INVESTIGATIONS ON MYCORRHIZAE AND FINE ROOTS IN AN AREA USED AS FOREST PASTURE

On the Schulterberg, at an altitude of 1640m as.l. (Achenkirch project area), investigations on mycorrhiza and fine roots were carried out a t the end of the 1991 grazing season in an area used as pasture. The e valuation of 900 cylinder samples (100 mi), taken from an area of 400 m(2), showed considerable differences between small forest and pasture sites. Where there were trees the dry weight and the density of mycor rhizae and fine roots were higher. The diversity of the mycorrhizae an d their vitality were those of a healthy forest in good condition. In areas used for grazing dead mycorrhizae and fine roots were frequently found. It is assumed that this damage, as well as the resulting poore r vitality, is due to the mechanic stress of the soil caused by grazin g cattle or sheep. It is evident that the quantitative features which can be established in respect of mycorrhizae do not provide sufficient information to allow an evaluation of the site quality and that quali tative features must be taken into account for that purpose. No pollut ant-related deformation of mycorrhizae was observed. From seed experim ents, which can be used to assess natural regeneration, the following results have been obtained: The roots of 2-year old seedlings develope d poorly on sites used for grazing, moderately around trees, and well or even very well, on rotting wood. The feature assessed was the lengt h of the roots. The development of the mycorrhizae also proved to be h eavily dependent on the substrate and, therefore, can be used as-a sit e indicator.