The relative importance of geophysical constraints, amenity values, and farm-related factors in the dynamics of grassland set-aside

This study aimed at quantifying the spatial distribution of set-aside – highly valuable biodiversity reservoirs – in a typical lowland agricultural region (Denmark), just before and after the set-aside policy change (years 2007 and 2008), to assess which factors drive farmers’ set-aside priorities, and to elaborate the potential consequence of the set-aside spatial transformation from 2007 to 2008 on nature.

Multiple regressions were used to test if and how set-aside is linked to three potential groups of drivers: (1) geophysical constraints (topographic and edaphic constraints on the farming-suitability of an area), (2) amenity values (nature conservation and aesthetic values), and (3) farming-related factors (e.g., field size and livestock density).The spatial distribution of set-aside was influenced by both geophysical constraints and amenity values and only some extent farming-related factors.

More specifically, set-aside was predominantly located in areas with steep slopes, high wetness and to a lesser extent low soil fertility, a large nature area, and low livestock densities, though not as pronounced in 2008 as in 2007. These were also the areas with the strongest loss in set-aside area from 2007 to 2008, though these relationships were rather weak, thereby indicating a strongest set-aside loss in areas where set-aside would potentially benefit nature the most.

The importance of the different drivers showed strong geographical variation, perhaps reflecting local differences in interacting factors such as farmers’ cultural values or socioeconomic circumstances. Overall, it is clear that the distribution and dynamics in grassland set-aside is determined by a complex interplay of agronomic and non-agronomic factors, with geophysical landscape factors as well as amenity values playing important roles.