Lagoa da Pata revisitada: maior sazonalidade como causa do reagrupamento da comunidade vegetal durante o último período glacial na Amazônia

Abstract

Pollen in sediments of Lake Pata, northwestern Amazon, was studied with the aim of covering the entire last glacial cycle. Although a tall tropical forest seems to have remained unbroken throughout the past ~120,000 years, reanalyses and reinterpretation of data suggest the so-called nonanalog ice age vegetation was more seasonal, resembling present day seasonal tropical dry forests. This agrees with a prolonged annual dry season and polar air advection as the features setting the region biome. The very local paleoenvironmental interpretation cannot be perfectly extended to a broader lowland region because like presently, orographic rain caused the hill to have remained moister and less susceptible to drought, unlike the overall mesic lowland forests of the upper Rio Negro basin. Thus the dry events affected the region more drastically than what could have been assessed by means of a pollen study at the hill. Seasonally dry and moderately cooler is the most probable climatic picture for the region during the last ice age