Aboveground sink strength in forests controls the allocation of carbon below ground and its [CO2]-induced enhancement.

Journal Article (Journal Article)

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 (LD) to account for differences in growing-season length. Moreover, elevated [CO2]-induced enhancement of TBCA in the combined data decreased from approximately 50% (700 g C m(-2) y(-1)) at the lowest LD to approximately 30% (200 g C m(-2) y(-1)) at the highest LD. 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.

Full Text

Duke Authors

Cited Authors

  • Palmroth, S; Oren, R; McCarthy, HR; Johnsen, KH; Finzi, AC; Butnor, JR; Ryan, MG; Schlesinger, WH

Published Date

  • December 11, 2006

Published In

Volume / Issue

  • 103 / 51

Start / End Page

  • 19362 - 19367

PubMed ID

  • 17159142

Pubmed Central ID

  • PMC1748231

Electronic International Standard Serial Number (EISSN)

  • 1091-6490

International Standard Serial Number (ISSN)

  • 0027-8424

Digital Object Identifier (DOI)

  • 10.1073/pnas.0609492103


  • eng