The effects of liming and gypsum applications on a sessile oak (Quercus petraea (M.) Liebl.) stand at La Croix-Scaille (French Ardennes) I. Site characteristics, soil chemistry and aerial biomass

In a former 45 to 50 year old sessile oak (Quercus petraea (M.) Liebl.) cop pice mixed with birch (Betula pubescens Ehrh.) and rowan (Sorbus aucuparia L.) on a poor acidic forest soil at la Croix-Scaille in the French Ardennes , several liming amendments were applied in 1990 and 1994. Data on soil and soil solution composition, as well as stand growth and foliar composition were collected between 1994 and 1997. All treatments, containing 1.4 t ha(- 1) equivalent of CaO supplied as lime, gypsum or a mixture of the two, resu lted in an increase of cation exchange capacity and base saturation down to 15 cm and for CaSO4 treatments down to 30 to 45 cm, increases of soil pH a nd Ca concentration at the surface and a decrease of Al concentration in th e soil and soil solution in the surface layers. No negative effects like in creased nitrate or cation leaching were observed. Although Mg nutrition was not improved by the treatments (not containing Mg), a relative and maintai ned gain of radial increment of sessile oak in the order of 40% for both li me and gypsum applied, was observed immediately from the first year on, aft er the application (1991).