| dc.description.abstract | Paleoclimate reconstructions allow us to build a better picture of how climate has changed over time. However, relatively little research has been done in the higher latitudes of the southern hemisphere, leaving a gap in our knowledge. Changes in temperature and moisture can have significant impacts on local vegetation growth structure and ecosystem functioning; these changes in hydroclimatic conditions can be traced using stable isotope analysis of carbon (δ13C), oxygen (δ18O), and hydrogen (δ2H) in peat deposits. Throughout this project, I aimed to determine the effects of changes in precipitation amounts and sources of moisture in southernmost Patagonia using peat-core samples collected in 2010. The top 350 cm (~ 4200 cal. BP) of the core was analyzed in 2-centimeter increments. For each horizon, Sphagnum magellanicum moss stems were handpicked and cleaned. Cellulose from the moss stems was then extracted following the alkaline bleaching method and the samples were analyzed for δ13C and δ18O using a mass spectrometer. The combination of these isotopes allows to tease apart local (soil moisture) vs. regional (moisture source) environmental effects. On the basis of previous studies, cellulose values that are more depleted in the heavier isotope are expected to correspond to wetter conditions (and less depleted values with drier conditions). Our results show a progressive wetting of the peatland from 4000 years ago until approximately 1500 years ago; conversely, the past 1000 years have seen drying conditions. These results coincide with other regional paleoclimate reconstructions that suggest decreased winds during the earlier period (which can be interpreted as wetter conditions, likely due to lower evaporation), and vice versa during the more recent period. | |
