Restoration Approaches Regulate Soil Multifunctionality via Microbial Nitrogen and Plant Diversity in Northern Forests.

Long-term anthropogenic disturbances have damaged forest ecosystems, and different restoration approaches after disturbance play a crucial regulatory role in maintaining and enhancing ecosystem functions. However, existing studies have mostly focused on the response characteristics of single ecosystem functions, while research on the impacts of different restoration methods on soil multifunctionality of forests and their driving mechanisms remains scarce. Taking the completely anthropogenically disturbed Quercus wutaishanica communities in northern deciduous broad-leaved forests as the research object, this study systematically explored the comprehensive effects of two typical restoration approaches (natural restoration and artificial assisted restoration with Larix principis-rupprechtii) and soil layer depths (0-10 cm, 10-20 cm) on soil microbial biomass and soil multifunctionality after 40 years of restoration, and further revealed the dominant driving factors of soil multifunctionality. The results showed that: (1) Artificial assisted restoration markedly increased soil microbial phosphorus content by 97.52% ± 28.86%; with increasing soil depth, both soil microbial carbon and nitrogen contents decreased significantly, by 24.18% ± 6.14% and 7.89% ± 2.12%, respectively. (2) Artificial assisted restoration communities exhibited a significantly higher soil multifunctionality index (0.34) compared with natural restoration communities (-0.37). Further analysis indicated that soil multifunctionality was mainly driven by soil microbial nitrogen content and the Pielou evenness index of plant community composition. This study provides notable theoretical supports and practical references for the sustenance, renewal and management of damaged ecosystems in northern deciduous broad-leaved forests.