Vincent de Leijster

53 Agroecological management improves ecosystem services in almond orchards within one year 3 wasps and ants combined represent 17% of the flower visits, while bees and flies combined represent 76.6% (Ortiz-Sánchez and Tinaut, 1993). Finally, the population dynamics of farm arthropods largely depend on processes that occur at a scale larger than an agricultural plot (Silva et al., 2010), and our relatively small plots may have been ineffective in measuring these larger-scale dynamics. . Food provisioning During our study, the region experienced an exceptionally cold spring, which damaged almond blossom (personal observation) and affected yield. The trees on the farms in our study also suffered frost damage, causing low and variable production. The average minimum daily temperature in March from the weather stations nearby the farms was 27% lower in 2017 compared to the average from 2000-2016 (AEMET; Appendix Figure A3-1). Moreover, another study in southern Spain reported almond yields of 1-3 kg in kernel weight per tree, which is remarkably higher than what we found (Almagro et al., 2016; De Giorgio and Lamascese, 2005). The low spring temperatures may explain our results that almond yield and kernel weight did not differ significantly between CT and the other treatments. Previous studies on almond orchards reported a lower crop yield in NT than in CT (De Giorgio and Lamascese, 2005; Martínez-Mena et al., 2013). A 20-year-long study on tillage versus no tillage management in corn fields in the United States found that no tillage had an almost immediate positive effect on soil properties but its effect on crop yield lagged behind, with crop yields not outweighing those in tillage management until after 13 years (Ismail et al., 1994). To our knowledge, there are no comparable long-term studies in Mediterranean woody-crop systems and therefore it is unwise to extrapolate to our case. Moreover, we did not find any effect of GM or CM on almond yield. For GM our results agree with those found for almonds in Italy, where no significant difference in production was found between GM and CM (De Giorgio and Lamascese, 2005), but not with those in Spain, where production in GM was reported as 41% higher than in CT (Almagro et al., 2016). Nonetheless, we did find a significantly higher kernel nut weight for CM, which relates to a higher price for almonds. Although the combined effect of understory cover and soil amendment has not yet been investigated for almonds, it has been investigated for apricots, where combining understory cover and compost can increase crop yield by 28% within four years (Montanaro et al., 2010). Ecosystem service bundles and trade-offs The results from the PCA show a negative correlation between understory cover and crop yield for the first two axes (Figure 3-3). Nevertheless, due to the climatic conditions during our study, crop yields were lower than average and therefore no conclusions on trade-