A century-long snow avalanche chronology reconstructed from tree-rings in Parâng Mountains (Southern Carpathians, Romania)

Abstract

Snow avalanches are common processes on steep slopes of the alpine and subalpine belts in Parâng Mountains (Southern Carpathians, Romania). The increasing tourism activities in these high mountain areas expose tourists to a high level of hazard especially in the avalanche prone areas, where the past avalanche activity is poorly documented. Snow avalanches also affect coniferous and mixed forests, offering the opportunity to analyze disturbed trees and date past events with a one-year resolution. In this work, we present the results of the dendrogeomorphic reconstruction in terms of frequency and spatial extent of past snow avalanches occurred in the past along the Zăvoaie avalanche path located on the NE slope of Parângul Mic peak (2519 m a.s.l.). A total of 57 Norway spruce (Picea abies (L.) Karst.) disturbed by snow avalanches was sampled, and their growth reactions (scars, callous tissues, compression wood and traumatic resin ducts) identified within tree-rings served as basis for establishing a calendar of past events with one-year resolution. The analysis of tree-rings allows reconstruction of a minimum of 12 avalanche events spanning 1900–2013. In the absence of historic documented events (except in the case of the 1997 event), dendrogeomorphic methods are a reliable tool to reconstruct the snow avalanche activity within the studied path. These results provide a better understanding of the local snow avalanche frequency, magnitude and return periods. These may be included in the present hazard mitigation planning or future decision making in this area, in order to reduce exposure of tourists and related infrastructure to this hazard.