Hemeroby as an impact category indicator for the integration of land use into life cycle (impact) assessment

As most of the impact categories modelled in Life Cycle (Impact) Assessment, land use is influenced by an immense number of different impacts forming a complex interaction network. At present, there is no common consensus on the best practice for quantification of land use in LCA. However, land use and its consequences for biodiversity and ecosystem services are currently subject to intense public debate. Here, we review relevant methodology proposed to date with special reference to the hemeroby concept to identify a consistent method that captures the complexity of land use without oversimplification and loss of crucial information.

With the application of a system of seven ordinal classes, the diversity of naturalness in forestry and agricultural production systems can be adequately characterised. The applicability of the classification system of the hemeroby concept was reviewed and aspects in need of further development and method refinement were identified. Furthermore, the hemeroby concept was compared to other common concepts for the integration of land use into LCIA.

The hemeroby concept was identified as an appropriate approach to quantify the safeguard subject naturalness as an LCIA indicator. In addition, it addresses subjects like biodiversity and intact ecosystems. Characterising the quality of utilised land by classes encompassing ranges on an ordinal scale offers considerable merits in comparison with single value systems on a cardinal scale. Such systems tend to oversimplify the highly complex variable land use by assuming a single quantifiable ecological indicator (e.g. soil carbon content or relative α-biodiversity) as representative proxy. In contrast to this, the hemeroby concept offers an approach that is able to retain sufficient complexity of the information available for a particular area, yet condense this information so that it may be modelled for LCA purposes without loss of crucial data.

Among all the methods currently available for the quantification of land use, the hemeroby concept is the most promising in terms of practicality of the actual method and quality of the output data. The classification into hemeroby classes is superior at capturing the complexity of land use. The method has been applied successfully in the area of European forests and agriculture. However, global availability of spatial hemeroby data and their compatibility with the criteria stipulated here needs to be evaluated and further developed as necessary. Other approaches focus on a different safeguard subject, thus narrowing the scope of land use as an impact indicator.