The roles of non‐production vegetation in agroecosystems: A research framework for filling process knowledge gaps in a social‐ecological context

Abstract An ever‐expanding human population, climatic changes and the spread of intensive farming practices are putting increasing pressure on agroecosystems and their inherent biodiversity. Non‐production vegetation elements, such as woody patches, riparian margins and restoration plantings, are vital for conserving agroecosystem biodiversity. Furthermore, such elements are key building blocks that are manipulated via land management, thereby influencing the biotic and abiotic processes that underpin functioning agroecosystems. Despite this critical role, there has been a lack of synthesis on which types of vegetation elements drive and/or support ecological processes, and the mechanisms by which this occurs. Using a systematic, quantitative literature review of 342 articles, we asked the following questions: what are the effects of non‐production vegetation on agroecosystem processes and how are these processes measured within global agroecosystems? Woody patches, hedgerows and borders, riparian margins, and shelterbelts were the most studied types of non‐production vegetation. The majority (61%) of studies showed positive effects of non‐production vegetation on ecological processes, where the presence, level or rate of the studied process was increased or enhanced. However, four key research gaps were revealed: (a) most studies (83%) used proxies for, instead of direct measurements of, ecosystem processes related to non‐production vegetation; (b) study designs used to investigate non‐production vegetation effects on ecosystem processes directly were largely limited to observational comparisons of non‐production vegetation types, farm‐scale vegetation configurations and different proximities to vegetation in terms of the effect on ecological processes; relatively few studies used manipulative experiments; (c) the relatively few studies directly measuring ecosystem processes were dominated by four process categories: invertebrate biocontrol, predator and natural enemy spillover, animal movement, and ecosystem cycling and (d) the methods used to directly measure non‐production vegetation effects comprised a surprisingly limited set of approaches. To fill key research gaps that will inform the use of non‐production vegetation to enhance agroecosystem processes, we present a framework for future research that emphasizes the need to combine an understanding of human decision‐making with carefully designed and targeted investigations into the roles of taxa, ecosystem processes, and landscape heterogeneity related to non‐production vegetation, at multiple spatial scales within agroecosystems.