2009. Patterns of total ecosystem carbon storage with changes in soil temperature in boreal black spruce forests. Ecosystems

• Main Authors: E. S. Kane, J. G. Vogel
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: permafrost; Alaska
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.373.2370; http://www.lter.uaf.edu/dev2009/pdf/1274_Kane_Vogel_2009.pdf

To understand how carbon (C) pools in boreal ecosystems may change with warming, we measured above- and belowground C pools and C increment along a soil temperature gradient across 16 mature upland black spruce (Picea mariana Mill. [BÆS.P]) forests in interior Alaska. Total spruce C stocks (stand and root C) increased from 1.3 to 8.5 kg C m-2 with increasing soil summed degreedays (SDD> 0°C at 10 cm) across sites, whereas soil C stocks decreased from 11.9 to 6.3 kg C m-2 with increasing SDD. Spruce C and organic soil C, which combined represent maximum C accrual since the last fire, increased with soil heat sums until 600 SDD, and then plateaued with increasing SDD across sites (R 2 = 0.61, P = 0.002; second-order polynomial regression). The sum of soil and total spruce C (total ecosystem C, TEC) reached its maximum in the middle-range of soil temperatures measured (approximately 600 SDD), and was lower in the coolest (139 SDD) and the warmest (914 SDD) forests. The opposing trends between above- and belowground pools resulted in C shifting from the soil to spruce biomass with warmer soil temperatures. A shift in C distribution from below- to aboveground pools, as temperature increases, has implications for the vulnerability of C lost in boreal forest wildfires. The strongly negative relationship between surface mineral soil C stocks and increasing temperatures warrants further research into the potential loss of deep mineral soil C stocks with continued warming, especially in forests presently underlain with permafrost. Key words: organic soil; carbon storage; biomass; climate change; fire; productivity; decomposition; permafrost; black spruce.