Paleoenvironmental trends in Venezuela during the last glacial cycle

This chapter summarizes and updates the main Quaternary paleoclimatic and sea-level trends recorded in Venezuela, and provides a paleoenvironmental framework for studies addressing biogeographical, ecological, and evolutionary topics. Venezuela has a number of localities that have provided paleoenvironmental sequences in the neotropical, circum-Caribbean domain, such as the Cariaco basin, Lake Valencia, the Mérida Andes, and the Guayana region (e.g., Markgraf 2001). Venezuela encompasses a wide range of physiographic, climatic, and biogeographic conditions because of its geographic location. This spatial heterogeneity has led to complex, but interesting, paleoenvironmental reconstructions. Previous paleoenvironmental reviews (Rull 1996, 1999a) identified several thematic areas that needed further attention: modern analog studies with numerical calibrations, consistent evidence for the period before the Last Glacial Maximum (LGM), high-resolution records for the last millennium, and coordinated multiproxy studies. This review is focused on recent advances in these topics carried out during the last decade. This is not an exhaustive review, containing all the published paleoenvironmental studies, but is an attempt to identify the significant, welldocumented climate/environment events and trends. The time frame considered is from the last glacial cycle, ca. 70,000 years onward, which is the period with more reliable, well-dated paleoclimatic evidence. Paleoenvironmental interpretations from poorly dated records are not considered here. Whenever possible, ages are presented as calibrated (or calendar) years or kiloyears before present (cal yr BP or ka BP); otherwise, radiocarbon years or kiloyears before present (14C yr or ka BP) are used. The review begins with a section on present-day environmental conditions, with emphasis on the relationship between climate and vegetation, a necessary aspect for paleoenvironmental reconstruction. This review is far from exhaustive, but provides the information necessary to understand the sections that follow. The second section is an account of the available paleoenvironmental evidence discussed by region. This basic information has been written by researchers currently working on the paleoecology and paleoclimatology of each area. The final section summarizes and organizes the information in a chronological perspective, from the last glaciation to the present, to identify events that are well established, as well as those that need additional research. © 2010 by Indiana University Press. All rights reserved.