Characterizing Land Use Impacts on Functional Plant Diversity for Life Cycle Assessments

Decision support tools such as life cycle assessment (LCA) increasingly aim to account for impacts on biodiversity. While taxonomic measures like species richness have been implemented, they do not fully grasp the impacts on ecosystem functioning. Functional diversity, derived from the species' traits, is more representative of ecosystem processes. This study provides a framework for developing characterization factors for functional diversity as affected by land use. It exploits the large databases on plant traits and species composition that have recently become available and allow bringing biodiversity impact assessment to the next level. Three functional diversity indices therein describe different aspects of functional diversity, namely richness, evenness, and divergence. Applying our framework to Germany as a proof of concept, we show significant losses in functional plant diversity when converting natural forests to agricultural land use. Consistently across different forests and agricultural systems, functional richness decreases steeply and functional divergence moderately upon occupation. In contrast, functional evenness exhibits opposite trends. The resulting characterization factors are likely to be representative of temperate regions. The framework is flexible and applicable to larger scales and other impact categories. As such, it facilitates harmonizing biodiversity impact assessments and better represents ecosystem functioning by incorporating functional diversity.