Bridging disciplinary boundaries with the interdisciplinary land-use model SECLAND
Authors: Egger Claudine , Mayer Andreas , Bertsch-Hörmann Bastian , Gaube Veronika 
Published: March 2024

Land-use and climate change are major drivers of environmental change at global and regional scales, posing major threats to biodiversity, ecosystem services and biogeochemical processes and thus to ecosystem functioning. Changing climatic conditions, such as changes in temperature, precipitation patterns and frequency of extreme events, as well as changing societal preferences and socio-economic trends such as increasing demand for organic products, changing subsidy frameworks or prices for food, feed and fiber will force land users to reassess and adapt their land-use decisions. This will require models that can take into account the interactions and systemic feedbacks between changes in climate and land use, which will affect agricultural production and natural ecosystem systems.We developed the SECLAND agent-based model (ABM) to link biophysical and societal drivers of land-use change and, through subsequent coupling with other models, their effects on ecosystem change. The SECLAND ABM represents land-use transitions between gradients: shifts in crop cultivation, intensity changes and land abandonment followed by forest transition. Land-use change is the result of decision-making processes of individual farm and forest agents. These agents represent real world actors who make decisions to achieve and maintain well-being, which is defined as a balance between (minimum) income and (maximum) workload. In addition, their worldview, respectively intrinsic motivation is an important driver of their decision-making which determines their preferences for certain decisions but may also influence their perceptions of extreme events as climate change threats and inertia towards adaptation measures. By combining different scenarios, we can assess the individual and combined impacts of changing socio-economic and climatic conditions on land-use decisions.In several studies, we have applied the model to the LTSER region Eisenwurzen in Austria. The LTSER platform provides a variety of environmental data for the study region, which we supplemented with quantitative census and qualitative data from interviews and workshops with regional decision makers. This participatory modelling approach improves the adaptation and calibration of the model to the conditions of the study region, but the collaboration with stakeholders further facilitates the development of relevant future scenarios as well as the evaluation of the modelling results.In a holistic approach, the modelling process focuses on the clarification of interdisciplinary interfaces and parameters, and on stakeholder involvement to ensure that the results are relevant and usable. The SECLAND ABM, developed by an interdisciplinary team, is a land-use model designed for the integrated analysis of study regions and for interfacing with various other models. Model trajectories from previous applications of the SECLAND ABM for the Eisenwurzen show strong extensification trends combined with land abandonment and forest transition until 2050. We used the spatially explicit land use maps as an interface to (soft) couple the modeling results with biophysical models to assess biodiversity shifts with a species distribution model (SDM), the quality of soil and surface water with a Soil &amp; Water Assessment Tool (SWAT), nitrogen flows with a Landscape De-Nitrification De-Composition (LDNDC) model and changes in ecosystem services such as carbon stored in biomass (HANPP).