Vincent de Leijster

211 Summary of farms applying agroecological practices. The case studies differ in the specific practices that are implemented and the timescale on which ecological and economic impacts are evaluated. In Chapter 3 , I present the results of examining the short-term effect of agroecological interventions in almond orchards on ecosystem service supply. To this purpose, the agroecological practices ‘no tillagewith spontaneous vegetation’, ‘greenmanure’, and ‘compost’ were experimentally implemented in five almond plantations. Together with my co-authors, I evaluated whether after one year the ecosystem services on these sites differed from those of conventional tillage management, which was the mainstream practice in the region. We found that the accumulated ecosystem service supply was 17- 28% higher on the agroecological sites than on the conventional tillage sites. However, each practice supported a different set of ecosystem services. Vegetation cover under ‘no tillage’ and ‘green manure’ improved understory carbon content, plant species richness and soil microbial activity, which are indicators of the ecosystem services ‘carbon storage’, ‘habitat provisioning’ and ‘nutrient cycling’. Compost application supported soil-related ecosystem service indicators such as ‘soil microbial activity’, ‘soil and tree nutrient content’ and ‘soil carbon storage’. Moreover, compost also improved the provisioning services as indicated by heavier almond kernels. Insect-mediated ecosystem services, ‘pest control’ and ‘pollination’, were not affected by the agroecological treatments, but we concluded that changes may develop over longer timescales or larger spatial scales. Although we found no significant effect of treatments on almond production, we did find a trade-off between vegetation cover and almond production (Figure 3-3). A combination of practices, such as vegetation cover with organic amendments, may prevent such trade-offs, but this needs further research. To conclude, ecosystem services may improve rather rapidly after agroecological interventions; however, each practice may enhance a specific set of ecosystem services, so it may be expected that combining them leads to improved ecosystem services. My co-authors and I followed up on these findings in Chapter 4 , where the economic implications of agroecological management in Spanish almond orchards are examined. More specifically, we modeled the development of Net Present Value (NPV; economic performance) of the same agroecological interventions as in Chapter 3, based on empirical data on almond production obtained from the experiments in Chapter 3 and data on costs and benefits derived from farmer surveys. We found that all practices resulted in profitable outcomes; however, compost was most profitable, followed by conventional tillage, then green manure and least profitable was no tillage. This could be explained by the almond production, because we found that the production in no tillage and green manure plots was lower when using conventional tillage, resulting in lower NPVs. Nevertheless,