Stable Isotope Analysis From Cushion Peatlands as Proxies for Paleoclimate in the Tropical Andes
Abstract
Peatlands have been utilized as sources for paleoclimate data for many years. Previous studies have established that peatland cores can be used as archives of a region’s climate through analysis of carbon, oxygen, and hydrogen stable isotopes. However, this method has primarily been applied to Sphagnum moss deposits found in high latitudes. To our knowledge, a single study has looked at applying this technique to tropical peatland systems using Distichia muscoides (Juncaceae), the dominant peat-forming species in the Peruvian Andes. The tropical Andes are understudied as a whole in their potential as archives of past climates. In order to improve tropical Andes data, surface samples of Distichia muscoides were obtained from six sites at various elevations surrounding Mount Ausangate in the Cordillera Vilcanota of southeastern Peru. Our hypothesis is that the oxygen isotopic composition of plant tissues will correlate with altitude (proxy for temperature), while the carbon isotopes will be sensitive to local moisture variations. To control for other environmental parameters that might contribute to isotopic fractionation, two sites were intensely sampled, allowing the analysis of samples along a broad hydrological gradient. For each portion of surface material selected, two samples were collected – one of five and one of ten leaves - to be analyzed, and then each of these samples were replicated. For sites with multiple surface samples, ten water table depths were selected at relatively equal intervals and followed the same sampling strategy. Samples are currently being analyzed using isotope-ratio mass spectrometry. Assuming our hypothesis is true, Distichia-dominated peatlands could become important archives for paleoclimate reconstructions across the tropical Andes, greatly improving the data for the region.
Citation
Hillin, Julia Marie (2019). Stable Isotope Analysis From Cushion Peatlands as Proxies for Paleoclimate in the Tropical Andes. Undergraduate Research Scholars Program. Available electronically from https : / /hdl .handle .net /1969 .1 /196672.