Date Approved

4-2-2016

Graduate Degree Type

Thesis

Degree Name

Biology (M.S.)

Degree Program

Biology

First Advisor

Robert Hollister

Second Advisor

Jim Dunn

Third Advisor

Gary Greer

Abstract

Climate change is impacting terrestrial ecosystems world-wide and the Arctic is particularly vulnerable as it is warming faster and with greater magnitude than other regions. Understanding the responses of arctic plants species to abiotic factors is crucial to predicting the impact climate change will have on the Arctic because plants play critical roles in carbon exchange, energy balance, and trophic interactions. Using data from long-term research sites in Barrow and Atqasuk, Alaska, the purpose of this thesis was to investigate how arctic plants respond to 17-19 years of experimental warming, establish the relative strengths of various abiotic factors in predicting the response of plant traits over time, and examine evidence that climate change will significantly affect plants as the region continues to warm. Plants typically responded to longterm experimental warming with increased inflorescence heights, increased leaf lengths, and accelerated reproductive phenologies, while reproductive efforts responded less consistently. Further analysis revealed that responses to experimental warming tended to dampen during warmer years. Though mostly non-significant, several abiotic factors showed trends over time consistent with regional warming patterns observed in the Barrow area including increasing air and soil temperatures, earlier snowmelts, delayed freeze-ups, drier soils, and increasing thaw depths. Several plant species showed significant trends toward increasing inflorescence heights and reproductive efforts over the same time period. Of the abiotic factors examined, air and soil temperatures yielded the greatest predictive capabilities as these factors were consistently correlated with the greatest number of traits across sites. Unlike other traits, the reproductive efforts of many species were best predicted using temperatures during the year prior to flower burst. When we compared experimental warming responses with trends in abiotic factors and traits over time we found strong evidence that climate change will likely cause significant shifts 5 in the growth and reproductive efforts of at least seven plant species at these sites. This study illustrates the value of long-term monitoring coupled with experimentation and lays the groundwork for future studies examining the ecosystem consequences of climate change on the Barrow region.

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