Alfalfa mulching improved soil health and ecosystem multifunctionality of Camellia oleifera forests on a subtropical karst brae

Introduction Despite the economic, ecological, medicinal and horticultural importance as well as national strategic importance of edible oil security, Camellia oleifera suffers from low yields due to poor soil health and poor floor managements. Whether alfalfa mulching improves soil health remains largely unknown in Camellia oleifera forests. Methods This study quantitatively compared soil health and ecosystem multifunctionality under alfalfa mulching and bare control treatments of Camellia oleifera forests on a subtropical karst brae. Results Alfalfa mulching elevated the relative abundance of beneficial bacteria and fungi, reduced the relative abundance of pathogenic fungi, and enhanced soil health and ecosystem multifunctionality. Understory vegetation diversity, soil microbial function, microbial diversity, microbial life-history strategy, microbial community stability, microbial cross-kingdom network stability, and phylogenetic bin assembly could jointly affect both soil health and ecosystem multifunctionality, however, soil microbial function showed the highest individual effects. Discussion This study demonstrates relatively new supports that alfalfa mulching represents a win-win strategy for renovating low-yielding Camellia oleifera forests. The strategy works by shifting focus from above-ground vegetation management alone to integrated management of both above- and below-ground microbial communities—specifically through improving soil microbial function via mulching.