Long-Read Sequencing Analysis Revealed the Impact of Forest Conversion on Soil Fungal Diversity in Limu Mountain, Hainan.

Soil fungi are essential to soil microorganisms that play an important role in the ecosystem's soil carbon cycle and mineral nutrient transformation. Understanding the structural characteristics and diversity of soil fungal communities helps understand the health of forest ecosystems. The transition from tropical rainforest to artificial forest greatly impacts the composition and diversity of fungal communities. Hainan Limushan tropical rainforest National Park has a large area of artificial forests. Ecologists have conducted in-depth studies on the succession of animals and plants to regenerate tropical rainforests. There are few reports on the diversity of soil fungi and its influencing factors in the succession of tropical rainforests in Limu Mountain. In this study, 44 soil samples from five different stands were collected in the tropical rainforest of Limushan, Hainan. High-throughput sequencing of rDNA in its region was used to analyze fungal communities and study their α and β diversity. Analysis of variance and multiple regression models was used to analyze soil variables and fungal functional groups to determine the effects of interaction between fungi and environmental factors. A total of 273,996 reads and 1290 operational taxonomic units (OTUs) were obtained, belonging to 418 species, 325 genera, 159 families, eight phyla, 30 classes, and 73 orders. The results showed that the composition of soil fungal communities in the five stands was similar, with ascomycetes accounting for 70.5% and basidiomycetes accounting for 14.7%. α and β diversity analysis showed that soil fungi in Limushan tropical rainforest had high abundance and diversity. Multiple regression analysis between soil variables and functional groups showed that organic matter, TN, TP, TK, and AK were excellent predictors for soil fungi. TP was the strongest predictor in all functional groups except soil saprotroph. Organic matter and total nitrogen were the strongest predictors of soil rot. The transformation from tropical rainforest to artificial forest in Limushan did not change the soil fungal community structure, but the richness and diversity of soil fungi changed. The forest transformation did not lead to decreased soil fungal abundance and diversity. Different vegetation types and soil properties affect the diversity of soil fungal communities. We found that Caribbean pine plantations can improve soil fungal diversity, while long-term Eucalyptus spp. plantations may reduce soil fungal diversity.