In vitro antioxidant, antibacterial and anti-tumor activities of total flavonoids from Elsholtzia densa Benth

The Panxi region of southwestern China, an important ecological barrier in the upper reaches of the Yangtze River, is severely invaded by Ageratina adenophora , yet the effects of this invasion for soil functioning remain poorly understood. To address this gap, we selected Pinus yunnanensis forest plots with slight or heavy A. adenophora invasion, to investigate the effects of invasion on soil multifunctionality and microbial networks. Additionally, we selected heavily invaded plots co-occurring with the nitrogen-fixing tree Alnus cremastogyne to investigate whether co-occurrence with nitrogen-fixing tree mitigates the negative effects of invasion on soil multifunctionality. The results of this study are as follows. First, heavy invasion by A. adenophora significantly reduced soil multifunctionality, and although microbial network stability increased, this functional decline was associated with the modular and functionally constrained architecture of the networks. Second, the coexistence of nitrogen-fixing tree A. cremastogyne significantly mitigated the invasion-related loss of soil multifunctionality. This mitigating effect was underpinned by increased microbial network complexity and connectivity. Third, random forest analyses identified microbial network complexity as the most important biotic predictor of soil multifunctionality, whereas its network complexity was strongly associated with soil nutrient availability and microbial cohesion. Overall, our findings suggest that microbial network complexity may play a more critical role than diversity or stability in maintaining soil multifunctionality following plant invasion. Our study provides critical empirical evidence for managing invasion pressure and preserving soil health in this ecologically vital region.