Vincent de Leijster

48 Chapter 3 3.3.2 PCA The first PCA axis was interpreted as inversely related to phosphatase activity, urease activity and soil N and SOC contents (Table 3-4). The second PCA axis was positively related to plant species richness, understory cover and understory carbon content, and negatively to soil K content and almond production. The third PCA axis was negatively related to glucosidase activity, leaf P content, almond productivity and pollinator abundance. The three axes to- Table 3-4. PCA scores for the indicators of ecosystem services. Ecosystem services Indicator PC1 PC2 PC3 Nutrient cycling Dehydrogenase activity -0.17 0.18 -0.15 Nutrient cycling Glucosidase activity -0.24 0.11 -0.54 Nutrient cycling Phosphatase activity -0.43 0.00 0.10 Nutrient cycling Urease activity -0.42 -0.12 0.19 Nutrient cycling Total soil N content -0.38 -0.23 -0.08 Nutrient cycling Soil extractable P content -0.15 -0.16 0.17 Nutrient cycling Soil extractable K content -0.21 -0.28 0.10 Nutrient cycling Leaf N content -0.16 0.09 -0.05 Nutrient cycling Leaf P content 0.02 -0.09 -0.38 Nutrient cycling Leaf K content 0.10 -0.13 -0.01 Carbon stock SOC -0.38 -0.20 -0.08 Carbon stock Understory carbon stock -0.04 0.27 -0.07 Habitat provisioning Arthropod abundance 0.09 0.04 0.16 Habitat provisioning Arthropod order richness 0.00 0.01 0.15 Habitat provisioning Plant species richness -0.22 0.54 -0.04 Habitat provisioning Understory cover -0.17 0.43 -0.13 Food provisioning Almond yield 0.12 -0.27 -0.49 Food provisioning Kernel weight -0.15 -0.21 -0.03 Pest control Pest absence -0.15 -0.01 0.30 Pollination Fruit set 0.09 -0.21 -0.18 Pollination Pollinator abundance 0.14 -0.01 0.29 SD 0.55 0.43 0.32 Proportion of variance explained 0.37 0.22 0.13