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.本数据集包含2010至2013年间，采集自美国明尼苏达州北部S1泥炭沼泽样地的成熟黑云杉（Picea mariana）植株的生化、形态及生理数据。该样地位于大急流城以北40公里处，隶属于美国农业部（United States Department of Agriculture, USDA）林务局马塞尔实验林（Marcell Experimental Forest, MEF）。这些数据采集于SPRUCE实验启动加热与CO₂富集处理之前，旨在评估北方泥炭地生态系统对温度升高及大气CO₂浓度升高暴露的响应。2010至2013年间的4月、5月、7月、9月、8月和10月，研究人员测定了当年生（Y0）和一年生（Y1）针叶的光合能力季节变化模式。2011年7月，研究人员针对顶部、中部和底部枝条的三个连续针叶龄组（Y0、Y1及两年生（Y2）），测定了冠层位置与针叶龄对光合作用的潜在影响。光合响应（A/Ci）曲线采用便携式红外气体分析仪系统（LI6400XT，Li-COR，美国）构建：通过依次将参比CO₂浓度调整至50至1600 ppm区间，在饱和光强（光合有效辐射PAR > 1000 μmol·m⁻²·s⁻¹）条件下生成该曲线，以评估跨大范围胞间CO₂浓度下的光合速率A。温度响应曲面通过在多个温度下重复测定A/Ci曲线构建得到。