Characteristics of plant concentration ratios assessed in a 64-site field survey of 23 elements

Many of the statistical characteristics of plant concentration ratios (CRs) and translocation factors (TFs) have not been critically assessed, especially in field surveys. The statistical characteristics, particularly the measures of variation, are important for stochastic modelling of plant uptake. The CR and TF values for 23 naturally occurring elements throughout the geographic range of one plant species, blueberries (Vaccinium angustifolium), in Canada were surveyed. Although the ratios imply linear relationships, the numerator concentrations were not closely correlated with the denominator concentrations. The variation in the ratios was not clearly related to the means or to characteristics of the elements. The overall geometric standard deviation for CRs was 2.5 and for TFs was 1.6. The values of CR were intercorrelated for certain groups of elements and these groups reflected the periodic classification of elements. Thus, correlation between elements in stochastic models, which may reduce overall variability, is valid. Site variables such as soil pH, soil bulk density, soil fertility and plant growth condition were only slightly useful in statistically explaining some of the variation in CR values. (author)