Predicting magnesium concentration in needles of Silver fir and Norway spruce—a case study

Different geostatistical methods are used to interpolate the spatial distribution of the foliar magnesium content of Silver fir and Norway spruce in the Black Forest. The data analysed are from a monitoring survey carried out in 1994 in the forest of Baden-Württemberg, a federal state in the south-west region of Germany. In this survey many potential explanatory variables are collected. The aim of this paper is to identify the best prediction method that can be useful in the future for cause–effect studies and environmental modelling. At the same time, causal relationships between the response variable and the predictors are investigated. Therefore, geostatistical methods with lowest prediction errors which simultaneously provide the highest explanation value had to be identified. The performance of different methods is measured using cross-validations techniques.