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Interpretation of the nutritional status of forest trees by the Diagnosis and Recommendation Integrated System (DRIS)

Pohl, H.N., Vandré, R., Kaupenjohann, Martin
Forstwissenschaftliches Centralblatt 1999 v.118 no.1-6 pp. 287-293
Diagnosis and Recommendation Integrated System, Quercus robur, calcium, crops, data collection, defoliation, environmental factors, forest trees, leaf analysis, leaves, magnesium, nitrogen, nutrient content, nutrients, nutritional status, phosphorus, potassium, soil quality, sulfates
A data set of leaf analyses of 169 oak trees (Quercus robur and Q. petraea,THOMAS andBüTTNER 1998) was used to examine the suitability of the Diagnosis and Recommendation Integrated System (DRIS), already successfully employed for main agricultural crops, to interpret leaf nutrient concentrations of damaged forest trees. Calculated DRIS-indices confirmed the interpretation by threshold values for N and K. By contrast, the elements P and Mg, identified by threshold values as being deficient, showed a good balance by DRIS-indices. Further, Ca and SO₄²⁻, which have not attracted any attention by threshold interpretation, were greatly imbalanced nutrients in damaged trees (criterion: degree of foliage ≤80%) in comparison to undamaged trees (norm population; criterion: degree of foliage >80%). In pedunculate oaks Ca-indices were significantly positively, SO₄²⁻ and S-indices significantly negatively correlated with the degree of foliation. In sessile oaks this was only significant for SO₄²⁻- and S-indices. These elements can be interpreted as indicators for soil conditions. For both species, the Nutrient-Balance-Index (NBI) was negatively correlated with the degree of foliation. This means, that the entire imbalance of the nutritional status increased with increasing defoliation. Pedunculate oaks might be generally less balanced nourished as sessile oaks, due to the more elevated athmogenic depositions at the sites of pedunculate oak stands. The present investigation indicates that DRIS has a considerable potential for interpretion of foliar nutrient concentration analyses of damaged forest trees. Further investigations should be applied to test and improve it by integrating site factors.