Glacial and Postglacial Pollen Records from the Ecuadorian Andes and Amazon

Abstract

A long pollen record is derived from sediments of a lake dammed behind a low moraine of the last glaciation at 3°S latitude in the Ecuadorian Andes and is compared with a glacial age pollen record from the Amazon rainforest immediately below. Lake Surucucho (Llaviucu) lies at 3180 m on the Amazonian flank of the Andes and above the glacial age pollen record from San Juan Bosco at 970 m. The Surucucho pollen record is interpreted as showing treeless vegetation in glacial times, advance of treeline in late-glacial time, and Holocene development of modern Andean forests. Combining the Surucucho and San Juan Bosco records shows that Andean vegetation was affected by glacial cooling at all elevations. Vegetation did not move up and down slope as belts. Rather, plant associations were reformed as temperature-sensitive species found different centers of distribution with changing temperature.