provides a vital microhabitat, food and nesting source for numerous plant and animal species. The forest-savanna mosaic is used for extensive grazing, and the palm population is declining on the forest islands due to a low regeneration rate, which threatens the maintenance of this landscape. We therefore examined the (a)biotic factors that influence the population structure of Attalea in the centers and edges of forest islands and gallery forests. Ninety-one 0.1 ha plots were established and 500 palm adults and 3700 juveniles were measured for their size, health condition and fire damage. For each plot habitat characteristics, such as landscape position, grazing pressure, and soil conditions were measured. Attalea population density was significantly lower on the forest islands than in the gallery forests, especially in the juvenile life stage. A structural equation model showed that juvenile density is positively related to the health condition of the juveniles and amount of fruits present, where the amount of fruits is positively affected by the condition of the adults. Juvenile density is negatively influenced by grazing, affecting the health condition of the juvenile, as well as organic matter and phosphate availability in the soil. Therefore, it is recommended to decrease the grazing pressure by decreasing livestock densities, fencing off vulnerable forest islands, or by rotating cattle.

Palm and soil measurements, Beni savannaThis dataset contains plot level data collected in the Barba Azul Nature Reserve, Beni Savanna, Bolivia between July and October 2016 as part of the MSc thesis project of Iris Hordijk, Fabian Meijer and Esther Nissen. Data on palm abundance and condition, juvenile abundance and condition, fruit density, soil fertility, general plot characteristics and geographic information are measured and recorded. The dataset is owned by the data collectors, Wageningen University and the Bolivian NGO Armonía.2016-PlotLevelDataPalmsSoilAndGeneralCharacteristics.csv