There is increasing evidence that species can evolve rapidly in response to environmental change. However, although land use is one of the key drivers of current environmental change, studies of its evolutionary consequences are still fairly scarce, in particular studies that examine land-use effects across large numbers of populations, and discriminate between different aspects of land use. Here, we investigated genetic differentiation in relation to land use in the annual grass Bromus hordeaceus. A common garden study with offspring from 51 populations from three regions and a broad range of land-use types and intensities showed that there was indeed systematic population differentiation of ecologically important plant traits in relation to land use, in particular due to increasing mowing and grazing intensities. We also found strong land-use-related genetic differentiation in plant phenology, where the onset of flowering consistently shifted away from the typical time of management. In addition, increased grazing intensity significantly increased the genetic variability within populations. Our study suggests that land use can cause considerable genetic differentiation among plant populations, and that the timing of land use may select for phenological escape strategies, particularly in monocarpic plant species.

Summary Land‐use change is an important component of global environmental change and a major driver of current declines in biodiversity. Although there is increasing evidence that species can evolve rapidly in response to anthropogenic environmental change, comprehensive studies of the evolutionary consequences of land use are still fairly scarce, in particular such that consider multiple species, study many populations, or that discriminate between different aspects of land use. Here, we studied genetic change of key phenotypic traits in response to land use in eight common grassland species across 137 grassland sites covering a broad range of land‐use types (mowing and/or grazing, with or without fertilization) and intensities in three regions of Germany. A common garden study revealed significant genetic differentiation in response to land‐use intensification within all of the investigated species. Among the studied land‐use processes, mowing appeared to have the strongest effect on the differentiation of plant phenotypes, with flowering phenology as the most responsive trait. However, there was substantial variation among species in the magnitude, sometimes also the direction of the observed population differentiation. Synthesis. Our study demonstrates that evolutionary responses of grassland plants to land‐use change are a common phenomenon and widespread across a broad range of different species. These evolutionary changes are likely to impact biotic interactions, as well as the structure and functioning of communities and ecosystems.

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