NUTRIENT CONTENTS OF SPRUCE NEEDLES FROM THE TYROLEAN LIMESTONE ALPS

The nutrient concentrations in the needle samples of the Bio-lndicator Grid were used to evaluate the nutrient situation in the Northern Tyr olean Limestone Alps. The poor nitrogen supply, which was proved in th e framework of the Austrian Bio-Indicator Grid, was found also in the Tyrolean Limestone Alps. In addition, a marked deterioration of the nu trient situation was observed during the period under investigation (1 983-1992). It is assumed that the weather played an important part in this unfavourable development (lack of precipitation and significantly higher temperatures during the vegetation periods, particularly in 19 92). The concentrations of phosphorus and potassium remained approxima tely the same; the calcium content increased. The most frequent types of deficencies were nitrogen, phosphorus, and NP deficiencies. In 1992 , a marked decrease in the magnesium concentrations was found. General ly, the altitudinal zone between 1000 m and 1200 m showed the worst nu trient situation, which can also be seen from the fact that, during th e last five years of investigation, samples from that zone had the low est concentrations of N, P and Mg.. So the nitrogen nutritiant situati ons of the needles of the area of Achenkirch was poor from the very be ginning, it was not possible to show the significant deterioation of t he situation of the Tyrolean Limestone Alps in the area of Achenkirch. A remarkable improvement of the nutrient situation was observed at th e high-altitude sub-alpine sample plot (Schulterberg). As opposed to t he results from the Limestone Alps, which did not show any significant changes regarding the supply with K and Ca during the same period, th e K supply deteriorated in the area of the ''Achenkich Altitude Profil es''; and the calcium supply improved remarkably. Different results we re also obtained in respect of the Mg supply which, until 1990, improv ed in the Limestone Alps, but after that deteriorated clearly, while i t remained almost at the same level in Achenkirch during the entire pe riod. In both areas of assessment the mean P concentrations remained t he same.