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Abstract
Land-use disturbance alters the nitrogen (N) cycle in ecosystems, yet the mechanisms that lead to altered N cycling are unclear. We investigated how the degree of disturbance alters the N cycle long-term through symbiotic nitrogen fixation (SNF) and mycorrhizal dominance at the landscape scale. We found that increasing disturbance intensity led to increased SNF and, subsequently, increased arbuscular-mycorrhizal dominance. In turn, we found that arbuscular-mycorrhizal dominance indirectly led to increased N transformation rates, N pools, and the abundance of N cycling microbial genes through soil acid-base chemistry. Our study presents a mechanism through which ecosystem processes are altered long-term and shows that when early-successional N-fixing trees are present, they have the potential to create biogeochemical founder effects that influence trajectories of ecosystem recovery for decades.