Ecosystems supply society with a range of resources (mainly through biomass) and services (related to the society value of preserving landscape and biodiversity). Biomass production in terrestrial ecosystems goes hand in hand with the depletion of another important resource, water. Groundwater resources and ecosystems relying on groundwater are facing increasing pressure from land-use and groundwater extraction. Many ecosystems also affect the exchange of mass and energy in the surface atmospheric layer with consequences on local and global climate, leading to possible feedbacks between their adaptation mechanisms and environmental change. Understanding the general principles behind the self-organisation of ecosystems may help predict some of the consequences of environmental change for both ecosystem services and water resources. The ability to make such predictions would greatly benefit society, as it would contribute to planning a sustainable future for ecosystems and better management of water related issues, such as droughts or floods.

Environmental change can be observed at different spatial and temporal scales and encompass various system properties, such as climate, land use, topography and soil properties. Some of the changes that we are facing are predictable to a certain extent (e.g. the rise in surface temperature) and some are direct consequences of human activities (e.g. the degree of deforestation, landscape fragmentation).

However, most of our existing models are ill-prepared for decision making in a changing environment, mainly because they are based on parameter calibrations derived from past observations and the assumption of stationarity. Nevertheless, such models are commonly used for making predictions under change, often well beyond the range of conditions they were calibrated for. The effects of increasing atmospheric CO2 concentrations in particular cannot be deduced from current observations, as there are presently no ecosystems adapted to the CO2 concentrations that we expect in the near future. Vegetation acclimation and the likely altered dynamics of species competition and ecosystem disturbances in response to environmental change are inherently difficult to capture in present models.

In order to address some of the challenges posed by environmental change, we need new modelling approaches that do not rely on calibration of parameters that are likely to change in the future and we need to extend our knowledge about how vegetation, soils, biogeochemical cycles, and water resources are going to respond to changing boundary conditions. Investigating these complex links will be essential for explaining process and pattern dynamics and improve modelling capabilities.

This session aims to bring together modellers, experimentalists and empiricists in order to expose new understanding and present new avenues to approach the challenges posed by environmental and anthropogenic change.

Solicited authors: Rob Wilby, Uwe Ehret, Alberto Montanari, Praveen Kumar