关键词: 杨树人工林, 高通量测序, 根序, 根际土壤, 真菌群落

Abstract: We investigated the regeneration composition of woody plant species in the gaps with different characteristics (gap size, gap age, and causes of gap formation) in Maolan Karst forest by calculating the importance values, density, and richness of woody species, and analyzing the relationships between their regeneration and different gap characteristics. Our results showed that gap size significantly affected the density and richness of woody species. Both the density and richness of shadetolerant species (0.32 individual·m^-2 and 3.26 species·m^-2, respectively) and intermediate shade-tolerant species (0.40 individual·m^-2 and 2.54 species·m^-2, respectively) in large gaps (>200 m²) were significantly higher than those in small gaps (≤200 m²), suggesting that large gaps (>200 m²) could provide suitable light conditions and growth environment for shade-tolerant species and intermediate shade-tolerant species. Dominant species in young gaps were shade-tolerant species, with an importance value of 0.377. Dominant species of middle-aged gaps were intermediate shade-tolerant species, with an importance value of 0.400. Dominant species of old gaps were shade-intolerant tree species, with an importance value of 0.325. Those results suggested that shade-intolerant species gradually became dominant with the increasing gap age. The cause of forest gap formation had a significant effect on the density of woody species. The density of intermediate shadetolerant species (0.43 individual·m^-2) and shadeintolerant species (0.43 individual·m^-2) in the gaps caused by the lianas twining was significantly higher than that that in the gaps caused by the artificial cutting, disease, or insect pests, suggesting that the gaps caused by lianas twining could provide suitable conditions for shadeintolerant species and intermediate shadetolerant species.

Key words: rhizosphere soil, fungal community, poplar plantation., root orders, high-throughput sequencing