From plant plasticity to demography: modelling plant responses to global change across timescales

Plants have a high capacity to both adapt to long term climate condition and to acclimate in response to short-term environmental changes. Superimposed on these individual plant responses, changes in environmental conditions and competition amongst individuals drive shifts in species composition and all these together drive changes in ecosystem function. Historically, vegetation models represented plants as rigid, with little or no capacity to react to change, with a basic representation of biome shift, leading to sometimes unexpected and unrealistic predictions of vegetation shifts under future conditions. Since, models have advanced both in terms of plasticity and vegetation dynamics representations although to some extent on parallel tracks, with little exploration of the interactions between the two. Using the QUINCY land surface model, we explore the implications of representing plant plasticity on both short and long timescales as well as the effect of competitive pressures. We use data from networks of manipulative experiments – DrougthNet and the Nutrient Network – to disentangle the extent to which plastic responses to stressors are general across the globe or adapted to specific conditions. The drought and nutrient manipulation also give us the opportunity to explore concepts around belowground competition for resources, which has been included in models to a far lesser extent than aboveground competition for light. While questions around the effect of increased model complexity remain, increased ecological realism and the inclusion of all relevant processes and their interaction improves our understanding and predictive capability of future vegetation dynamics.