Ecosystem multifunctionality in temperate forests of South Korea is primarily controlled by structural diversity and...

Assessing and improving ecosystem multifunctionality (EMF) is essential to achieving the goals of enhancing human well-being and sustainable development. This study aims to quantify EMF and to identify its influencing factors, including biotic (tree species diversity, functional dominance, and stand structural diversity) and abiotic factors (topography, climate, and soil), and stand age. We used South Korea's 7th National Forest Inventory data to analyze 630 natural forest plots consisting of coniferous, broadleaved, and mixed stands. We categorized 12 ecosystem function-related variables to quantify EMF. Multimodel averaging and piecewise structural equation modeling were implemented to identify the main variables that affect EMF and to quantify their interrelationships and strengths. Additionally, we quantified the strength of interactions between ecosystem functions. Our findings indicate that high plant richness and old forests led to high stand structural diversity, which has a direct positive effect on EMF. Additionally, reducing water stress increased the availability of plant resources, which also has a positive effect on EMF. The mechanism controlling EMF differed according to forest stand type. In particular, we did not observe dominant plant functional traits controlling EMF in mixed stands due to the mixture of functional traits of coniferous and broadleaved trees. Finally, the interactions among ecosystem functions demonstrated a stronger synergy effect, with most functions contributing to an increase in EMF, though the degree of impact varied depending on the forest stand type. Our analysis indicates that we must comprehensively consider biodiversity and stand age as well as stand structural diversity to promote EMF. Moreover, forest management strategies should account for the interaction between plant functional traits and ecosystem functions along with environmental gradients is essential.