Multidecadal Trajectories Of Soil Chemistry And Nutrient Availability Following Cutting Vs. Burning Disturbances In Upper Great Lakes Forests

What are the successional trajectories and impacts of disturbances on forest soil nutrient availability? Answers remain elusive because the time scale of interest is long and many factors affect soil properties. We address this question on a regionally representative landscape in northern Michigan, U.S.A. Late-successional reference stands aside, most forests on this landscape were clearcut and burned between 1870 and 1911; subsequently, stands comprising two chronosequences were either cut and burned again, or cut only, at multidecadal intervals. Influences of disturbance and succession were detectable in A, B, and C horizons, particularly for properties affected by ash deposition: pH, Ca, and Mg declined with age but were higher in twice-burned stands. A horizon NH4+ was lower in twice-burned than once-burned stands and declined with age in both chronosequences. B horizon Fe increased with age in both chronosequences but remained lower in twice-burned stands, suggesting slower recovery of pedogenesis following more severe disturbance. Contrasted against A and B horizons, where soil properties were driven by disturbance and succession, textural influences were evident in C horizons through variation in Ca, Mg, K, Al, and cation exchange capacity. Collectively, these results indicate deep, long-lasting disturbance impacts and a bottom-up influence of parent material at the landscape level.