Anna Kirschbaum, Oliver Bossdorf, J F Scheepens

Aims
Plant populations in managed grasslands are subject to strong selection exerted by grazing, mowing and fertilization. Many previous studies showed that this can cause evolutionary changes in mean trait values, but little is known about the evolution of adaptive plant phenotypic plasticity in response to grassland management.
Methods
We conducted an outdoor common garden experiment to test if plants from more intensively mown and grazed sites showed an increased ability to regrow after biomass removal. We worked with three common plant species from temperate European grasslands, with seed material from 58 – 68 populations along gradients of land-use intensity, ranging from extensive (only light grazing) to very intensive use (up to four cuts per year).
Important findings
In two species, we found strong population-level variation in regrowth ability of fitness-related traits in response to a clipping treatment, which could reflect adaptation to land-use intensity. While the regrowth ability was unrelated to the land-use intensity of populations of origin, we found a relationship with the predictability of grassland management in P. lanceolata where plants experiencing more stable environmental conditions over the last 11 years showed stronger regrowth in reproductive biomass after clipping. In summary, grazing and mowing intensity apparently did not select for regrowth ability, but in some species, predictable heterogeneous environmental conditions created by land use may have caused its evolution.