Stable isotope analysis from cushion peatlands as proxies for paleoclimate in the tropical Andes

Authors: Julia Hillin*, Texas A&M University, Julie Loisel, Texas A&M University, Patrick Campbell*, Texas A&M University
Topics: Paleoenvironmental Change, Mountain Environments
Keywords: Distichia miscodes, paleoclimate, oxygen isotope, carbon isotope, isotope-ration mass spectrometry, Peru, peatlands
Session Type: Poster
Day: 4/11/2018
Start / End Time: 8:00 AM / 9:40 AM
Room: Napoleon Foyer/Common St. Corridor, Sheraton, 3rd Floor
Presentation File: No File Uploaded


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 regional data, we obtained surface samples of Distichia muscoides from six sites at various elevations surrounding Mount Ausangate in the Cordillera Vilcanota, 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 us to analyze samples along a broad hydrological gradient. For each sampling site, we analyzed two samples (five vs. ten leaves), which were replicated. For sites with multiple surface samples, we selected ten water table depths 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 region, greatly improving the data for the region.

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