Holocene climate variability and the effect of anthropogenic activities on the vegetation landscape of western-central Mexico

Abstract

Atmospheric forcings control climate variability and at the same time control vegetation distribution and forest fires during the Holocene. Paleoenvironmental studies are scarce in western Mexico, particularly those documenting vegetation change, landscape dynamics, and fire regimes. This study presents a vegetation and fire occurrence reconstruction in the Etzatlán-Magdalena paleolake, western Mexico, during the Holocene. The reconstruction relies on fossil pollen, macrocharcoal and microcharcoal analyses of a clay sediment core. In the early Holocene (10–5.8 ka), climatic conditions were humid between 10 and 9 ka, represented by cloud forest of Liquidambar, Juglans, and Betulaceae. After 9 ka Quercus forest expanded and a trend towards warm conditions was detected, associated with high fire activity, suggesting the presence of a dry forest. Fire episodes at local and regional scale had a long-term negative effect on temperate and cloud forests. In the middle Holocene (5.8–2.1 ka), temperate forest was replaced by dry forest, indicating a drier climate. In the late Holocene (2.1–0.3 ka), the expansion of disturbance taxa and the low local fires indicated an open landscape and dry conditions. Human activity was documented by an increase of Cheno-Amaranthaceae, Poaceae and microcharcoal concentration after 3.5 ka. This research provides relevant information on the vegetation dynamics in a region with a long history of human settlement.