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Impacts of seasonal and permafrost thaw on Picea mariana root function in a subarctic boreal peatland

Impacts of seasonal and permafrost thaw on Picea mariana root function in a subarctic boreal peatland
J. Baltzer, R. Patankar, A. Downey, W. Quinton

Permafrost:
Ground perennially at or below freezing for two or more consecutive years.

Sap Flow Workshop 2013 1

Boreal forests on discontinuous permafrost:

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Permafrost drives forest distribution:

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Climate warming and the boreal

•Boreal productivity and extent limited by temperature
•Model predictions: enhanced growth and productivity, forest expansion
•The situation is more complicated than climate envelope models suggest…

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1) How are trees responding to seasonal active layer thaw?
Prediction: Thickening active layer will improve root function
2) How are trees responding to lateral permafrost thaw?
Prediction: Lateral thaw and ground surface subsidence will induce functional loss of roots

Sap Flow Measurements:

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– 6 Edge + 6 Interior plateau trees
– ICT HRM Sap Flow Sensors
– 3 Vertical Positions (root, base, sub-crown)
– June 1 – August 5, 2013

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Subcrown sapflow response to thawing edge conditions:

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Increased function of plateau-side roots?

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Does active layer thickening through the season improve root function?

Early season
• Shallow active layer
• Cold soils
Maximum ALT occurs late in July.
Potential increase in root function through growing season?

Sap Flow Workshop 2013 12

Root responses to active layer conditions

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Picea function in a warming climate:

• Sap flow is reduced in Picea in response to:
– Active layer thaw
– Lateral permafrost thaw

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Thank you!

Sap Flow Workshop 2013 16

Bill Quinton

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           Rajit Patankar

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       Alec Downey

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