ORIGINAL PAPER GIS-based estimation of the winter storm damage probability in forests: a case study from Baden-Wuerttemberg (Southwest Germany) Dirk Schindler & Karin Grebhan & Axel Albrecht & Jochen Schönborn & Ulrich Kohnle Received: 28 October 2010 / Revised: 15 December 2010 / Accepted: 15 December 2010 / Published online: 5 January 2011 # ISB 2011 Abstract Data on storm damage attributed to the two high- impact winter storms ‘Wiebke’ (28 February 1990) and ‘Lothar’ (26 December 1999) were used for GIS-based estimation and mapping (in a 50×50 m resolution grid) of the winter storm damage probability (P DAM ) for the forests of the German federal state of Baden-Wuerttemberg (Southwest Germany). The P DAM -calculation was based on weights of evidence (WofE) methodology. A combination of informa- tion on forest type, geology, soil type, soil moisture regime, and topographic exposure, as well as maximum gust wind speed field was used to compute P DAM across the entire study area. Given the condition that maximum gust wind speed during the two storm events exceeded 35 m s -1 , the highest P DAM values computed were primarily where coniferous forest grows in severely exposed areas on temporarily moist soils on bunter sandstone formations. Such areas are found mainly in the mountainous ranges of the northern Black Forest, the eastern Forest of Odes, in the Virngrund area, and in the southwestern Alpine Foothills. Keywords Winter storm ‘Lothar ’ . Winter storm ‘Wiebke’ . Storm damage . Weights of evidence methodology . Annual booking records Introduction Wind is a major agent of the natural disturbance regime in European forests. Among natural disturbances, wind- storms have accounted for the largest fraction of total damage in European forests between 1950 and 2000 (Schelhaas et al. 2003). Damage to forests occurs if the wind load on trees exceeds the trees’ resistance to either breakage or overturning (Quine and Gardiner 2007). Catastrophic storm events produce damage at diverse spatial scales ranging from individual treefall to entire forest stands. The spatial pattern of storm damage in forests varies not only with the near-surface wind field during severe storms; soil conditions, tree and stand characteristics, topography, silvicultural treatment, and previous disturbance may also influence the severity of damage at a particular geographic location. In general, the occurrence of high impact winds in Central Europe can be attributed to either thunderstorms or deep cyclones. While thunderstorms typically have diameters between 2 and 50 km (local storms), cyclones have much greater diameters of 1,000 km or more. The main cause of the development of thunderstorms is a high-reaching unstable stratification of the atmosphere— conditions often met in summer. The most striking structural feature of cyclones is their front. Basically, mid-latitude cyclones in the North Atlantic-European region originate from the large temperature contrast between warm subtropical air masses and colder polar air masses over the Atlantic region (Kraus and Ebel 2003). Furthermore, the North Atlantic Oscillation (NAO), which can be characterized by the air pressure fluctuations D. Schindler (*) : K. Grebhan : J. Schönborn Meteorological Institute, Albert-Ludwigs-University of Freiburg, Werthmannstr. 10, Freiburg 79085, Germany e-mail: dirk.schindler@meteo.uni-freiburg.de A. Albrecht : U. Kohnle Forest Research Institute of Baden-Wuerttemberg, Wonnhaldestrasse 4, Freiburg 79100, Germany Int J Biometeorol (2012) 56:57–69 DOI 10.1007/s00484-010-0397-y