Physiological activity of ectomycorrhizas in a moderately polluted forest (Ratanica catchment, southern Poland)

Abstract

Ectomycorrhizas of Scots pine (Pinus sylvestris L.) and beech (Fagus sylvatica L.) were sampled in a mature forest ecosystem exposed for more than 40 years to moderate levels of gaseous and dust pollutants. Soil of the forest site was characterised by low pH and accumulation of heavy metals (Pb, Mn, Zn, Cu, Cd, Fe). Mycorrhizal vitality and enzyme activity of the root-surface and soil acid phosphatase (AcPase) were studied at 17 measurement points (0-5 cm soil depth) in relation to the content of inorganic phosphate (Pi) and aluminiumions( Al3+)inthesoil.AnatomyofScotspineandbeechmycorrhizastakenfromdifferentmeasurement points was observed. The concentration ofessential nutrients (C, N, P, Ca, Mg) and the ratios Ca/Al, Mg/AlandN/Pwereanalysedinfineroots.HighconcentrationsofAl3+inthesoil(40-118meqkg-1)andlow levels ofPi (12-44 mg P2O5kg-1) were accompanied by high activity ofthe root-surface AcPase ofpine and beech mycorrhizas (25-67 and 33-86 /./.mol pNP g-1 fresh weight h-1, respectively) and soil AcPase (6.8-22.4 //mol pNP g-1 dry weight h-1). The results indicate that fine tree roots are undoubtedly under stress as evidenced by a disturbance in P uptake and accumulation. However, the high vitality of mycorrhizas and the high Ca/Al ratio in fine roots suggest that the defence mechanisms of mycorrhizas and the rhizosphere are still able to ameliorate the influence of anthropogenic pollution.