The terrestrial vegetation carbon balance is controlled not just by photosynthesis, but by respiration, carbon allocation, turnover (comprising litterfall, background mortality and disturbances) and wider vegetation dynamics. However, these processes have proved extremely challenging to observe and quantify at large scales and over long time periods. Existing large-scale empirical products of vegetation carbon fluxes and stocks have large uncertainties and/or data gaps. Furthermore, the observed changes in vegetation properties are often the result of a number of interacting processes and can be driven by changes in CO2, climate, natural disturbances or human activities. Thus, our current understanding of the environmental controls on vegetation dynamics and properties, and in turn their impact on carbon stocks in biomass and soils, is limited and the behaviour of large-scale vegetation models remains underconstrained. This gives rise to high uncertainty as to whether terrestrial vegetation will continue to act as a carbon sink under future environmental changes, or whether increases in autotrophic respiration or carbon turnover, e.g. through accelerated background tree mortality or by more frequent and more severe disturbance events (e.g. drought, fire, insect epidemics), will counteract this negative feedback to climate change. We welcome contributions that make use of observational approaches, vegetation models, or model-data integration techniques to advance understanding of the effects of environmental change on vegetation dynamics and carbon stocks and fluxes at local, regional or global scales and/or at long time scales.
Keynote: Prof Shaun Quegan, University of Sheffield.