Influence of shifts over an 80-year period in forest composition on soil properties.

Background and aims: Forest composition in North America has undergone important changes since the European settlement. The effects of such alterations on soil properties remain largely unknown. This study aims to understand the long-term effects of shifts in forest composition on soil properties. Methods: Using data from 130 plots measured over an eighty-year period, the relationships between stand composition (both current and past), parent material and current soil chemical properties were studied with redundancy analyses. Results: Results indicated that the parent material remained the dominant factor explaining soil properties, followed by current tree species composition. No legacy effect of past forest composition was found, but shifts in forest composition explained part of the current soil properties. Specifically, an increase in balsam fir was related to higher C/N ratio in the O-horizon, while an increase in maple species was related to higher net nitrification in both the O and B-horizons, and higher extractable P in the B-horizon. Conclusion: Our results suggest that increasing the maple component at the expense of conifers over several decades may enhance nutrient availability in the O-horizon.