Pollen Deposition on a Tropical Andean Ice Cap: Testing a New Automated Tauber Trap

University Of Southern Mississippi, Hattiesburg MS

Investigators

Abstract

Paleoenvironmental records recovered from the tropics are extremely important, especially when the current warming trends in mean global temperature are considered. To date, tropical ice cores remain one of the best sources for both long-term and high-resolution paleoenvironmental data. Pollen studies of these ice cores, though few, have shown these records to be sensitive indicators of vegetation change on a variety of time scales. Understanding this process and the affect it has on the pollen assemblage found within the ice cap is essential to the accurate interpretation of the fossil pollen record. Furthering the use of pollen in ice core research is critically important, as direct biological evidence is the only way to accurately reconstruct biological parameters, such as paleovegetation, within an ice core. Because pollen is the only biological proxy (besides bacteria) consistently found in ice cores, better methods must be developed for interpreting these data more accurately. To study the depositional processes of pollen on high-alpine ice caps, modern pollen must be collected in traps above the ice cap and compared to the pollen that is actually incorporated into the ice. Current technology severely hampers capabilities to do this, however, as traditional pollen traps must be monitored regularly, which is impossible in harsh high-alpine environments. This research project aims to further the accuracy and reliability of tropical ice-core pollen records by researching the depositional processes of pollen on a high-alpine, tropical ice cap on Mount Sajama in western Bolivia. The investigators will thoroughly test a new, automated pollen trap that has the potential to lift the current limitations on pollen trapping and permit reliable, modern pollen studies in remote locations. These pollen traps, along with a snow accumulation sensor will be mounted to an instrument tower at the summit of Mount Sajama. Each trap will be programmed to collect pollen for a certain period of time during a year. At the end of each year, the pollen in each trap will be analyzed and compared against each other and with samples recovered from a snow pit at the summit. The accumulation sensor will provide time-control within the pit so that trap samples can be compared to their equivalent time period within the pit. The results of this study will provide the first data on pollen deposition from a tropical ice cap. These data will help to define the seasonality of Andean ice core pollen and determine what species or pollen types are being preferentially filtered or overrepresented by the process of deposition. The equipment developed in this proposal will allow for expansion of this kind of research to other ice caps around the globe. Additional studies will lead to a full understanding of this process, making the paleovegetational reconstructions from ice cores more accurate and reliable. The ultimate goal of this project is to establish pollen as such a reliable proxy that it is routinely analyzed in all ice-core research. In addition to this, the automated pollen trap tested in this proposal will have a wide range of uses that will benefit the worldwide palynological community by allowing high-resolution pollen collection in remote environments.