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
The taxon sensitivity s is calculated as the relative decrease in species richness on a human modified
i
land compared to an undisturbed reference ref. Finally, the predicted number of species that might get regionally
extinct can be calculated as (Koh and Ghazoul 2010).
n
z
æ A ö
å p
i is i
new
Slost = Sorg - Sorg ç
è A
÷
Eq. 6
org ø
From the regionally extinct species, some species might not occur in any other world region (i.e. species
endemic to one ecoregion), and thus get globally extinct. This is considered a global land use impact and is
fully irreversible. We thus split the calculations into non-endemic and endemic species. The first are used to
calculate occupation and transformation impacts (which are considered to be reversible) and the latter are
used to calculate permanent impacts, which are considered to be irreversible. The total number of species
regionally extinct is equal to the number of endemic and non-endemic species lost.
We calculated the potential regionally or globally extinct mammal species using data from WWF ecoregions
(Olson et al., 2001) as spatial units. The area shares of different land use types were derived from the
Globcover land cover map v2.3 (ESA 2009). Values for z were derived from Drakare et al., (2006) and for
the taxon sensitivity σ we used data from de Baan et al., (2012).
2.2 Calculation of characterisation factors
Above, we used the matrix SAR to estimate the number of endemic and non-endemic species lost due to
all accumulated land use activities within one ecoregion. For application in LCA, the impact per land use
type and area is required. Therefore, the total regional impact had to be allocated to the different land use
activities occurring within the region, to get an estimate of the number of species lost due to a specific land
use type. In a first step, we divided the number of lost endemic and non-endemic species by the used area.
Then, we allocated the impacts per area to the different land use activities, whereby the land use activity with
the lowest habitat value and the largest area share got the highest share of the impacts.
Finally, we calculated characterisation factors for land occupation and transformation based on impacts
on non-endemic species (considered as reversible impacts, see Fig 1). Impacts on endemic species were used
to calculate permanent (irreversible) impacts.
The regional characterisation factor for occupation impacts were calculated by dividing the number of
lost non-endemic species by the total used area and multiplying it with the allocation factor.
Transformation impacts were then calculated by multiplying the CF of occupation with half the time required
for species to recolonize an area after the land was abandonment. As empirical data on regeneration
times are missing, we assumed a constant regeneration time of 150 years for artificial area and 100 years for
agricultural land.
Permanent impacts were calculated as the number of endemic species lost due to land use. These species
are not occurring in any other global ecosystem and are thus permanently extinct, if they cannot persist in the
ecoregion. In order for the three impacts (transformation, occupation and permanent) to be aggregated in a
final step, they must be in the same units, i.e. [species loss* area * time], see Fig 1. Thus, we assessed the
permanent impacts over a certain modelling period. Here we used a 500 years modelling period as suggested
by Koellner et al., (2012a).
For calculating occupation impacts of agricultural products, the characterisation factor for occupation is
multiplied by the land use inventory flow of land occupation, given as [area * time]. The transformation and
permanent impacts are multiplied by the inventory flow of land transformation, given as [area].
3. Results
We calculated the habitat loss in each Kenyan ecoregion due to the total current land occupation and past
transformation and modelled the potential loss of endemic and non-endemic mammals per ecoregion. The
degree of habitat conversion varied substantially across ecoregions, with very little use in desert ecosystems
and up to 85% converted land in agriculturally suitable areas (Fig 2). The total mammals species richness
varied between ecoregion from 27 to 221 with zero to 6 endemic mammals per ecoregion. For nonendemic
mammals, zero to 14 species were predicted to be regionally extinct due to all land use activities (Fig 3). For
endemic species, zero to 0.4 species per ecoregion were predicted at risk of global extinction due to past
habitat conversion (Fig 4).
A selection of the resulting regional characterisation factors for occupation, transformation and permanent
impacts is displayed in Table 1. Compared to local (relative) characterisation factors calculated by de Baan et
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