Impacts of seasonal and permafrost thaw on Picea mariana root function in a subarctic boreal peatland
J. Baltzer, R. Patankar, A. Downey, W. Quinton
Ground perennially at or below freezing for two or more consecutive years.
Boreal forests on discontinuous permafrost:
Permafrost drives forest distribution:
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…
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:
– 6 Edge + 6 Interior plateau trees
– ICT HRM Sap Flow Sensors
– 3 Vertical Positions (root, base, sub-crown)
– June 1 – August 5, 2013
Subcrown sapflow response to thawing edge conditions:
Increased function of plateau-side roots?
Does active layer thickening through the season improve root function?
• Shallow active layer
• Cold soils
Maximum ALT occurs late in July.
Potential increase in root function through growing season?
Root responses to active layer conditions
Picea function in a warming climate:
• Sap flow is reduced in Picea in response to:
– Active layer thaw
– Lateral permafrost thaw