Re-assessment of plant carbon dynamics at the Duke free-air CO(2) enrichment site: interactions of atmospheric [CO(2)] with nitrogen and water availability over stand development.
*The potential for elevated [CO(2)]-induced changes to plant carbon (C) storage, through modifications in plant production and allocation of C among plant pools, is an important source of uncertainty when predicting future forest function. Utilizing 10 yr of data from the Duke free-air CO(2) enrichment site, we evaluated the dynamics and distribution of plant C. *Discrepancy between heights measured for this study and previously calculated heights required revision of earlier allometrically based biomass determinations, resulting in higher (up to 50%) estimates of standing biomass and net primary productivity than previous assessments. *Generally, elevated [CO(2)] caused sustained increases in plant biomass production and in standing C, but did not affect the partitioning of C among plant biomass pools. Spatial variation in net primary productivity and its [CO(2)]-induced enhancement was controlled primarily by N availability, with the difference between precipitation and potential evapotranspiration explaining most interannual variability. Consequently, [CO(2)]-induced net primary productivity enhancement ranged from 22 to 30% in different plots and years. *Through quantifying the effects of nutrient and water availability on the forest productivity response to elevated [CO(2)], we show that net primary productivity enhancement by elevated [CO(2)] is not uniform, but rather highly dependent on the availability of other growth resources.
McCarthy
Heather R
HR
Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27708, USA. heather.mccarthy@uci.edu
Oren
Ram
R
Johnsen
Kurt H
KH
Gallet-Budynek
Anne
A
Pritchard
Seth G
SG
Cook
Charles W
CW
Ladeau
Shannon L
SL
Jackson
Robert B
RB
Finzi
Adrien C
AC
D018533:Biomass; D002244:Carbon / Q000502:physiology*; D002245:Carbon Dioxide / Q000502:physiology*; D009584:Nitrogen / Q000502:physiology*; D010788:Photosynthesis / Q000502:physiology*; D018526:Plant Transpiration; D011891:Rain; D014197:Trees / Q000254:growth & development / Q000502:physiology*; D014867:Water / Q000502:physiology*
D014867:Water; D002245:Carbon Dioxide; D002244:Carbon; D009584:Nitrogen