Objective  The aims were to clarify the effect of application of biochar on fungal community structure of rhizosphere soil under Zanthoxylum bungeanum Maxim, as well as to reveal its main controlling factors.

  Method  High-throughput sequencing, chemical property determination and monitoring for Zanthoxylum Bungeanum growth indicators were conducted on no application of biochar treatment (CK) and three biochar application treatments with rates of 1.0 t hm⁻² (T1), 1.8 t hm⁻² (T2) and 2.6 t hm⁻² (T3).

  Result  The pH, total carbon, total phosphorus, total potassium, available phosphorus, available potassium, C/N and CEC were increased with the biochar application rates in the rhizosphere soil of Zanthoxylum bungeanum. Fungal community Chao 1, ACE and Shannon index decreased with biochar application rates and vice versa for Simpson index. The relative abundance of Ascomycota, Zygomycota and Chytridiomycota were decreased with increased application rates of biochar and vice versa for the relative abundance of Glomeromycota and Basidiomycota. Genus level analysis showed that T2 treatment greatly increased the relative abundance of Ascosphaera, Mortierella and Paecilomyces by 24.3, 3.1 and 1.4 times respectively compared to CK. T3 treatment greatly increased tree height, ground diameter and number of new shoots by 1.7, 2.4 and 2.0 times respectively. Factor and correlation analyses showed that soil pH, C/N, available phosphorus, total nitrogen and total carbon cumulatively explained 81.2% of the community variation. Soil pH, C/N, effective phosphorus, total carbon and the fungus Simpson showed significant or highly significant positive correlations with this tree growth indicators, but Chao 1 and Shannon showed highly significant negative correlations with its growth indicators.

  Conclusion  Application of biochar from rice straw could significantly improve soil quality, reduce fungal community richness and diversity, and increase the proportion of beneficial fungal genera such as Ascosphaera, Mortierella and Paecilomyces. T3 (biochar 2.6 t hm⁻²) is the recommended treatment based on the promotion considerations, and T2 (biochar 1.8 t hm⁻²) is the recommended treatment based on the physiological role of beneficial functional bacteria.