Doctoral Dissertation Research: Reconstructing How Ecosystems Develop in High Northern Latitudes Using Genetic Markers and Temperature Signals in Lake Sediments

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

This doctoral dissertation research project will reconstruct the plant community of a lake catchment over the last 7,000 years in order to better understand how tundra ecosystems respond to changing environmental conditions. As the Arctic warms and vegetation ranges are expected to expand northward; the increase in woody vegetation at high latitudes has important implications for both global and northern latitude ecosystems. By identifying how past plant community shifted and by reconstructing temperatures using two new techniques that analyze lake sediments, the doctoral student will enhance understanding about the complexities of the interplay between climate and biogeography at high latitudes both in the past and in a potentially warmer future. The project will provide research education and training opportunities for undergraduate students. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising doctoral student to establish a strong independent research career. The doctoral student will use a combination of relatively new techniques to analyze past environments. One is the analysis of previously dated lake sediments for sedimentary ancient DNA, the complex mixture of degraded DNA found within bulk sediment, in order to identify the plants that lived within the lake catchment during the Holocene Epoch. The second technique the student will employ is a recently developed biochemical tool, the use of a distribution of a class of bacterial cell membrane lipids called "branched glycerol dialkyl glycerol tetraethers" (brGDGTs) which is able to estimate past temperature. Using these techniques, the student will seek answers to the following sets of research questions: 1) Following the retreat of glaciers, how long did it take for dwarf shrubs to become established in the lake catchment? 2) How did plant diversity respond to the warmth of the early Holocene and cooling during the Late Holocene? 3) When did Betula (dwarf birch), a shrub that likes warmer temperatures currently near its northern limit in this field area, become established, and did it remain present through Holocene temperature fluctuations? Through the use of these new techniques in combination, the project's results will offer new perspectives about the climatic and temporal factors influencing northward plant migration in high northern latitudes.