Temperature and microtopography interact to control carbon cycling in a high arctic fen

High arctic wetlands hold large stores of soil carbon (C). The fate of these C stores in a changing climate is uncertain, as rising air temperatures may differentially affect photosynthesis and ecosystem respiration (ER). In this study, open-top warming chambers were used to increase air and soil te...

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Bibliographic Details
Published in:Ecosystems
Main Authors: Sullivan, Patrick F., Arens, Seth J.T., Chimner, Rodney, Welker, Jeffrey M.
Format: Text
Language:unknown
Published: Digital Commons @ Michigan Tech 2008
Subjects:
Climate change
CO 2
Fine root
Greenland
Ingrowth core
Minirhizotron
Peatland
Photosynthesis
Respiration
Wetland
College of Forest Resources and Environmental Science
Forest Sciences
Arctic
Online Access:https://digitalcommons.mtu.edu/michigantech-p/4794
https://doi.org/10.1007/s10021-007-9107-y
Description
Summary:High arctic wetlands hold large stores of soil carbon (C). The fate of these C stores in a changing climate is uncertain, as rising air temperatures may differentially affect photosynthesis and ecosystem respiration (ER). In this study, open-top warming chambers were used to increase air and soil temperatures in contrasting microtopographic positions of a high arctic fen in NW Greenland. CO2 exchange between the ecosystem and the atmosphere was measured on 28 dates over a 3-year period. Measurements of the normalized difference vegetation index, leaf and stem growth, leaf-level gas exchange, leaf nitrogen, leaf δ13C, and fine root production were made to investigate the mechanisms and consequences of observed changes in CO 2 exchange. Gross ecosystem photosynthesis (GEP) increased with chamber warming in hollows, which are characterized by standing water, and in hummocks, which extend above the water table. ER, however, increased only in hummocks, such that net ecosystem exchange (NEE) increased in hollows, but did not change in hummocks with chamber warming. Complementary measurements of plant growth revealed that increases in GEP corresponded with increases in C allocation to aboveground biomass in hummocks and belowground biomass in hollows. Our results and those of several recent studies clearly demonstrate that effects of climate change on the C balance of northern wetlands will depend upon microtopography which, in turn, may be sensitive to climate change.

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