17,000years of vegetation, fire and climate change in the eastern foothills of the Andes (lat. 44°S)


Virginia Iglesias, Vera Markgraf, Cathy Whitlock


Palaeogeography, Palaeoclimatology, Palaeoecology


Paleoenvironmental records from Patagonia reveal the importance of latitude, longitude and elevation in shaping the response of vegetation to climate change. We examined the vegetation, fire and watershed history from two sites at lat. 44°S, as inferred from pollen, charcoal and lithologic data. These reconstructions were compared with independent paleoenvironmental records to better understand ecosystem dynamics along the southeastern Andes (lat. 41–50°S). Our results show that at lat. 44°S, late-glacial heath-steppe was colonized by trees at ~ 14,200 cal yr BP and forests became more closed at 11,500 cal yr BP. Differences in forest cover between the two sites were likely due to elevation-dependent disparities in humidity and fire. North of lat. 44°S, increasing precipitation favored initial forest development at 16,500 cal yr BP, while dry conditions restricted tree expansion in the south until 7000 cal yr BP. The time-transgressive pattern is attributed to a gradual southward shift in the Southern Westerlies resulting from deglaciation and increasing annual insoltion. Present-day vegetation developed at all latitudes during the middle to late Holocene, when the core of the Southern Westerlies reached its modern position (50°S). Asynchronous forest expansions north and south of lat. 45°S between 5000 and 3000 cal yr BP are ascribed to centennial cycles of contraction and expansion of the Southern Westerlies, which led to seasonal variations in precipitation at the core and northern border of the wind belt. Synchronous oscillations in tree abundance along the eastern Andes prevailed during the last 3000 years. Decreased forest cover at all latitudes between 2500 and 1500 cal yr BP is concurrent with La Nina-like conditions and high solar irradiance. These climate drivers likely decreased effective moisture and favored fires at all latitudes.



How is this information collected?

This collection of Montana State authored publications is collected by the Library to highlight the achievements of Montana State researchers and more fully understand the research output of the University. They use a number of resources to pull together as complete a list as possible and understand that there may be publications that are missed. If you note the omission of a current publication or want to know more about the collection and display of this information email Leila Sterman.