Investigations on the Telluric Microbiological Features of Forest Dieback in Vosges

Summary

The microbiological aspects of forest dieback has been investigated from an inventory drawn up in Norway spruce stands in Vosges area and from an experimental approach in greenhouse. Declining trees have generally less living mycorrhizae than healthy ones.But because of the influence of various factors it’s not possible to reveal a clear relationship between rootlets decline and forest dieback.None of the notorious root pathogens is involved in the alteration of rootlets.A great number of morphological types of mycorrhizae and a great variability among the trees have been observed without any relationship with forest dieback.The principle of experimental design is to subject the soil to various treatements in order to change it’s microbiological balance.The effect of each treatement on development of Norway spruce saplings has been followed. After one growth season in greenhouse the sapling growth is highly improved by some soil treatment especially pasteurization(70°C) indicating that a part of the microflora has a depressive influence on plant growth. These deleterious microorganisms and mycorrhizal fungi play a prominent role in the striking root of sapling on soils coming from dieback forest stands in the Vosges area.