Soil texture involvement in wildflower strip ecosystem services delivery in Mediterranean agro-environment

Abstract

The biodiversity restoration of the agroecosystem through wildflower strips is one of the most important agronomic strategies of the last few decades. However, poor knowledge of the bio-agronomic characteristics of the various wildflower species often leads to suboptimal performances especially as a result of their poor seed germination and poor seedling emergence due to the erratic soil texture. A two-year experiment involving the sowing of eighteen wildflower species in different texture conditions highlighted how some species emerged earlier or more effectively than others and verifying the consequent ecosystem service provided to pollinators. Species with smaller seeds were more inhibited by sowing in soil with high content of clay. Additionally, an inverse relationship (Boltzmann's sigmoidal regression) was found between seed weight and soil-mediated inhibition. This soil-mediated inhibition was higher in the clayey textured soil, showing that this inhibition was mediated both by seed weight and by the clay particles of the soil. The reciprocal interference between the emerged seedlings also determined a further decline in the wildflower species with small seeds. This differing agronomic performance, after sowing in the two different soil textures, did not affect the number of pollinator visits. Performance differed both in terms of floristic biodiversity and pollinator biodiversity. Finally, the experiment highlighted the importance of the appropriate selection of the wildflower species for biodiversity restoration - not only in terms of pollen and nectar availability for pollinators, but also in terms of compatibility with the soil texture in which the wildflower seeds are sown.