Publication Date:
2022-05-26
Description:
Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 111 (2014): 8856-8860, doi:10.1073/pnas.1320761111.
Description:
The traditional view of forest dynamics originated by Kira, Shidei, and Odum suggests a decline in net primary productivity (NPP) in ageing forests due to stabilized gross primary productivity (GPP) and continuously increased autotrophic respiration (Ra). The validity of these trends in GPP and Ra is, however, very difficult to test because of the lack of long-term ecosystem-scale field observations of both GPP and Ra. Ryan and colleagues have proposed an alternative hypothesis drawn from site-specific results that aboveground respiration and belowground allocation decreased in ageing forests. Here we analyzed data from a recently assembled global database of carbon fluxes and show that the classical view of the mechanisms underlying the age-driven decline in forest NPP is incorrect and thus support Ryan’s alternative hypothesis. Our results substantiate the age-driven decline in NPP, but in contrast to the traditional view, both GPP and Ra decline in ageing boreal and temperate forests. We find that the decline in NPP in ageing forests is primarily driven by GPP, which decreases more rapidly with increasing age than Ra does, but the ratio of NPP/GPP remains approximately constant within a biome. Our analytical models describing forest succession suggest that dynamic forest ecosystem models that follow the traditional paradigm need to be revisited.
Description:
We thank all site investigators, their funding agencies and the various regional flux networks (Afriflux, AmeriFlux, AsiaFlux, CarboAfrica, CarboEurope-IP, ChinaFlux, Fluxnet-Canada, KoFlux, LBA, NECC, OzFlux, TCOS-Siberia, and USCCC) and the Fluxnet project, whose support is essential for obtaining the measurement data without which this synthesis analysis would not be possible. The collection of the original global database was funded by the Research Foundation - Flanders (FWO-Vlaanderen) who supported S.L. with a post-doctoral fellowship and a research grant (FWO 1.5037.07N). J. Tang was partially supported by U.S. Department of Energy the Office of Biological and Environmental Research (DE-SC0006951), and National Science Foundation (DBI-959333 and AGS-1005663).
Description:
2014-12-02
Keywords:
Succession
;
Chronosequence
;
Forest dynamics
;
Photosynthesis
;
Respiration
;
Carbon flux
;
Carbon use efficiency
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
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