The effects of land restoration techniques on mycorrhizal colonization in post‐agricultural soils

Restoration of agricultural lands through reforestation and planting of native prairies are common ways of promoting soil recovery and remediating soil carbon loss. The presence of mycorrhizal fungi in restored sites is essential, as they improve nutrient acquisition for plants and increase soil carbon storage. The recovery of nutrient cycling, predominantly carbon, following the conversion of agricultural lands is widely studied, but few studies have examined how mycorrhizal colonization changes over time after restoration, how soil physical properties and colonization differ in restored prairies versus forests, and which soil characteristics are associated with colonization. We studied mycorrhizal colonization in a chronosequence that included restored prairies and forests ranging from 3 to 70 years old and a conventional agricultural field in Knox County, Ohio. We analyzed differences in soil pH, soil organic matter (SOM), phosphorus, and soil texture to determine which variables best predicted mycorrhizal colonization. Results from our chronosequence indicated that restoration technique did not influence colonization over time. We observed a 110% increase in root length colonized in prairies and a 109% increase in forest sites over the chronosequence. Site age and soil sand content were significant predictors of colonization, as age positively correlated and % sand negatively correlated with colonization. SOM was weakly positively correlated with colonization levels. We conclude that restoration of agricultural lands has the potential to increase the abundance of belowground microbial communities and increase carbon storage. Mycorrhizal fungi should be considered as an indicator of restoration success due to their role in remediating soil health and nutrient pools.