ANALYSIS OF SOIL, ROOTS AND MYCORRHIZAE IN A NORWAY SPRUCE DECLINING FOREST

Decline symptoms have been detected in a Norway spruce (Picea abies (L .) Karst.) stand in Vigo di Ton on the Northeastern Italian Alps. Stud ies were carried out in two close areas which were chosen because of t heir similar stand age and soil type but differences in crown conditio ns. The two areas didn't show marked differences in the chemical and p hysical soil parameters investigated but varied in volume and thicknes s of main horizons. The density of roots was significantly higher in H (healthy) compared to D (damaged) areas considering roots of all diam eters. The percentage of mycorrhization was very high and similar in H and D, showing in D a higher frequency of types with less complex ram ification and a more marked decrease of diversity of types with depth. However, it is concluded that the symptoms of decline didn't have the ir main origin in the belowground conditions which we investigated, be cause of the lack of statistically significant differences between the two areas. (C) 1998 Elsevier Science Ltd.