Use of Ornamental Trees in Dating of Abandoned Cemeteries on the Example of Thuja Occidentalis and Thuja Orientalis

Abstract

Due to the lack of maintenance, abandoned cemeteries are often incorporated into the landscape. In many cases the information about the age of the cemetery is unavailable. To find out the approximate time of the formation of the cemetery the information recorded in the annual tree and shrub rings can be used. One of the most common tree species, planted for ornamental and symbolic purposes on the cemeteries, are Thuja orientalis and Thuja occidentalis. Alien to the Polish flora, these species adapted well to the local habitat and climatic conditions. The paper presents an attempt to apply dendrochronological dating to determine the age of the abandoned cemeteries in the region of the Great Masurian Lakes, part of the Masurian Lake District (north-eastern Poland). The study included five abandoned cemeteries. In total, 15 cores were taken from the trees. After applying the standard dendrochronological method, local chronologies for the studied species were established. The research indicated that the oldest found specimens - over 70 yrs old - are Thuja occidentalis individuals growing at the Słabowo cemetery. At the other sites the specimens of both Thuja species date back to the 1960s and early 1970s. Compared to the historical information regarding the age and origin of the studied objects, thujas growing there are much younger than the age of the cemeteries foundation. The presented method proved to be very helpful in understanding the time of Thuja occidentalis and Thuja orientalis introduction at the investigated cemeteries.