Plantation soil inoculation combined with straw checkerboard barriers enhances ectomycorrhizal colonization and subsequent growth of nursery grown Pinus tabulaeformis seedlings in a dryland

Abstract Aeolian desertification is the dominant form of land degradation in drylands. The straw checkerboard barrier (SCB) method is effective for sand fixation and has been used to combat aeolian desertification in China. Soil inoculation with ectomycorrhizal (ECM) fungi can help restore degraded lands by improving the soil microbial community and steering plant community development. Combining SCB with afforestation via planting ECM trees and inoculating soil with ECM fungi holds promise for improving plant establishment and growth on shifting sand dunes, but this has yet to be examined. Here, we tested the effects of soil inoculation on ECM colonization of Pinus tabulaeformis roots and the survival and establishment of nursery grown P. tabulaeformis seedlings using three soil treatments: no soil (NS), soil sterilized with fungicide (FPS), and ECM-containing non-treated plantation soil (NPS) collected from a nearby P. tabulaeformis plantation. After two years, P. tabulaeformis survival did not differ among the three soil treatments, but ECM colonization rate, total plant dry weight, and leaf total nitrogen per one seedling in the NPS treatment were 9.0, 2.6, and 3.4 times higher than those in the NS treatment. Water use represented by leaf δ13C was also highest in the NPS treatment. Structural equation modeling showed that soil inoculation enhanced ECM colonization of P. tabulaeformis, thus improving nitrogen uptake and water use, leading to increased plant growth. Suillus, Peziza, Geopora, Tuber, and Tomentella were the dominant genera in NPS treatment; 94% of the ECM roots in the NPS treatment were colonized by ECM fungi not detected in NS treatment, indicating that ECM fungi from the inoculum soil were able to colonize the roots of nursery grown seedlings. Only a few ECM fungal species could colonize P. tabulaeformis roots from the plantation soil inoculated, but the taxonomic diversity including Basidiomycota and functional diversity of mycelial exploration types were increased by soil inoculation. These results suggest that soil inoculation with ECM fungi aids in afforestation with ECM plants for the restoration of degraded drylands, including shifting sand dunes.