Using diatoms preserved in peat deposits to track environmental changes in the Cordillera Vilcanota, Peru

Abstract

Recent climate change in alpine regions is outpacing many other parts of the world, threatening to degrade specialized ecosystems and their associated ecological services. Long-term data are sparse, especially in remote regions such as the Cordillera Vilcanota in Peru. Diatoms preserved in peat deposits (known locally as bofedales) have the potential to provide a long-term context for environmental changes resulting from recent climate change. This thesis examined diatom assemblages and other siliceous indicators preserved in a 90 cm peat core to reveal long-term environmental changes spanning the past several centuries. The diatom assemblages indicate that cool, oligotrophic conditions occurred contemporaneously with peat initiation at the end of the Little Ice Age, and that these conditions persisted until the late 20th century, at which point drier conditions became prevalent. Recently, the diatoms indicate a shift to wetter and more acidic conditions that are characteristic of a poor fen. These changes may reflect glacial retreat due to climate change or ENSO events, the latter of which is known to modulate precipitation in the western tropical Andes. This research also tracked peat accumulation rates that are amongst the highest in the world, highlighting the important role these environments play in carbon sequestration. Although there have been few paleoenvironmental studies in this region, these data generally match interpretations made from other archives such as ice cores and high alpine lake sediments. This thesis is the first to provide the environmental history of a bofedal in the Cordillera Vilcanota using diatoms and demonstrates the potential for future research in this region using siliceous bioindicators preserved in peat deposits.