Plant Functional Traits and Soil Nutrients Drive Divergent Symbiotic Fungal Strategies in Three Urban Street Tree Species.

Understanding species-specific mechanisms governing symbiotic fungal responses to plant traits and soil factors is critical for optimizing urban tree "plant-soil-fungus" systems under pollution stress. To address this gap, we combined δC/δN isotope analysis and ITS sequencing for three common street trees in Beijing: , , and . In , symbiotic fungal abundance was positively associated with leaf δN, indicating root exudate-mediated "plant-microbe" interactions during atmospheric NO assimilation. , with weak NO assimilation, exhibited a negative correlation between fungal abundance and soil available N/P, suggesting mycorrhizal nutrient compensation under low fertility. showed decreased fungal abundance with increasing soil N/P ratios and specific leaf area, reflecting carbon allocation trade-offs that limit mycorrhizal investment. These results demonstrate that symbiotic fungi respond to atmospheric and edaphic drivers in a tree species-dependent manner. Urban greening strategies should prioritize for its NO mitigation potential and optimize fertilization for (nutrient-sensitive fungi) and (nutrient balance sensitivity). Strategic mixed planting of with could synergistically enhance ecosystem services through complementary resource acquisition patterns. This study provides mechanism-based strategies for optimizing urban tree management under atmospheric pollution stress.