Stronger functional coupling rather than enhanced ecosystem multifunctionality in mangrove mixed-species plantations versus monocultures

Human sustainable development relies on ecosystem multifunctionality (EMF), which reflects an ecosystem's capacity to sustain multiple functions simultaneously. The impact of species mixing on mangrove ecosystem multifunctionality remains understudied, lacking multidimensional indicator-based assessments. To address this critical knowledge gap, we assessed EMF of two mixed mangrove patterns (LR + SA, BG + SA) and a monospecific SA plantation, applying mean- and threshold-based EMF quantification using 50 soil, water, vegetation, air, and biodiversity indicators. Results showed mixed forests had 13.42% higher EMF than SA monocultures, though this difference was not statistically significant, with no distinction between the two cultivation patterns. Mixed forests exhibited stronger functional coupling, while monocultures showed isolated functions. Soil carbon storage emerged as the core driver of mangrove EMF, with pneumatophore biomass acting as the key regulatory factor. In summary, this study clarified the functional advantages and regulatory mechanisms of mixed mangrove forests, recommending LR + SA for carbon stocks and BG + SA for biodiversity conservation and improvement of soil quality, thereby providing a scientific basis for mangrove ecological restoration.