Facilitation and biodiversity–ecosystem function relationships in crop production systems and their role in sustainable farming

Abstract

We review the need for increasing agricultural sustainability, how this can in part be delivered by positive biodiversity–ecosystem function (BEF) effects, the role within these of plant–plant facilitation, and how a better understanding of this role may help to deliver sustainable crop (particularly arable) production systems. Major challenges facing intensive arable production include overall declines in biodiversity, poor soil structure and health, nutrient and soil particle run‐off, high greenhouse gas emissions, and increasing costs of synthetic inputs including herbicides, pesticides and fertilisers. Biodiversity–ecosystem function effects have the potential to deliver win–wins for arable food production, whereby enhanced biodiversity is associated with ‘good outcomes’ for farming sustainability, albeit sometimes through negative BEF effects for some components of the system. Although it can be difficult to separate explicitly from niche differentiation, evidence indicates facilitation can be a key component of these BEF effects. Explicit recognition of facilitation's role brings benefits to developing sustainable crop systems. First, it allows us to link fundamental ecological studies on the evolution of facilitation to the selection of traits that can enhance functioning in crop mixtures. Second, it provides us with analytical frameworks which can be used to bring structure and testable hypotheses to data derived from multiple (often independent) crop trials. Before concrete guidance can be provided to the agricultural sector as to how facilitation might be enhanced in crop systems, challenges exist with respect to quantifying facilitation, understanding the traits that maximise facilitation and integrating these traits into breeding programmes, components of an approach we suggest could be termed ‘Functional Ecological Selection’. Synthesis. Ultimately, better integration between ecologists and crop scientists will be essential in harnessing the benefits of ecological knowledge for developing more sustainable agriculture. We need to focus on understanding the mechanistic basis of strong facilitative interactions in crop systems and using this information to select and breed for improved combinations of genotypes and species as part of the Functional Ecological Selection approach.

Combining Genetic Gain and Diversity in Plant Breeding: Heritability of Root Selection in Wheat Populations

“…Shade avoidance can be maladaptive in wheat monocultures in terms of population yield [51] but adaptive in terms of community yield if the cropping system is diversified and plasticity aids optimal niche complementarity, e.g., in grassland species mixtures [52]. Hypothetically, this could hold true for crop species mixtures [53]. Consequently, genotypes such as Sel_L56 that might have increased shade avoidance and show high absolute early vigor in SL, SRL, leaf, and plant length might be promising in diversified cropping systems.…”

Talking with Strangers: Improving Serianthes Transplant Quality with Interspecific Companions

“…But, our results also illuminate elaborate root communication that forms adversarial or beneficial relationships with many other organisms in the pedosphere, and these relationships are crucial for sustaining health of the individuals and organizing communities; as well as the ecosystem as a whole [10,13,14,[32][33][34]. Our study adds to the burgeoning body of evidence illustrating how knowledge of the hidden half can be exploited to improve plant growth and productivity in managed production systems e.g., [6].…”

“…For example, Li et al [5] found that root exudates from Zea mays L. promoted Vicia faba L. nodulation and increased N 2 -fixation to increase Z. mays productivity when the two species were intercropped. Such biodiversity effects in modern cropping systems are supported by ancient origins and contemporary ecological research [6]. Other experimental and observational studies have advanced our understanding of how such root behavior contributes to the over-yielding that often accompanies biodiversity [4,[7][8][9][10][11].…”

Breeding Beyond Monoculture: Putting the “Intercrop” Into Crops

“…While a single wheat genotype can be selected to poorly compete with its conspecifics in a monoculture stand, it is less clear what sort of interactions should be selected for among intercrop partners, particularly given the dynamic and inter-dependent nature of these interactions. An increasingly detailed description of favorable interaction effects is being compiled, although it remains context-, crop-, and experiment-specific in many cases ( Brooker et al, 2021 ). Efforts to generate in silico ideotypes are providing novel insights ( Louarn et al, 2020 ), but still require confirmation of their ability to predict as-yet unidentified traits with significant agronomic impact.…”