Tree species effects on solution chemistry and major element fluxes: A case study in the Morvan (Breuil, France).

Forest plantation is a widely used silvicultural practice throughout Europe most particularly to renew planted forest stands. The long term impact of forest plantations on soil fertility is a major concern for forest managers and policy makers, in particular in the context of global change because forests endure increased climatic and/or silvicultural and/or nutritional pressure. In the present study we investigated the tree species effects on soil solution chemistry and major elements fluxes, to better understand the impact of tree species on soil processes and fertility. The chemical composition of throughfall and soil solutions were compared between six 35-year-old monospecific stands (Norway spruce, Corsican pine, sessile oak, European beech, Douglas fir and Nordmann fir) and the reference plot (beech and oak coppice with standards) of the common garden experiment at the Breuil-Chenue Experimental site (Burgundy, France). Tree species had a strong effect on the chemistry of throughfall and soil solution, in particular on the relative contribution of nitrate, sulfate and dissolved organic carbon to the anionic charge. Mean concentrations of major elements varied widely between stands. Nitrate concentrations were highest for the Douglas fir and Corsican pine probably due to the tree species effect on nitrification processes. In both stands, the nitrate leaching causes large acidification with high drainage losses of magnesium, calcium and monomeric aluminum. For Norway spruce, sessile oak, European beech and reference plot, sulfate and dissolved organic carbon were the main anionic drivers for solution chemistry and nutrient fluxes. Soil acidification processes were less intense in these stands and aluminum was mainly transported in the soil profile by Al-cheluviation by dissolved organic compounds. The results of this study suggest that tree species strongly influence the chemistry of throughfall and soil solutions and may strongly influence on the short-term (35 years) soil pedogenic processes from weak acidification and crypto-podzolisation to strong soil acidification. [ABSTRACT FROM AUTHOR]