Uncertainties in the application of the species area relationship for characterisation factors of land occupation in life cycle assessment

Abstract

Purpose Uncertainties in land use damage modeling are recognized, but hardly quantified in life cycle assessment (LCA). The objective of this study is to analyze the influence of various key assumptions and uncertainties within the development of characterisation factors (CFs) for land use in LCA. We assessed the influence on land use CFs of (1) parameter uncertainty and (2) the choice for a constant or land use-specific species accumulation factor z and including or excluding regional effects. Methods A model framework was developed to analyze the uncertainties of CFs for six land use types and three agricultural practices. The CFs are expressed as potential disappeared fraction (PDF) of vascular plant species based on the species area relationship (S=c.A z ). The species area relationship describes the relation between the species number and area size, with help of the species accumulation factor z and the species richness factor c. A dataset representative for Great Britain was used to quantify both modeling choices and parameter uncertainty. Modeling choices were analyzed by defining three coherent scenarios, based on cultural theory perspectives. The parameter uncertainties of average species number and species accumulation factor z were quantified using Monte Carlo simulation.Results and discussion Pair-wise comparison of the CFs shows that 68-85% of the CFs significantly differ from each other within each perspective. It is found that the ranking of organic, less intensive, and intensive land practices of each land use type is unaltered by the chosen model scenario. However, the absolute values of the CFs can change from negative to positive scores with an average difference of 0.8 PDF between the two extreme perspectives, i.e., individualistic and egalitarian. The difference between these scenarios is for 40% explained by the choice in z and for 60% by the choice in including regional effects. Within the egalitarian and hierarchist perspective the species accumulation factor z is for more than 80% responsible for the parameter uncertainty. Conclusions Modeling choices and uncertainties within the species area relationship hardly change the ranking of the different land practices but largely influence the absolute value of the CFs for land use. The absolute change in the land use CFs can change the interpretation of land use impacts compared with other stressors such as climate change.

Multi‐criteria assessment of yellow, green, and woody biomasses: pre‐screening of potential biomasses as feedstocks for biorefineries

“…measured in terms of Potential Disappeared Fraction (PDF) of species as the indicator, or also termed Characterization Factor (CF), is another important parameter that should be considered in a system‐wide sustainability assessment. De Schryver et al proposed that the characterization factor for arable land as: 0.36 (for organic), 0.44 (conventional, less intensive), 0.79 (conventional, intensive), which implies that the careful consideration on effects of land use, expansion, and intensification are needed. Smeets et al added that biodiversity in Miscanthus and switchgrass fields are generally higher compared to conventional annual crops, especially in the early establishment period.…”

Environmental impacts of organic and conventional agricultural products – Are the differences captured by life cycle assessment?

“…Of these 18 studies, nine studies assessed a wider range of environmental impacts that can be routinely assessed today using LCA (Williams et al, 2006(Williams et al, , 2010de Backer et al, 2009;Nemecek et al, 2011a;Alig et al, 2012;Leinonen et al, 2012a,b;Abeliotis et al, 2013;Villanueva-Rey et al, 2014). Biodiversity impacts were assessed in Alig et al (2012) and Nemecek et al (2011a), using the LCIA-method "SALCA-BD" (Jeanneret et al, 2009(Jeanneret et al, , 2014, in Guerci et al (2013) using biodiversity damage scores as proposed by De Schryver et al (2010), and in Haas et al (2001) where impact on biodiversity was qualitatively judged based on self-defined criteria. However, all four studies the impact on biodiversity was assessed for only part of the life cycle of the specific products and was determined on a per area unit only except in Guerci et al (2013) where land use impacts were related to the production of 1 kg of milk.…”

UNEP-SETAC guideline on global land use impact assessment on biodiversity and ecosystem services in LCA

“…However, weightings of ecosystem services midpoints as well as many decisions done along the development of LCIA are clearly a matter of value choices. Further developments should make them consistently transparent for archetypical cultural perspectives (Hofstetter 1998;De Schryver et al 2010).…”