BIOENERGY FOR EUROPE: WHICH ONES FIT BEST?

4.2 European results: biofuels compared to fossil fuels 61
4.2.10 Results on biodiversity and soil quality
As discussed in the Chapter 3.4.1, four parameters were chosen to describe biodiversity and soil quality:
a) Soil compaction
b) Ecosystem occupation as an indicator of loss of biodiversity
c) Ecosystem occupation as a measure for life support functions of the soil
d) Harmful rainfall as an indicator of erosion
Of these, only the latter two yielded quantitative results, while for the other two parameters no calculations
could be carried out. Furthermore, even the results for the two parameters that could be calculated
were not included in the graphs of the previous sections. This is first of all due to their poor data reliability,
which is a result of yet insufficiently developed assessment methodologies and secondly, because
the two selected parameters do not describe biodiversity and land use issues sufficiently. However,
certain results have been obtained nonetheless which will be discussed in the following sections.
These results should be interpreted with care and not be used as a scientific decision base regarding the
biofuels in question. Bearing these limitations in mind however, they may be regarded as a first indication
of the nature of the results obtainable by means of more advanced assessment methods in the future.
Results on ecosystem occupation as a measure for life support functions of the soil
As explained in Chapter 3.4.1, ecosystem occupation is defined in terms of various parameters such as
yield, area, growing period and others. While most of these could be assessed fairly easily (see Annex
7.5 for further information), the values for the so called free net primary production were difficult to
assess for a number of crops due to a lack of data for aboveground production, root production and corresponding
decomposition rates. In many cases only a mean value could be given, while in other cases
values are estimates rather than hard figures. Hence the results should be interpreted with care. Because
of the poor overall data quality no sensitivity analysis was made. As the examples show free net primary
production values and yield data for the same crop differ between countries.
Examples for free net primary production in t/(ha*a) are:
Triticale: -4,0 (France) to 7,1 (Denmark)
Wheat straw: 4,9 (Germany) to 8,6 (Austria)
Sugar beet: -7,0 (The Netherlands) to 10,4 (France)
Examples for yield in t/(ha*a) are:
Rape seed : 2,7 (Austria) to 6,4 (Germany)
Miscanthus: 7,5 (Denmark) to 16,8 (Netherlands)
These differences indicate a level of uncertainty which prohibits a meaningful interpretation. They may
partly be due to differences in management practices between regions and countries, e.g. different harvesting
methods. In addition, climate and soil differences may have a substantial influence. This issue
requires further investigation.
Regarding the overall parameter ecosystem occupation the results can be summarised as follows:
• The ranking of crops according to their result on ecosystem occupation differs between countries.
For instance, sugar beet has the highest ecosystem occupation in Germany, and the lowest in the
Netherlands. Similarly, triticale has the highest score in Denmark, whereas in France it has the lowest
value. These differences need to be explored further in order to understand them.
• In some countries, ecosystem occupation values for rape seed, triticale and wheat turn out to be
negative. This implies that these crops are – with regard to those regions – better in providing free
net primary production than the average one in mid-Europe. Maybe information on soil structure
could explain the differences – possibly in combination with the annual addition of organic matter.
• In some countries, rape seed is followed by a grass filler crop in the same year. Hence in comparison
with grass fallow used here as a reference crop, the figures for ecosystem occupation by rape seed
and grass filler crop would have to be summed up if they were available.