Quantity and Quality of Semi-Natural Elements within the Swiss Lowland Farmland

In the Swiss lowland, the quantity of biodiversity promoting areas (BPA, i.e. options of the Swiss agri-environment scheme) clearly exeeds the stipulated 7%. The quality of the BPA has been improved as well. However, three forth of the BPA are still barely recognizable as semi-natural areas in the field.

The loss of biodiversity has been particularly strong on farmland. The Swiss Federal Office for Agriculture FOAG tries to counteract this development by means of a direct payment system which renders subsidy payments for the implementation, management, quality and connectivity of a defined set of agri-environment scheme options (biodiversity promoting areas, BPA). This study analyses how many semi-natural elements are present on a representative sample of 133 farms in the Central Swiss lowland (total surface 32,2 km2) and to which type of habitat they can be attributed. The amount of semi-natural habitats observed in the field sums up to 3.86% (6.36% when trees are included) which is still clearly below the target value as defined by the Environmental Objectives for the Agricultural Sector (EOAS). 75% of the BPA areas do not reach the relatively simple criteria for semi-natural habitats in our habitat mapping.

Although many farmers might still consider biodiversity enhancement as secondary on their farms, it would be wrong to hold only them responsible for the modest amount of semi-natural habitats in the landscape because:

• On 49 farms which were mapped in 2009 and in 2015, the surface of semi-natural habitats increased by 59% within just a few years. The number of standard trees also increased considerably. This effect is most probably caused by a biodiversity advisory service on counselled farms. However, also on non-counselled farms, there were more semi-natural habitats at the time of the second mapping.
• Some site-specific and/or economic conditions limit the possibility to promote biodiversity, particularly nutrient excess in certain regions of the Swiss lowland. This is manifested e.g. in a very small percentage of mesophilic and nutrient-poor shrub/hedge strips (< 1%).
• With the current scheme payment system, farmers are not always motivated to implement the most site-adapted BPA type. Often, the BPA type which generates the highest payments is not the BPA type which would yield the highest benefits for biodiversity.
• Nowadays, ecology is an issue during agricultural training, but the time allocated to this topic is very modest. The lack of BPA on arable land, for instance, must be at least partly attributed to this deficit.