Below-ground carbon flux and partitioning: global patterns and response to temperature
Article first published online: 3 SEP 2008
© 2008 The Authors. Journal compilation © 2008 British Ecological Society
Volume 22, Issue 6, pages 941–954, December 2008
How to Cite
Litton, C. M. and Giardina, C. P. (2008), Below-ground carbon flux and partitioning: global patterns and response to temperature. Functional Ecology, 22: 941–954. doi: 10.1111/j.1365-2435.2008.01479.x
- Issue published online: 3 NOV 2008
- Article first published online: 3 SEP 2008
- Received 17 November 2007; accepted 8 August 2008Handling Editor: Lindsey Rustad
- below-ground carbon cycling;
- below-ground net primary production (BNPP);
- carbon allocation;
- gross primary production (GPP);
- mean annual temperature (MAT);
- total below-ground carbon flux (TBCF)
- 1The fraction of gross primary production (GPP) that is total below-ground carbon flux (TBCF) and the fraction of TBCF that is below-ground net primary production (BNPP) represent globally significant C fluxes that are fundamental in regulating ecosystem C balance. However, global estimates of the partitioning of GPP to TBCF and of TBCF to BNPP, as well as the absolute size of these fluxes, remain highly uncertain.
- 2Efforts to model below-ground processes are hindered by methodological difficulties for estimating below-ground C cycling, the complexity of below-ground interactions, and an incomplete understanding of the response of GPP, TBCF and BNPP to climate change. Due to a paucity of available data, many terrestrial ecosystem models and ecosystem-level studies of whole stand C use efficiency rely on assumptions that: (i) C allocation patterns across large geographic, climatic and taxonomic scales are fixed; and (ii) c. 50% of TBCF is BNPP.
- 3Here, we examine available information on GPP, TBCF, BNPP, TBCF : GPP and BNPP : TBCF from a diverse global data base of forest ecosystems to understand patterns in below-ground C flux and partitioning, and their response to mean annual temperature (MAT).
- 4MAT and mean annual precipitation (MAP) covaried strongly across the global forest data base (37 mm increase in MAP for every 1 °C increase in MAT). In all analyses, however, MAT was the most important variable explaining observed patterns in below-ground C processes.
- 5GPP, TBCF and BNPP all increased linearly across the global scale range of MAT. TBCF : GPP increased significantly with MAT for temperate and tropical ecosystems (> 5 °C), but variability was high across the data set. BNPP : TBCF varied from 0·26 to 0·53 across the entire MAT gradient (−5 to 30 °C), with a much narrower range of 0·42 to 0·53 for temperate and tropical ecosystems (5 to 30 °C).
- 6Variability in the data sets was moderate and clear exceptions to the general patterns exist that likely relate to other factors important for determining below-ground C flux and partitioning, in particular water availability and nutrient supply. Still, our results highlight global patterns in below-ground C flux and partitioning in forests in response to MAT that in part confirm previously held assumptions.