… and what about the farm scale?

Landscape ecologists are familiar with the issue of scale. In rural landscapes, they often claim to work on a range of scales: “From plot to farm to landscape”, for example. Yet, the farm scale poses various problems because it actually relates to an economic unit (the farm business) rather than to a spatially coherent piece of land. Often the plots of an individual farm are interspersed with other land uses and/or with plots managed by other farmers. This makes it challenging to relate biodiversity indicators to the farm scale.

At the same time, farmers are the most important decision makers. They decide on the farm type (e.g. arable or livestock or mixed), on the farming system (e.g. conventional or organic) and on the business model (label production, direct marketing, mass production, agri-environmental scheme, etc.). They are in charge of mid-term planning (e.g. crop rotation, livestock breeding strategy) and of the day to day management of the farm (timing of field operations, plant protection measures, etc.). Also, they obtain subsidies for agri-environmental schemes and for the implementation of ecological focus areas. Those decisions directly affect the fate of wildlife on their farms. Therefore, there is a need for biodiversity indicators at the farm scale, despite the above mentioned methodological difficulties.

Key questions in this context are:
- What is a farm? Which habitats are part of the farm and which are not?
- How can farms be mapped in a consistent and reproducible way?
- Is there a minimum set of farm habitat descriptors?
- How can semi-natural farm habitats be distinguished from intensively managed farmland?
- How do farm habitat descriptors relate to species diversity descriptors?

In order to develop and test a generic approach, we mapped 195 farms across 12 European countries. Based on those findings, we propose a core set consisting of (i) four descriptors to measure structural composition and configuration of farms (Habitat Richness, Habitat Diversity, Patch Size, and Linear Habitats), (ii) three descriptors addressing specific habitat types (Crop Richness, Shrub Habitats, and Tree Habitats) and (iii) one interpreted descriptor (Semi-Natural Habitats). As a set, the descriptors make it possible to evaluate the habitat status of a farm and to track changes occurring due to modified land use and/or management, including agri-environmental measures.