SPRUCE S1 Bog Pretreatment Photosynthesis and Respiration for Black Spruce: 2010-2013

This data set contains biochemical, morphological, and physiological data collected between 2010 and 2013 on mature black spruce (Picea mariana) trees at the S1 bog site in northern Minnesota, located 40 km north of Grand Rapids in the USDA Forest Service Marcell Experimental Forest (MEF). These data were collected prior to the initiating of heating and elevation of CO2 for the SPRUCE experiment to assess the response of northern peatland ecosystems to increases in temperature and exposures to elevated atmospheric CO2 concentrations. Seasonal patterns of the photosynthetic capacity of current- (Y0) and one-year old (Y1) foliage were measured in April, May, July, September, August and October between 2010 and 2013. The potential influences of canopy position and needle age on photosynthesis were measured for three successive needle cohorts (Y0, Y1 and two-year old (Y2)) from top, middle and bottom branches in July 2011. Photosynthetic response (A/Ci) curves were produced using portable infrared gas analyzer systems (LI6400XT, Li-COR, USA). A/Ci curves were generated at saturating light levels (PAR > 1000 μmol m-2 s-1) by sequential adjustment of the reference CO2 concentration between 50 and 1600 ppm to assess A across a broad range of intercellular CO2 concentrations. Temperature response surfaces were generated by replication of the A/Ci curves at multiple temperatures.