You are here

The changing global carbon cycle: linking plant–soil carbon dynamics to global consequences. Special Feature – Essay review plant – soil interactions and the carbon cycle

TitleThe changing global carbon cycle: linking plant–soil carbon dynamics to global consequences. Special Feature – Essay review plant – soil interactions and the carbon cycle
Publication TypeJournal Article
Year of Publication2009
AuthorsChapin III, SF, McFarland, J, McGuire, DA, Euskirchen, ES, Ruess, RW, Kielland, K
JournalJournal of Ecology
Volume97
Pagination840–850
Abstract

Summary1. Most current climate–carbon cycle models that include the terrestrial carbon (C) cycle are basedon a model developed 40 years ago by Woodwell & Whittaker (1968) and omit advances in biogeochemicalunderstanding since that time. Their model treats net C emissions from ecosystems as thebalance between net primary production (NPP) and heterotrophic respiration (HR, i.e. primarilydecomposition).2. Under conditions near steady state, geographic patterns of decomposition closely match thoseof NPP, and net C emissions are adequately described as a simple balance of NPP and HR (theWoodwell-Whittaker model). This close coupling between NPP and HR occurs largely because oftight coupling between C and N (nitrogen) cycles and because NPP constrains the food available toheterotrophs.3. Processes in addition to NPP and HR become important to understanding net C emissions fromecosystems under conditions of rapid changes in climate, hydrology, atmospheric CO2, land cover,species composition and&\#8260; or N deposition. Inclusion of these processes in climate–C cycle modelswould improve their capacity to simulate recent and future climatic change.4. Processes that appear critical to soil C dynamics but warrant further research before incorporationinto ecosystem models include below-ground C flux and its partitioning among roots, mycorrhizasand exudates; microbial community effects on C sequestration; and the effects oftemperature and labile C on decomposition. The controls over and consequences of these processesare still unclear at the ecosystem scale.5. Carbon fluxes in addition to NPP and HR exert strong influences over the climate system underconditions of rapid change. These fluxes include methane release, wildfire, and lateral transfers offood and fibre among ecosystems.6. Water and energy exchanges are important complements to C cycle feedbacks to the climatesystem, particularly under non-steady-state conditions. An integrated understanding of multipleecosystem–climate feedbacks provides a strong foundation for policies to mitigate climate change.7. Synthesis. Current climate systems models that include only NPP and HR are inadequate underconditions of rapid change. Many of the recent advances in biogeochemical understanding are sufficientlymature to substantially improve representation of ecosystem C dynamics in these models.

DOI10.1111/j.1365-2745.2009.01529.x