Ecological and evolutionary effects of crop diversity decrease yield variability

Abstract

Abstract Higher plant species diversity decreases variability of plant community productivity. The stabilizing effect of plant diversity can result from species‐specific responses to environmental fluctuations and from shifts in competitive hierarchies. Evolutionary adaptation of species to surrounding plant diversity could further decrease productivity variability. We used a three‐year dataset from a crop diversity experiment with seven species to assess the effect of crop diversity and selection history on temporal variability of yield. We found contrasting patterns of temporal variability: Yield of species varied more in mixtures than in monocultures over years. However, at community‐level, we found lower yield variability in crop mixtures compared to monocultures, although only in combination with fertilizer application under Mediterranean climate. Furthermore, we found that a mixture selection history can increase yield productivity and decrease its variability, although only in monocultures. This suggests that the interspecific interactions among crops in mixtures act as an evolutionary selective force, promoting niche complementarity. Synthesis. Our results highlight the ecological and evolutionary role of plant interactions in crop mixtures, which can affect yield stability, while also reflecting on the importance of climate and resource availability in modifying the diversity‐stability relationship.