Forest mycorrhizal dominance depends on historical land use and nitrogen‐fixing trees

Abstract Most forests are recovering from human land use, making it critical to understand the effect of disturbance on forest recovery. Forests eastern United States have a long history but is unknown whether historical disturbances contributed their transition ectomycorrhizal (ECM) arbuscular mycorrhizal (AM) tree dominance. Disturbance may promote nitrogen (N)‐fixing trees in early succession, which can elevate soil N availability even after they die. Higher facilitate competitive success AM over ECM trees, such ‘N fixer founder effects’ not been empirically tested. Here, we analysed data three land‐use temperate historically dominated by trees: selective‐cutting (ranging 0 52 m 2 ha −1 ), clear‐cutting and agricultural abandonment. These occurred at different times, long‐term capture 3–7 decades We found that fraction contemporary was 2, 4, 6‐fold higher following selective‐cutting, abandonment, respectively, compared composition 1934. Across these also observed an increasing abundance black locust immediately disturbance. Using simulation model parameterized locust, estimated rates symbiotic fixation relationship between dominance individual plots. positively associated with growth generally, oak hickory specifically, only light (<12 or <18 basal area extraction, respectively). Following levels clear‐cutting, particularly red maple tulip poplar. Agricultural abandonment led regardless rates. Synthesis applications . Our findings suggest common use practices native fixer, reduce trees. If fixers likely proliferate disturbance, might maintain cutting low densities applying prescribed fire remove N.