Intercropping generates trait plasticity, which corresponds with year‐to‐year stability in productivity

Abstract Environmentally friendly approaches to increasing food production include using the positive effects of plant biodiversity, such as in intercropping. Functional traits are key drivers of these positive effects, in part because variation in functional traits can increase niche partitioning. However, we know little about how variation in functional traits affects the long‐term stability of yield in agroecosystems. We conducted a 5‐year field experiment with five different cropping systems; maize/peanut, maize/soybean intercropping, and maize, peanut and soybean monocultures. We compared the productivity of monocultures to intercrops and then compared plasticity in functional traits at different rates of nitrogen supply between the cropping systems. Intercropping generated plasticity, measured here as the inverse of the coefficient of variation, in three functional traits of maize (height, stem diameter and ear height), which probably increases above‐ground spatial niche differentiation, and decreases the intraspecific competition of maize. Intercropping also increased the stability of grain yield and above‐ground biomass. Plasticity in functional traits of maize correlated positively with year‐to‐year temporal stability (CV −1 ) of grain yield and biomass of maize and with the total productivity of the agroecosystem. Synthesis and applications. Our study provides evidence of the greater productivity and temporal stability of species‐diverse intercropping systems. Interspecific interaction‐induced plasticity suggests a unique mechanism for biodiversity effects on ecosystem function, which adds to our understanding of fixed, or inherent, variation in traits among genotypes or species. Theoretically, our findings provide novel insights into how interspecific interactions contribute to ecosystem service, especially in yield temporal stability, by increased trait plasticity of the dominant crop, maize. The results also had implications for applying intercropping in the sustainable management of food‐production systems with the use of more crop species. Greater stability in production has the potential to provide a stable income for farmers.