Page 248 - Materials Chemistry, Second Edition

232 4 Life Cycle Impact Assessment

processes that can extend over long periods. It can be accordingly difficult to find
suitable indicators with the help of which quantification is possible. 148)
The published method of Mila i Canals et al. 149) , currently widely discussed,
refers to the safeguard subject ‘life support function (LSF)’ of agricultural and
forestry areas. The LSF is calculated by building the difference between the ‘soil
organic matter (SOM)’ – calculated based on the carbon content of soil at the
beginning and at the end of specified land use. Thus the LSF mirrors the difference
of soil fertility reduced to the indicator ‘change in carbon content’ between two
states. For consequential LCA this may be a useful indicator, for attributional LCA
assumptions concerning the reference situation are necessary.
This concept was modified by Brandao and Mil` a i Canals 150) : Instead of the LSF
the indicator ‘soil organic carbon’ (SOC) is directly used and referring to Koellner
et al. 151),152) ; the reference situation is defined as the (quasi-)natural vegetation
depending on the geographical location and thus biomes and ecoregions are
considered. The SOC of the vegetation under study (forest or crop) and the
reference situation is calculated based on IPCC data, 153),154) which correlate specified
vegetation with the carbon content of the soil. However the geographic resolution
and the differentiation of agricultural crops and forests are low.
The difference in carbon content addresses, according to the authors, the
biological production potential.
An enumeration of possible indicators to the impacts specified above has led to
a debate on the correct progress. 155) Udo de Haes criticises the absence of a critical
discussion on which aspects, if any, of land use are compatible with substantial
elements of an LCA (as for instance quantitative analysis ‘from cradle to grave’, to
the comparison on the basis of a fU, generic – thus not local – treatment of space,
and to flow equilibria). Further elements that absolutely do not fit into an LCA
should be identified, and proposals should be prepared on how these aspects or
impacts could be handled outside of LCA. However, Mil` a i Canals et al.counter
that site-dependent characterisation factors are increasingly considered in the
impact assessment; a flow equilibrium can be established and kept by appropriate
temporal average values; (still) no specific indicators have been suggested as on
date; however probably the most important impacts have been named, at least the
most important: the variety of species. It is stressed, by the Dutch guideline 156) that
2
the admission of an unweighted inventory parameter surface × time (m a) is better
than to completely omit land use in the impact assessment. It is only one step from
here to land use weighted by means of hemerobic levels.

148) Koellner and Scholz (2007).
149) Mil´ a i Canals, Romanya and Cowell (2007).
150) Brandao and Mil` a i Canals (2013).
151) Koellner et al. (2013a).
152) Koellner et al. (2013b).
153) IPCC (2003).
154) IPCC (2006).
155) Udo de Haes (2006), Guin´ ee et al. (2006) and Mil` a I Canals et al. (2007b).
156) Guin´ ee et al. (2002).