LCA Food 2012 in Saint Malo, France! - Manifestations et colloques ...

PLENARY SESSION 3: METHODS FOR BIODIVERSITY AND SOIL QUALITY 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
Assessing land use impacts on biodiversity on a regional scale: the case
of crop production in Kenya
Laura de Baan 1* , Michael Curran 2 , Stefanie Hellweg 2 , Thomas Koellner 3
1 NSSI, Institute for Environmental Decisions, ETH Zurich, Universitätstr. 22, 8092 Zurich, Switzerland
2 ESD, Institute for Environmental Engineering, ETH Zurich, Schafmattstr. 6, 8093 Zurich, Switzerland
3 Professorship of Ecological Services, University of Bayreuth, Universitätsstr. 30, 95440 Bayreuth, Germany
Corresponding author. E-mail: laura.debaan@ethz.env.ch
ABSTRACT
In current Life Cycle Impact Assessment (LCIA), impacts of land use on biodiversity are often assessed at a local (e.g. field) scale.
The relevance of these local impacts is often limited, as species that are not able to survive on agricultural land may persi st in adjacent
undisturbed areas. However, if habitat is scarce on a regional scale, the risk of regional or even global extinction increases. Here,
we present a method to upscale local land use impacts in LCIA to the ecoregional scale using an adapted species-area relationship
model. This model is applied to land use in Kenya, where conversion of natural habitats to small and large-scale farms is threatening
areas of high biodiversity value. As we use globally available data as a starting point, this method is potentially applicable to other
world regions and provides a more environmentally relevant assessment of the land use impacts of agricultural products.
Keywords: biodiversity, land use, regional assessment, Kenya, spatial scales
1. Introduction
Agricultural production occupies about one third of the global terrestrial surface. This causes major
impacts on ecosystems and biodiversity at multiple spatial scales (e.g. local, regional and global). To
evaluate options for reducing these impacts, decision-support tools such as life cycle assessment (LCA)
should help decision-makers to obtain the relevant environmental information related to their product or
product system. In many life cycle impact assessment (LCIA) methods for land use, local impacts on
biodiversity are assessed (e.g. de Baan et al., 2012), which reflect the direct impacts on the used piece of land
(e.g. by removing forest-species to cultivate crops). These local impacts are traditionally assessed as
potentially disappeared fraction of species (PDF), representing relative changes in species richness between
a used piece of land and a reference situation (e.g. undisturbed natural vegetation). However, these local
assessment methods do not provide the information relevant for decisions-makers concerned about
conservation of species at larger scales, i.e. the absolute loss of species in a region or globally. Local
extirpation of species from a used piece of land can be fully reversible if the species can survive in adjacent
wild areas, and thus recolonize the field after its abandonment. As local conversion of habitat continues,
extinction risk increases to an extent that there is not enough habitat remaining at a regional or global level,
leading to regional or global extinction, respectively. Global extinction is fully irreversible and thus of
highest environmental concern. An assessment that incorporates both local and regional factors requires
additional information on the landscape surrounding the agricultural field, and is thus more data demanding.
In this paper, we present a method to upscale impacts from local to regional scale and to transform
relative into absolute species losses. We apply the method in a preliminary case study of agricultural
production and mammal species diversity in Kenya, using globally available data.
1.1. The case: agricultural production in Kenya
Previous land use LCIA methods have been mostly developed for the European (e.g. De Schryver et al.,
2010; Koellner and Scholz 2008) or North American context (e.g. Geyer et al., 2010), and to our knowledge,
only one study has focused on the African continent (Burke et al., 2008). We chose Kenya as a case study to
assess regional impacts on biodiversity because it harbours biodiverse areas at threat from human encroachment.
Kenya hosts two global biodiversity hotspots that have already lost more than 70% of their natural
habitats due to human activities. This largely results from an overlap in agricultural suitability and biological
value, which are both concentrated in South-Central and Western Kenya, and have attracted a dense and
growing population causing continued land use change or intensification and encroachment of protected
areas. Large shares of species rich ecosystems have been converted to small-holder and large-scale agricultural
land to produce subsistence or export-orientated cash crops such as tea, coffee, cashews, and flowers. A
strong dependence of the often poor rural populations on ecosystems for food, fuel and grazing land, coupled
with increasing population densities puts further pressures on ecosystems (Biggs et al., 2004). A more recent
threat to biodiversity comes from an increase in land excisions and sales to foreign investors for the purpose
of large-scale, export-oriented farming for food and biofuels production (Odhiambo 2011).
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