Intercropping Flowering Plants Enhances Multiple Ecosystem Services in Apple Orchards

Intercropping flowering plants is an ecofriendly and sustainable orchard management practice, yet its effects on multiple ecosystem services remain poorly understood. To address this knowledge gap, we conducted a two-year field experiment using four species of intercropped flowering plants, including Sechuangzi Cnidium monnieri (L.) Cusson (Apiaceae), Japanese catnip Schizonepeta tenuifolia Briq. (Lamiaceae), rapeseed Brassica napus L. (Brassicaceae), and hairy vetch Vicia villosa Roth. (Fabaceae), in an apple orchard. We selected 22 ecosystem service indicators to establish a comprehensive framework for assessing orchard ecosystem services. In 2020, 19 indicators differed significantly between intercropped flowering plant plots and clean-tillage control plots, while 18 indicators showed significant differences in 2021. The ecosystem service indicators were grouped into six composite multifunctional indicators representing pollination, pest control, habitat provisioning, food provisioning, nutrient cycling, and carbon stock, all of which showed significant enhancement in flowering plant plots compared with the controls. Crucially, these six composite indices demonstrated synergistic interactions, with no trade-offs observed. Compared to clean-tillage control plots, total ecosystem services in 2020 increased by 228% in C. monnieri plots, 222% in B. napus plots, 217% in V. villosa plots, and 126% in S. tenuifolia plots; in 2021, the increases were 248%, 214%, 209%, and 115%, respectively. Overall, these results suggest that intercropping selected flowering plants can improve multiple measured ecosystem service indicators in apple orchards. This practice may provide a promising orchard-floor management strategy for enhancing ecosystem service multifunctionality under the conditions of this two-year field experiment.