Activity of slow-moving landslides recorded in eccentric tree rings of Norway spruce rrees (Picea Abies Karst.) - an example from the Kamienne MTS. (Sudetes MTS., Central Europe

Abstract

We found ubiquitous evidence of ongoing slope instability by analysing the vari-ability of tree-ring eccentricity index in trees growing on three apparently relict landslide slopes in the Sudetes (Poland, Central Europe). Slow movement of these landslide bodies occurs in the present-day conditions and is recorded almost every year, although with vari-able intensity. Correlation of dendrochronological record with the rainfall record from a nearby station in Mieroszów for the 1977–2007 period is very poor for two deep-seated ro-tational slides at Mt Suchawa and Mt Turzyna but considerably better for a shallow flow-slide at Mt Garbatka. While this may reflect higher permeability of heavily jointed rocks involved in deep-seated sliding this could be linked with imperfections in the rainfall rec-ord. Dendrochronology proved capable of detecting minor displacements within landslides which otherwise show no geomorphic evidence of recent activity. Therefore, claims for the entirely relict nature of the landslides are not substantiated.