TY - JOUR
T1 - Growth of Eastern Cottonwoods (Populus deltoides) in elevated [CO2] stimulates stand-level respiration and rhizodeposition of carbohydrates, accelerates soil nutrient depletion, yet stimulates above- and belowground biomass production
AU - Barron-Gafford, Greg
AU - Martens, Dean
AU - Grieve, Katie
AU - Biel, Karl
AU - Kudeyarov, Valery
AU - McLain, Jean E.T.
AU - Lipson, David
AU - Murthy, Ramesh
PY - 2005/8
Y1 - 2005/8
N2 - We took advantage of the distinctive system-level measurement capabilities of the Biosphere 2 Laboratory (B2L) to examine the effects of prolonged exposure to elevated [CO2] on carbon flux dynamics, above- and belowground biomass changes, and soil carbon and nutrient capital in plantation forest stands over 4 years. Annually coppiced stands of eastern cottonwoods (Populus deltoides) were grown under ambient (400 ppm) and two levels of elevated (800 and 1200 ppm) atmospheric [CO2] in carbon and N-replete soils of the Intensive Forestry Mesocosm in the B2L. The large semiclosed space of B2L uniquely enabled precise CO2 exchange measurements at the near ecosystem scale. Highly controllable climatic conditions within B2L also allowed for reproducible examination of CO2 exchange under different scales in space and time. Elevated [CO2] significantly stimulated whole-system maximum net CO2 influx by an average of 21% and 83% in years 3 and 4 of the experiment. Over the 4-year experiment, cumulative belowground, foliar, and total aboveground biomass increased in both elevated [CO2] treatments. After 2 years of growth at elevated [CO2], early season stand respiration was decoupled from CO2 influx aboveground, presumably because of accelerated fine root production from stored carbohydrates in the coppiced system prior to canopy development and to the increased soil carbohydrate status under elevated [CO2] treatments. Soil respiration was stimulated by elevated [CO2] whether measured at the system level in the undisturbed soil block, by soil collars in situ, or by substrate-induced respiration in vitro. Elevated [CO2] accelerated depletion of soil nutrients, phosphorus, calcium and potassium, after 3 years of growth, litter removal, and coppicing, especially in the upper soil profile, although total N showed no change. Enhancement of above- and belowground biomass production by elevated [CO2] accelerated carbon cycling through the coppiced system and did not sequester additional carbon in the soil.
AB - We took advantage of the distinctive system-level measurement capabilities of the Biosphere 2 Laboratory (B2L) to examine the effects of prolonged exposure to elevated [CO2] on carbon flux dynamics, above- and belowground biomass changes, and soil carbon and nutrient capital in plantation forest stands over 4 years. Annually coppiced stands of eastern cottonwoods (Populus deltoides) were grown under ambient (400 ppm) and two levels of elevated (800 and 1200 ppm) atmospheric [CO2] in carbon and N-replete soils of the Intensive Forestry Mesocosm in the B2L. The large semiclosed space of B2L uniquely enabled precise CO2 exchange measurements at the near ecosystem scale. Highly controllable climatic conditions within B2L also allowed for reproducible examination of CO2 exchange under different scales in space and time. Elevated [CO2] significantly stimulated whole-system maximum net CO2 influx by an average of 21% and 83% in years 3 and 4 of the experiment. Over the 4-year experiment, cumulative belowground, foliar, and total aboveground biomass increased in both elevated [CO2] treatments. After 2 years of growth at elevated [CO2], early season stand respiration was decoupled from CO2 influx aboveground, presumably because of accelerated fine root production from stored carbohydrates in the coppiced system prior to canopy development and to the increased soil carbohydrate status under elevated [CO2] treatments. Soil respiration was stimulated by elevated [CO2] whether measured at the system level in the undisturbed soil block, by soil collars in situ, or by substrate-induced respiration in vitro. Elevated [CO2] accelerated depletion of soil nutrients, phosphorus, calcium and potassium, after 3 years of growth, litter removal, and coppicing, especially in the upper soil profile, although total N showed no change. Enhancement of above- and belowground biomass production by elevated [CO2] accelerated carbon cycling through the coppiced system and did not sequester additional carbon in the soil.
KW - Poplars
KW - Soil carbohydrates
KW - Soil nutrient depletion
KW - Stand-level CO exchange
UR - http://www.scopus.com/inward/record.url?scp=19344365500&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=19344365500&partnerID=8YFLogxK
U2 - 10.1111/j.1365-2486.2005.00985.x
DO - 10.1111/j.1365-2486.2005.00985.x
M3 - Article
AN - SCOPUS:19344365500
SN - 1354-1013
VL - 11
SP - 1220
EP - 1233
JO - Global change biology
JF - Global change biology
IS - 8
ER -