Simulating crop damages due to abiotic events: case studies using the AbioticDamage model library

Abstract: One of the largest consequences of projected climate change is an increased frequency of extreme weather events or conditions. They impact heavily on crops as they are out of the range of variability which crops are adapted to. As an example, air temperature is a driving variable involved in the simulation of plant development, and it is used for estimating both crop development and photosynthesis limitation at any given level of intercepted solar radiation. Although with different algorithms, these processes are basically included in all crop simulation models. The reduction of leaf area index or the possible death of the plant due to frost are usually not included in crop growth models, as well as the yield losses due to pre-flowering cold shocks inducing spikelet sterility, although these processes are driven by the same variable (temperature). Another example is ozone concentration in the air; it has traditionally been ignored in modelling because taken for constant in a given environment, hence assuming crops being adapted to its concentration. However, if ozone concentration changes, and given its toxicity, its impact on crop growth must be included in models used for scenario analysis. The impact of many extreme events or conditions is usually not included in the simulation models used for the analysis of crop response to climate change scenarios. This is a limitation which needs to be overcome because such conditions are key elements characterizing the weather scenarios as estimated by global circulation models. The .NET C# library AbioticDamage implements models to simulate events the plant is not physiologically prepared to deal with. Models for the simulation of the main damages affecting the production of herbaceous crops due to abiotic factors are implemented in an extensible library, to be linked to crop development and growth models. It implements six categories of damages: frost, cold-induced spikelet sterility, lodging, ozone, salinity, and heat-induced spikelet sterility: The modelling solutions are taken from peer reviewed sources. The component encapsulates the ontology of the variables and parameters defined which is also used to implement optional run-time data quality tests following the design-by-contract approach. The architecture allows for alternate models to simulate the impact of abiotic factors, and it permits extension by third parties. The component is provided together with the documentation of all the equations, the documentation of the code, a set of unit tests, where all the sub-models implemented were tested against the numerical results obtained with the same inputs in a different environment. In this paper we present two case studies where the component AbioticDamage was run linked to the component CropML (Crop Model Library). Gridded weather data with coverage of 27 member states of the European Union (EU-27) for the years 2002 - 2008 were used to simulate abiotic stresses: frost and spikelet sterility on winter wheat and rice grain yields, respectively. Results are discussed in terms of deviation of simulated yields from simulations run without accounting for the impact of stresses. Year 2002 is signalled for severe frost damages affecting France and other important winter wheat EU-27 producing countries. For rice, simulations indicate a roughly constant degree of spikelet sterility (about 5%) affecting the cultivations of Eastern Europe countries. For Mediterranean countries, summer temperature falls may cause severe sterility problems in some years (e.g., 2007). The case studies presented are illustrative of the type of output attainable for dedicated tools for simulation of abiotic damages in cultivated plant species, and their usefulness to interpret the impact of climatic alterations that have occurred in Europe in the last years.

JRC.DG.G.3 - Monitoring agricultural resources