Vincent de Leijster

134 Chapter 6 co-products were approximately 30% of what they could potentially be (€800 ha -1 y -1 ; Figure 6-3). If more of these products are brought to market, agroforestry is expected to be more profitable than monoculture coffee. A decrease in net revenue on the short-term (1-10 y) and an increase on the long- term (>10 y) after trees had matured could have been expected, because a canopy with excessive shade would negatively affect coffee yield (Tscharntke et al., 2011) and income from tree products would only be generated on the long term (Stroesser et al., 2018). Nevertheless, the results herein were against this expectation as the development of the canopy layer resulted in a decrease in coffee yields (appendix Figure A6-2); however, it did not translate into a negative effect on the gross revenues (Figure 6-1), while additional income from timber and fruit was obtained (Figure 6-3). A shade experiment in Costa Rican coffee plantations showed similar results for coffee yield; after planting Inga trees, coffee yield decreased compared to monocultures, especially in the years with little pruning (Siles et al., 2010). Nonetheless, the same Costa Rican study also showed that coffee bean quality improved as the trees matured (Siles et al., 2010). Here, we found the opposite, that coffee bean (and also plantain) quality decreased over time (appendix Figure A6-2). This was unexpected, as our previous results on measured physical parameters of coffee beans in the field showed improved quality (De Leijster et al. 2021). This could be explained because shade is not the only factor contributing to coffee bean quality (Muschler, 2001; Siles et al., 2010; Vaast et al., 2006b); some studies showed that climate (Jaramillo et al., 2011), altitude and soil (Skovmand Bosselman et al., 2009), and post-harvest processing (Hameed et al., 2018) played a more important role. In our case it is likely that altitude plays a role as more mature agroforestry farms occured on lower altitudes (appendix Figure A6-3), which could also be associated with higher temperatures, which negatively affect coffee bean quality (Hameed et al., 2018). Despite the growing actual gross revenues of tree-products (fruits and timber) over time (Table 6-3 and Appendix Figure A6-4), their contribution to total gross revenues was low, representing less than 2% of the value of coffee gross revenues (Figure 6-3). Management costs were barely affected by the transition to agroforestry (Table 6-3). We found a significant reduction in costs of harvesting, pruning and processing, but this can be explained by its dependency on coffee yield, since lower yields relate to less labour and costs for harvesting, processing and transporting. The management costs of trees and Musa plants were low, as they accounted for 5% of the total costs (Figure 6-3). Farmers in this region did not have initial starting costs for purchasing trees, as trees were supplied by the tree planting projects. The price for seeding trees was not known among farmers, because there were no nurseries in the region. Farmers either grew new trees themselves (mostly legume and native trees) or received them via projects administered by the National