Navigation and service


Soil-plant-systems

Transpiration by plants is an important part of the terrestrial water cycle and of the energy exchanges across the land-atmosphere interface. The transpiration rate is determined by the atmospheric demand and by the soil moisture status in the soil profile. The relation between transpiration rate and soil water availability in soil-vegetation-atmosphere-transfer models is represented by empirical functions. Since root water uptake and subsurface soil moisture are difficult to measure, the validity of these empirical functions is limited. This is especially the case for natural vegetation systems with deep and heterogeneous rooting systems and for dry or semi-arid conditions where plants and rooting systems developed different strategies to respond to water stress.

A better mechanistic description of the root water uptake is therefore of direct scientific interest. As a result of this improved description, the interaction between the land surface and the atmosphere can be predicted better. This improvement is important for predicting the consequences of global change on regional scale climate. Analyses of regional scale climate models show that the coupling between the land surface and atmosphere is one of the main sources of uncertainty. Since water vapour and CO2, respectively, leave and enter the plant through the same gates, the stomata, it is evident that a closure of stomata due to water shortage in the soil is associated with a decrease in carbon assimilation. A more mechanistic description of the root water uptake and the occurrence of water stress will therefore also improve the prediction of the effect of dry soil conditions on carbon assimilation and biomass production. A good understanding of the impact of water availability in the soil on root water uptake and biomass production is of key importance to improve model predictions of the impact of changing cropping patterns, e.g. for biomass production, on the water cycle and the availability of water resources. It is also crucial to assess the potential for new cropping systems in regions where agricultural productivity is low because of water shortage due to climatic or soil physical reasons. Finally, a model that explicitly considers the architecture and properties of the plant root system in order to assess the root water uptake as a function of the soil water availability can be used to assess a priori the resilience of crop types with altered root architectures and root properties.


Contact

Questions on this project should be directed to HPSC TerrSys's Scientific Director.


An initiative of