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Aboveground sink strength in forests controls the allocation of carbon below ground and its [CO₂]-induced enhancement
- Abstract::
- The partitioning among carbon (C) pools of the extra C captured under elevated atmospheric CO₂ concentration ([CO₂]) determines the enhancement in C sequestration, yet no clear partitioning rules exist. Here, we used first principles and published data from four free-air CO₂ enrichment (FACE) experiments on forest tree species to conceptualize the total allocation of C to below ground (TBCA) under current [CO₂] and to predict the likely effect of elevated [CO₂]. We show that at a FACE site where leaf area index (L) of Pinus taeda L. was altered through nitrogen fertilization, ice-storm damage, and droughts, changes in L, reflecting the aboveground sink for net primary productivity, were accompanied by opposite changes in TBCA. A similar pattern emerged when data were combined from the four FACE experiments, using leaf area duration (L(D)) to account for differences in growing-season length. Moreover, elevated [CO₂]-induced enhancement of TBCA in the combined data decreased from approximately equal to 50% (700 g C m⁻² y⁻¹) at the lowest L(D) to approximately equal to 30% (200 g C m⁻² y⁻¹) at the highest L(D). The consistency of the trend in TBCA with L and its response to [CO₂] across the sites provides a norm for predictions of ecosystem C cycling, and is particularly useful for models that use L to estimate components of the terrestrial C balance.
- Author(s):
- Palmroth, S. , Oren, R. , McCarthy, H.R. , Johnsen, K.H. , Finzi, A.C. , Butnor, J.R. , Ryan, M.G. , Schlesinger, W.H.
- Subject(s):
- forest plantations , Pinus taeda , deciduous forests , carbon dioxide , elevated atmospheric gases , primary productivity , leaf area index , nitrogen , nutrient availability , nitrogen fertilizers , fertilizer application , soil respiration , roots , root growth , North Carolina , Wisconsin , Tennessee , Italy
- Description:
- Includes references
- Source:
- Proceedings of the National Academy of Sciences of the United States of America 2006 Dec. 19, v. 103, no. 51
- Language:
- English
- Year:
- 2006
- Collection:
- Journal Articles, USDA Authors, Peer-Reviewed
- File:
- Download [PDF]
- Rights:
- Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.
