4.2 Effect of N addition on the structure and diversity of AM fungi community
Different N addition content and local soil conditions affect plants and soil microorganisms (Cao et al., 2020; Zeng et al., 2021). In this study, both high-throughput sequencing and traditional spore morphological identification were used to investigate the community structure and diversity of woodland AM fungi. Morphological identification has inconsistencies, limitations, and chances, but can be improved by means such as increasing the sample size. High-throughput sequencing technology has been widely used by researchers, but stills has some limitations. Due to the variety of microorganisms, the current database cannot cover all the microorganisms or lacks accurate species information, resulting in the omission of some low-abundance species, so we combine the two methods to accurately reflect the diversity and structural characteristics of AM fungi (Chaudhary, Nolimal, Sosa-Hernandez, Egan , & Kastens, 2020). Both high-throughput sequencing results and morphological identification results showed that N addition altered AM fungi community composition and reduced AM fungal alpha diversity.
It is clear from the RDA analysis (Fig. 5) that pH significantly affected the community composition of AM fungi in Korean pine plantation, and there was research reported that soil pH was one of the most important abiotic factors affecting the ecological distribution of AM fungi (Davison et al., 2021). The abundance of Glomusincreased gradually (Fig. 4) with increasing N addition concentration and was significantly higher in the HN treatment, the main reason for this phenomenon being that Glomus showed a better ecological advantage in acidic soils. In the experiments of (Cao et al., 2020), short-term HN treatment (80 kg N ha-1year-1) also reduced fungal diversity and changed community composition. It is believed that this phenomenon is caused by the change of P elements in the soil due to N addition, which causes plants to select AM fungi with high phosphorus absorption capacity