Eight Mile Lake Research Watershed, Carbon in Permafrost Experimental Heating and Drying Research (CiPEHR and DryPEHR): Weekly 13C Keeling Plot Signatures of Ecosystem Respiration from CiPEHR, DryPEHR and vegetation removal plots, and auxilliary data, 2015

The Carbon in Permafrost Experimental Heating Research (CiPEHR) project addresses the following questions: 1) Does ecosystem warming cause a net release of C from the ecosystem to the atmosphere?, 2) Does the decomposition of old C, that comprises the bulk of the soil C pool, influence ecosystem C loss?, and 3) How do winter and summer warming alone, and in combination, affect ecosystem C exchange? We are answering these questions using a combination of field and laboratory experiments to measure ecosystem carbon balance and radiocarbon isotope ratios at a warming experiment located in an upland tundra field site near Healy, Alaska in the foothills of the Alaska Range. How does warming and water table change impact the phenology of dominant plant species? We are answering these questions using a combined warming and drying experiment (DryPEHR), which is situated with the Carbon in Permafrost Experimental Heating Research (CiPEHR) project and located in an upland tundra field site near Healy, Alaska in the foothills of the Alaska Range. Warming treatment here refers to growing season air temperature warming (~1C) using open top chambers (OTC) combined with soil 'warming' using snow fences during the snow covered months. Drying is achieved using an automated pumping system that lowers the water table in the dry plots. Soil warming and OTC air warming on CIPEHR plots began in 2008; OTCs and drying on DryPEHR in 2011, though the soil warming effect had legacy since 2008. Vegetation removal was done outside the CiPEHR footprint, in July 2012. All vegetation was clipped at the surface and plots were trenched to 30cm, regrowth was prevented by frequent weeding and by 2015 very little new growth was observed in the plots. Vegetation removal plots were paired with undisturbed, vegetated plots. The data presented here specifically addresses the questions, 1) What is the seasonal signal of ecosystem respiration 13C during the growing season, from snow melt to snow fall, 2) How does permafrost degradation (though soil warming) and moisture trajectory affect the sources of ecosystem respiration, and 3) What is the signal of ecosystem respiration in the absence of vegetation, and how does the signal change seasonally? This data set contains calculated Keeling Plot Reco estimates of 13C used for publication, accompanying environmental and biological data, and R code to calculate Keeling Plot intercepts from high-frequency raw 13C and CO2 data.