The Spruce-Peatland Responses Under Climatic and Environmental Change (SPRUCE) experiment is being conducted to identify environmental response functions for organisms and ecosystems to rapidly changing climate conditions. A multi-plot facility for both above and deep belowground warming of a tall statured peatland vegetation (Picea - Larix trees) was completed and brought to full operational status in August 2015. These in situ warming facilities combine air warming with active deep peat heating in a conceptually simple concept designed for a decade of continuous operation. Both air warming applied within a 911 m3 open top enclosure (12 m diameter), and deep peat heating at -2 m is maintained at the following target warming treatments: +0, +2.25, +4.5, +6.75 and +9 °C with respect to the fully constructed control enclosures. Two designated ambient plots are also monitored. Routine monitoring of thermistors is done for air at +0.5, +1, +2 and +4 m, and for hummock and peat temperatures at +0.2, +0.1, 0, -0.05, -0.1, -0.2, -0.3, -0.4, -0.5, -1 and -2 m. The zero reference height is the peat surface within local hollows. All air and warming treatments are being run continuously throughout all seasons.
Results/Conclusions
Belowground warming, initiated June 2014, required as much as two months to achieve target differential temperatures, but has been maintained within ± 0.5 °C of targets with essentially no down time due to the self insulating nature of the peat soils. Air warming, initiated in mid-August 2015, has been similarly maintained within ± 0.3 °C of targets with diurnal and seasonal cycles. A four fold redundancy built into the air heating system for each warming enclosure allows for periodic maintenance and maintenance of most temperature differentials. Down time for power outages has been very limited. Diurnal and seasonal temperature patterns are conserved in all warming treatments for both above and belowground differentials. Total monthly energy requirements to maintain air warming, soil warming and air handling blowers varies a bit from warm to cold seasons as follows: 64,283 to 80,102 J per months for air warming, 954 to 1782 J per month for deep peat heating, and 7,999 to 8,194 J per month for air handling. The enclosed nature of the aboveground air volume underscores the need to characterize environmental variations from ambient conditions. The poster will enumerate the nature of variation for enclosure relative humidity, radiation, dew and snow accumulation, and wind velocity.