Spatial distribution of damages caused by wind storms in treestands of the Tuchola Forest

Abstract

This paper presents the application of Geographical Information System in the analysis of spatial distribution of wind-induced damages in the forest landscape. Those damages were caused mainly by hurricanes, which took place on the 26th of December 1999 and 22nd of June 2000. Location and extent of damages were determined in the whole territory of the Tuchola Forest region in Northern Poland. The analysis of influence of the landscape structure and history of land use on localization and frequency of occurrence of root and stem breakages was carried out at four sites delimited in forest inspectorates Woziwoda, Przymuszewo and Czersk as well as in the Bory Tucholskie National Park, where the extent of damages was the highest one. The aim of this work was to find answers to four questions: 1 – does a closer location of forest towards a field-forest boundary increases the extent of damages in a forest stand?, 2 – are wind-induced damages more severe in secondary forests reconstructed on formerly arable lands than in forests, the development of which was not interrupted by temporal agricultural land use after cutting down the trees?, 3 – what influence has the terrain orography on the intensity and extent of wind-induced damages? 4 – to what extent root throws and stem breakages change the canopy structure? In order to determine changes in the extent and distribution of the forest and agricultural area in the study terrain as well as to identify secondary forests, old and contemporary topographic maps were used, as well as forest economic maps, satellite images Landsat 7ETM+ dated 2000 and Ikonos dated 2003. Information derived from the above mentioned sources as well as data obtained from forest stocktaking and direct field measurements carried out with the GPS receiver, were arranged in the geographic information system. The statistical analysis conducted with the GIS technology, applying computer programs MicroStation/Bentley, ESRI ArcView3.2 and Idrisi 32, proved that factors such as neighbourhood of large non-forest areas as well as temporal agricultural use of forest soils indeed increase the extent and frequency of occurrence of damages caused by strong wind in the canopy of forest ecosystems.