J. D. Sauerländer's Verlag, Bad Orb

Following the great Rhine flood of early summer 1999, the Gewässerdirektion Südlicher Oberrhein (local water agency, now within the Department of the Environment of the district government) has commissioned a survey of the mortality of 2955 total trees and tree groups from the alluvial forest. The mortality risk for European ash (Fraxinus excelsior), Sycamore maple (Acer pseudoplatanus), Norway maple (Acer platanoides) and wild cherry (Prunus avium) was assessed by using logistic models according to tree- and flooding characteristics. An intra-species comparison shows that wild cherry trees suffer from a significantly higher mortality rate than other tree species of the same size class when exposed to the same flooding event. By applying a cutpoint analysis, threshold values were calculated for a combination of independent parameters of the DBH, flood duration and flood height until a tolerable mortality was reached. The analysis of the correctly classified observations, as well as the confidence range, point, however, to a great prediction uncertainty of the flood tolerance phenomena. Simulations of flooding scenarios nonetheless reveal a general trend for a tree-specific die-off pattern for the selected tree species in the Upper Rhine River alluvial forests.

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