Vincent de Leijster

39 Agroecological management improves ecosystem services in almond orchards within one year 3 Above-ground biomass and carbon content Additionally, eight sub-plots of 25 x 25 cm were randomly distributed within each treatment plot. All the above-ground vegetation in these plots was cut manually and taken to the laboratory, where it was oven-dried at 60 °C and then weighed, to obtain dry biomass. The carbon content was calculated by multiplying dry biomass by the carbon fraction of 0.47 (IPCC, 2006). 3.2.3.3 Almond tree properties Almond nut biomass We measured almond production in farms 1, 3 and 4, and in one of the two parcels of farm 5 (the other parcel in farm5was -bymistake- harvested by the farmer before themeasurements had been done). In farm 2 the production was measured by the farmer herself following our protocol. The production was measured during the harvest season in August–September 2017. Trees were harvested in groups of at least four, and this was repeated 3-4 times per plot. The harvest was hulled and bagged per group, and then weighed to obtain the in-shell fruit production per tree. Additionally, one sub-sample of 20 fruits was taken from each bag and brought to the lab, where they were air dried. There, each sub-sample was weighed and shelled them and then weighed the kernels to calculate in-shell:kernel ratios and kernel average weight. Finally, we obtained two variables; first, the production indicator of almond yield per tree, which was expressed as kernel weight per tree, and second, the almond fruit quality indicator of kernel weight in grams per individual kernel. No sub-samples of the fruits were obtained from farm 2 and neither from one of the parcels in farm 5. Almond leaf nutrients In August and September 2017 three almond leaf samples were taken from four trees in each plot. The samples were oven-dried at 60 °C for two days. Leaf nitrogen content was measured by the Dumas method (Simonne et al., 1994). Leaf phosphorus and potassium contents were determined by the digestion method with 1:4 of H 2 O 2 30%: HNO 3 65%, and then analyzed with an inductively coupled plasma - optical emission spectrometer (ICP-OES). Fruit set ratio In February and March 2017 four trees were marked, each with four branches with minimum length of 0.5 m. On each of these branches all flowers were counted. In April and May 2017 we counted the fruits on these same branches. Fruit set was expressed as the number of fruits divided by the number of flowers (Klein et al., 2012).