Open AccessCanopy leaf area constrains [CO 2 ]-induced enhancement of productivity and partitioning among aboveground carbon pools
Author(s) -
Heather R. McCarthy,
Ram Oren,
Adrien C. Finzi,
Kurt H. Johnsen
Publication year - 2006
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.0609448103
Subject(s) - primary production , environmental science , canopy , productivity , biomass (ecology) , temperate rainforest , leaf area index , carbon sequestration , growing season , agronomy , temperate climate , ecosystem , atmospheric sciences , temperate forest , nutrient , ecology , carbon dioxide , biology , economics , macroeconomics , geology
Net primary productivity (NPP) is enhanced under future atmospheric [CO2 ] in temperate forests representing a broad range of productivity. Yet questions remain in regard to how elevated [CO2 ]-induced NPP enhancement may be affected by climatic variations and limiting nutrient resources, as well as how this additional production is distributed among carbon (C) pools of different longevities. Using 10 years of data from the Duke free-air CO2 enrichment (Duke FACE) site, we show that spatially, the major control of NPP was nitrogen (N) availability, through its control on canopy leaf area index (L ). Elevated CO2 levels resulted in greaterL , and thus greater NPP. After canopy closure had occurred, elevated [CO2 ] did not enhance NPP at a givenL , regardless of soil water availability. Additionally, using published data from three other forest FACE sites and replacingL with leaf area duration (L D ) to account for differences in growing season length, we show that aboveground NPP responded to [CO2 ] only through the enhancement ofL D . For broadleaf forests, the fraction of aboveground NPP partitioned to wood biomass saturated with increasingL D and was not enhanced by [CO2 ], whereas it linearly decreased for the conifer forest but was enhanced by [CO2 ]. These results underscore the importance of resolving [CO2 ] effects onL to assess the response of NPP and C allocation. Further study is necessary to elucidate the mechanisms that control the differential allocation of C among aboveground pools in different forest types.