Our agricultural systems, heavily based on monocultures, are facing important sustainability challenges. So there is a need to improve and expand the use of more sustainable practices. Polycultures are agricultural systems where two or more species are grown together. These systems have been shown to have multiple benefits over monocultures, stemming partly from the exploitation of functional diversity. There is indeed wide recognition of the importance of interspecific variation in promoting functional diversity in agroecosystems. However, the role played by intraspecific variation, in particular variability mediated by phenotypic plasticity, has been little discussed in the context of agroecosystems. We carried out a bibliographic review of the agronomic and agroecological literature to identify different plastic responses and their consequences on annual agroecosystems. Based on concepts and advances of community ecology we built a framework to characterize the diversity of ways in which plasticity modulates ecological dynamics and performance.
Results/Conclusions
Three possible ways in which plasticity can manifest in agroecosystems were identified. First, plasticity can manifest as a consequence of agroecological practices. Therefore, spatio-temporal arrangement, biotic interactions, abiotic conditions and management practices can trigger a wide diversity of plastic responses in cultivated plants. Second, plasticity can manifest as a cause by altering agro-ecological interactions: (i) in competition plasticity can promote or limit complementarity and selection effects depending on how it affects niche and/or hierarchy traits; (ii) in facilitation most plastic responses are species-specific and are fundamental in the facilitated species; (iii) in herbivory, plasticity and trait-mediated interactions between cultivated plants and associated biota are fundamental in biological control and to understand below and above-ground interactions. Third, plasticity also manifests itself in the modulation of other plastic responses. Thus, the ability to plastically respond to a first stimulus can be limited or enhanced by a second stimulus. The evidence integrated in this review highlights the important role of phenotypic plasticity in the functionality of agroecosystems and ecosystems and suggests that plasticity should be considered more systematically in the study and design of sustainable polycultures.
