Biodiversity

Biodiversity is reflected on various levels, encompassing the diversity within species (genetic diversity), the diversity between species, and the diversity of ecosystems. A high degree of biodiversity ensures the proper functioning of ecosystems, including agricultural systems, and is important as a gene pool for agricultural breeding or active pharmaceutical ingredients. In Switzerland, agricultural activities have a major impact on biodiversity, which they can both support and reduce.

Within the SAEDN, an indicator is calculated that describes the potential effects of agricultural practice on biodiversity. Based on Jeanneret et al. (2014), the method can be applied to grassland, arable land and semi-natural habitats (e.g. wildflower strips, hedgerows). The following groups of indicator species are taken into consideration:

• Grassland flora
• Arable companion flora
• Birds
• Small mammals
• Amphibians
• Molluscs
• Spiders
• Ground beetles
• Butterflies
• Wild bees
• Grasshoppers

Calculating the Biodiversity Evaluation

Based on several hundred studies, Agroscope has estimated the impact of agricultural activities (e.g. number of cuts, application of various plant protection products, the presence of ecological structural elements such as stone walls) on these indicator-species groups. This impact is represented by the variable R, where R lies between 1 (activity has a clearly harmful impact on biodiversity) and 5 (activity promotes biodiversity). The score of the option N_opt is then calculated with the following formula for each indicator-species group:

N_opt=R*(C_Management+C_Habitat)/2 

In general, the larger N_opt, the higher the potential for biodiversity. C_management lies between 0 and 10, and quantifies the importance of the activity for each indicator-species group. C_Habitat also adopts values between 0 and 10, and takes into account the importance of habitat for each indicator-species group. The final score for an indicator-species group and for a particular crop or grassland (N_fin) is then calculated by averaging N_opt over all management measures. For amphibians, molluscs, spiders, ground beetles, butterflies and grasshoppers, N_fin is additionally calculated for species which are only found in a few selected biotopes (e.g. Red List species). A total of 17 indicators are calculated in this way for various indicator-species groups.

Next, the various N_fin are summarised into an overall biodiversity evaluation (BD points), with each N_fin being weighted. The more important an indicator-species group is as a feed basis for other species and the more species-rich the indicator-species group is in agricultural areas, the higher its weighting. BD points can then also be calculated on the entire-farm level instead of just per crop or grassland. Here, it is assumed that the impact of the respective BD points is proportional to the area.

The following example for butterflies on permanent grassland is intended to illustrate the method: A high number of cuts (intensive use) leads to a low R (R=1), since this has a negative effect on butterfly diversity. In addition, this low R is heavily weighted, since C_Habitat and C_Management are relatively large: permanent grasslands are an important habitat for butterflies (C_Habitat=7); moreover, the number of grass cuts has a major impact on butterflies (C_Management=7) compared to other management options. Butterflies are fairly important in the food chain, and exhibit high overall species richness. For this reason, the low R owing to the number of cuts also has a relatively strong effect on the calculation of the BD points.

Contact

Publication

An expert system for integrating biodiversity into agricultural life-cycle assessment.

Jeanneret P., Baumgartner D. U., Freiermuth Knuchel R., Koch B., Gaillard G.
Ecological Indicators, 46, 2014, 224-231.