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Duru et al. (Agron Sustain Dev 35:1259-1281, 2015) highlighted a missing tool for studying and improving the performance of cropping systems in the transition to highly diversified agriculture. In response, this paper proposes a concept for designing, modeling, monitoring, and auditing desired ecosystem services, in intercropping and agroforestry systems. We have labelled this concept ESSU (Ecosystem Services functional Spatial Unit). It delimits the smallest spatial unit encompassing all the interacting species and other functional components (e.g., crops, trees, livestock, spontaneous vegetation, semi-natural habitats such as hedges, ditches, forest patches, and animals) that together provide a specified set of ecosystem services. The novel ESSU concept allows representation of an entire diversified agroecosystem by the repetition of the spatial unit that provides the same sets of targeted ecosystem services as the agroecosystem it represents. It can then be used for various activities, such as the (i) design of more efficient agroecological systems according to the targeted ecosystem services; (ii) rapid audit of farming practices for biodiversity/resilience across large tracts of farmland as part of achieving Sustainable Development Goal 2 targets of sustainable food systems; and (iii) modeling such diversified agroecosystems using a motif adapted to represent the targeted ecosystem services and the species spacing design. We demonstrate that the ESSU concept is highly flexible and applicable to a wide range of diversified agroecosystems, like arable intercropping, crop-tree intercropping, tree-tree agroforestry, and agro-pastoralism. We also show its relevance and suitability for representing temporal changes over 1 year, across several years, and over decades, indicating its generalizability and flexibility. We argue that ESSU could open new theoretical and practical research avenues for the study of diversified agroecosystems. Considered with all the knowledge available on practices, biodiversity, and ecosystem services, ESSU might provide a learning-support tool to fill the knowledge gap about relationships among practices, biodiversity, and associated ecosystem services. [ABSTRACT FROM AUTHOR]

The rising demand for vegetable oil is inducing an expansion of oil palm cultivation in the tropics. In southern Cameroon oil palm smallholdings have been growing fast since the mid-1990s. Now, industrial plantations and smallholdings exist side by side. The current technical advice given to smallholders originates from agroindustrial practices. However, industrial plantations were created by planting on previous forest cover with no food intercrops, whereas for smallholdings food crops are a common previous cover and an intercrop during the juvenile phase. Technical advice used for industrial plantations may therefore not apply to smallholdings. Huge yield differences are observed in oil palm smallholdings, ranging from 2 to 14 t·ha of fresh fruit bunches, while in industrial plantations yields average 14-16 t·ha. As no agronomic evaluation to date had explained those variations, we carried out a regional agronomic diagnosis of N and K nutrition on smallholder plots planted with selected oil palms. To prepare leaf samples and determine mineral contents, we used the same standardised method and the same laboratory as the regional industrial plantations. We compared smallholder leaf N and K contents with reference models of critical mineral contents, previously built with data from the high-yielding industrial plantations. Statistical links were also established between nutritional status and practices. Our results showed two groups of oil palm plantations: a group with N deficiencies ranging between 80 and 90% of the reference and K deficiencies ranging from 45 to 90% of the reference, and another group with satisfactory N and K status. The N deficiency was statistically linked to food cropping as the previous cover or as an intercrop, whilst K deficiency was qualitatively linked to an absence of K fertilisation. N deficiency is a specificity of oil palm smallholdings that had never been encountered in African industrial plantations. To conclude, the current technical advice given to smallholders is not well adapted. [ABSTRACT FROM AUTHOR]