Document Type

Thesis

Degree

Master of Science (MS)

Major/Program

Biology

First Advisor's Name

Steven F. Oberbauer

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

William T. Anderson

Third Advisor's Name

Jennifer H. Richards

Keywords

ecosystem respiration, carbon dioxide, water uptake, deuterium, stable isotope, Arctic, Alaska, tundra, cold season, low temperature, physiology

Date of Defense

10-30-2012

Abstract

The cold season in the Arctic extends over eight to nine months during which ecosystem gas exchange and water balance of arctic plants have been largely unexplored. The overall objective of this thesis was to examine two critical gaps in our knowledge about tundra cold season processes – ecosystem respiration at very low temperatures and water uptake during the winter-spring transition. I determined the temperature response of ecosystem respiration of tundra monoliths down to temperatures as low as can be expected under snow-covered conditions (-15 °C). Temperature responses fit the Arrhenius function well with Q10 values over the range of -15 to 15 °C varying from 6.1 to 4.8. I used deuterium-enriched water (2H2O) as a tracer to evaluate water uptake of evergreen plants at snowmelt when soils are largely frozen. The results revealed that evergreen plants take up water under snow cover, possibly via roots but undoubtedly by foliar uptake.

Identifier

FI12113001

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