The Digital Twin Component of forests (Forest DTC) aims to create a digital representation of forests, maximising the use of Earth observation (EO) data at high spatial resolution, corresponding to the resolution of Sentinel-2 Multispectral Instrument imagery.
As a spatially explicit simulation tool, Forest DTC will model the evolution of forest systems under diverse scenarios, including varying climate conditions, forest management strategies and policies. The implementation of Forest DTC focuses on modelling forest growth and the carbon cycle at Sentinel-2’s highest available spatial resolution (10 m). The output temporal resolution for the forest state is one year, with growth simulations based on daily weather data. A yearly cycle is also incorporated to simulate forest management actions.
The digital replica of forests will provide information on structural details (species composition, tree density, basal area, dominant tree height) and productivity data (site type, biomass estimates, annual tree growth rates and productivity metrics like GPP and NEE). Aligning with the objectives of DestinE, Forest DTC aims to provide DestinE users with tailored information, services, models, scenarios, forecasts and visualisations. The initial state of forests will be retrieved from EO data and the forest maps will be updated with the most recent EO data to account for possible disturbances (see the figure).
User needs for a forest digital twin were mapped in a precursor project, completed in 2021. During the ongoing Forest DTC, we will update the user needs and requirements from the precursor stage, incorporate new data sources like hyperspectral imagery and tree maps based on individual tree detection. Additionally, we will include components, such as forest fire fuel and pest damage risk. The system will be modular, allowing for the inclusion of user- or biome-specific growth models, management simulators and end-user extensions.
Although designed as a global tool, the DTC of forests will initially focus on forests in Europe, laying the groundwork for the broader application of Forest DTC worldwide. Four demonstration use cases will be developed across Europe within the project framework:
- assessment of forest biotic disturbances,
- evaluation of fire fuel and hazards,
- impact of management on forest resources and carbon balance,
- monitoring and modelling of forests using hyperspectral data and tree-level information across a gradient from tropical to continental regions.
Forest DTC may develop suitable interactions with the other EO-based Digital Twin Components to exchange relevant information and services. However, in the coming years, a key challenge will be integrating the vastly different spatial and temporal resolutions of the Forest DTC with those of other DTCs of the ESA DTE programme. To address this, the information provided by the DTCs should be accessed in a standardised manner. In the future, all the DTCs are likely to be available via DESP to all DestinE users, enabling the users to understand the future of forests better by testing different ‘what if’ scenarios, for instance.