Plant cultivation in agriculture is directly linked to the use of land. Existing arable land and grassland can be used, or semi-natural land can be converted to arable land or grassland. The agricultural land footprint (aLF) quantifies which arable and grassland areas in Germany and abroad are used for the production or consumption of agricultural goods in Germany and how large the associated land conversions are.
Crop cultivation is one of the most important land uses worldwide and is responsible for the conversion of semi-natural land. In addition, Germany occupies large shares of land in other countries through its biomass imports. This land use and especially land conversion poses a risk to ecosystem services and biodiversity. The development of the agricultural land footprint makes it possible to assess the impact of the German bio-economy on these risks as a sum parameter.
The calculation of the agricultural land footprint is based on the results of an integrated modelling approach:
- A material flow model (based on the multi-regional input/output database EXIOBASE) determines for 49 regions worldwide (44 individual countries and 5 aggregated "rest" regions) the share of production of different crop classes grown directly or indirectly for consumption in Germany. The agricultural land footprint is also calculated for exported agricultural goods and products.
- A spatially explicit land use model (LandSHIFT) models the global distribution of cultivation for the same crop classes and calculates land occupation. Assumptions about yield changes in each region are incorporated here. The land use for the field crops is calculated on the basis of EXIOBASE product groups.
- For the area occupation it is analysed in 5 year steps, which previous use existed. Thus, conversion of primary forest, biodiverse forest, biodiverse grassland, other biodiverse land, peatland, wetland, forest, unused grassland, and used grassland to cropland is assumed to be associated with increased risk to ecosystem services and biodiversity (risk areas). For areas "in use" such as used cropland (including fallow) and settlement land, this risk is estimated to be significantly lower. For new grassland use, grassland already in use is generally assumed to be "in use". Land conversion in protected areas is excluded from the calculations.
- The allocation of risk areas in the country of origin takes into account changes in imports to Germany and changes in production in the country of origin (e.g., yield increases). For example, if imports to Germany do not increase or increase only to the extent of the increase in production in the country of origin, only area in the "in use" category is allocated to imports to Germany and no area conversion. Import increases beyond this are assigned to conversion of at-risk land.
- Based on the land use, an annual land conversion rate is calculated for the risk areas per category of risk areas and related to the inhabitants in Germany.