Thermal specification of the Dendrological Garden... 37 B A L T I C C O A S T A L Z O N E Journal of Ecology and Protection of the Coastline ISBN 1643-0115 Vol. 20 pp. 37-49 2016 ISSN 1643-0115 © Copyright by Institute of Biology and Environmental Protection of the Pomeranian University in Słupsk Received: 17/11/2016 Original research paper Accepted: 29/11/2016 THERMAL SPECIFICATION OF THE DENDROLOGICAL GARDEN IN GLINNA AGAINST THE CONDITIONS OF THE MESOREGION IN THE SZCZECIN COASTAL REGION Jadwiga Nidzgorska-Lencewicz, Agnieszka Mąkosza, Marcin Kubus, Grzegorz Nowak Department of Meteorology and Landscape Architecture, West Pomeranian University of Technology in Szczecin, ul. Papieża Pawła VI 3A, 71-459 Szczecin, Poland e-mail: [email protected] Abstract The paper is an attempt to assess thermal conditions in the Dendrological Garden in Glinna against the conditions of the mesoregion of the Szczecin Coastal Region, as represented by five stations (Lipnik, Ostoja, Szczecin, Świnoujście, Kołobrzeg) in a study period of two years (May 2014- April 2016), based on measurements of air temperature taken at 200 cm a.g.l. Spatial variation of thermal conditions of the analysed area was found to be very large and was statistically confirmed. Mean air temperature in the analysed period in Glinna was 10.2°C which, in comparison with the other stations, proved to be the highest value. The absolute minimum, i.e. -12.7°C, was recorded in Glinna in January 2016 and the absolute maximum of 35.6°C in August 2015. It was shown that for the purpose of the assessment of thermal conditions in Glinna on the basis of mean air tem- perature from the 24-hour period, it is justified to refer to multiannual data from IMGW station in Szczecin. On the grounds of minimum temperature, amplitude, time of occurrence of spring and autumn frosts, as well as the number of days with frost and cold days, it was shown that the Den- drological Garden in Glinna has more favourable thermal conditions than the neighbouring areas. Key words: trees, maximum temperature, minimum temperature, amplitude, frost, cold days, West Pomerania INTRODUCTION The Dendrological Garden in Glinna, near Szczecin, is one of the 38 botanical gar- dens in Poland statutory activity of which includes, among others, attempts to accli- matize the wood plants in particular climatic conditions. The wide range of taxa cul- tivated in Glinna garden is due to mild climatic and microclimatic conditions, unlike these characteristic for other regions of Poland. According to the map by Heinze and 38 Jadwiga Nidzgorska-Lencewicz, Agnieszka Mąkosza, Marcin Kubus, Grzegorz Nowak Schreiber (1984), the arboretum is located in a woody plants frost resistance sub- zone 7a, where the mean minimum temperature from the multiannual period ranges from -15.0°C to -17.7°C. The bioindicator plants of the sub-zone 7a, i.e. the atlas cedar Cedrus libanii subsp. atlantica , holly Ilex aquifolium and cherry laurel Prunus laurocerasus , grow well and do not freeze in such conditions (Kubus 2008, Nowa- kowska and Baran 2007). The approximate date of establishing the dendrological garden is 1880, however, as early as in 1823, there were tree nurseries in the area and non-native tree nursery sections were introduced in 1870. In 1938, in Glinna there were 52 species of non- native tress and 3 species of non-native shrubs (Tumiłowicz 2009). Since 1970 the collection of the arboretum, administrated by Gryfino Forest District, has been suc- cessfully enriched by its scientific supervisor – Professor Jerzy Tumiłowicz, the head of the arboretum SGGW in Rogów. Currently, the area of the garden is ap- proximately 8 ha, and the collection amounts to 874 taxa of woody plants – species and varieties of trees and shrubs from various regions of the world are predominant (82.6%). Due to very favourable climatic conditions of the region and favourable microcli- matic conditions of the garden, the collection was enriched by species undergoing frequent freezing in the arboretums in the central and eastern Poland, as well as by those not cultivated in Poland. There are 25 plant species which were introduced to Poland for the first time, mainly from natural sites (Tumiłowicz 2002, 2006). The principle by Tumiłowicz (2009) of cultivating mainly the plants obtained from natu- ral sites with minimum share of widely available cultivars (Kubus 2008) is still respected. Under the cultivation conditions, the acclimatization of plants was suc- cessful for China-fir Cunninghamia lanceolata , giant sequoia Sequoiadendron gi- ganteum and for some rarely grown, very early or very late flowering woody plants of seasonal rhythm which does not coincide with phenological seasons in a year (Kubus 2013, Kubus and Nowak 2013, Nowak et al. 2015). Asian species constitute 56% of the collection (including 180 species of taxa from China), the North Ameri- can species amount to 25% and European 18% (Tumiłowicz 2010). Especially nu- merous are the species of the following genera: maple (68 taxa) and magnolia (24 taxa). The aim of the paper is the characteristic of thermal conditions in arboretum in Glinna, based on the two-year long air temperature measurement series taken at 200 cm a.g.l, and subsequent assessment of the conditions in comparison to data ob- tained from 5 other stations located within, or at the boundary of the Szczecin Coastal Region. It should be noted, however, that the present study is the first re- search on thermal conditions occurring in the arboretum, based on the actual meas- urement data. MATERIALS AND METHODS The Dendrological Garden in Glinna is located on the south-edge of the Bukowa Forest at the height of 51-68 a.s.l., in the lower part of the so-called Sunny Structural Basin. According to the physico-geographical regionalisation by Kondracki (2013), Thermal specification of the Dendrological Garden... 39 the area is located in the mesoregion of the Szczecin Coastal Region, in the microre- gion of the Bukowe Hills – Fig. 1. Additionally, according to the climatic regionali- sation by Koźmiński et al. (2012), the area of Glinna is situated in VI land – Pyrzy- cko-Goleniowska. Mean annual air temperature for this region ranges from 8 to 8.5°C. The last instance of spring frosts at 200 cm a.g.l. is usually observed before 25-30 of April. The dates of the first occurrence of autumn frosts are between 17 and 25 of October. The vegetation period in this region lasts, on average, 222 to 225 days. Fig. 1. Localization of Dendrological Garden in Glinna and measuring stations on the Szcze- cin Coastal Region The present paper is, most of all, an attempt to compare the thermal conditions of the Dendrological Garden in Glinna with the results from other stations located in the area, or in the close vicinity of the Szczecin Coastal Region (the case of Ko- łobrzeg station) – Fig. 1. The meteorological stations in Glinna, Lipnik and Ostoja operate within the measurement network of the West Pomeranian University of Technology in Szczecin, and the stations located in Szczecin, Świnoujście and Ko- łobrzeg are administered by the Institute of Meteorology and Water Management (IMGW). The automatic meteorological station in the Glinna garden was installed in the sec- ond half of 2014. The starting date was the determinant of the period in which the 40 Jadwiga Nidzgorska-Lencewicz, Agnieszka Mąkosza, Marcin Kubus, Grzegorz Nowak analysis was conducted, that is the period of two years – from May 2014 to April 2016. To achieve its objectives, the study uses the hourly values of air temperature taken at 2 m a.g.l. in the aforementioned stations. The obtained results are presented using the basic statistical characteristics. Statistical significance of the difference between the thermal conditions in Glinna and the remaining stations was evaluated with the T-Student test at α = 0.05. Taking into consideration the potential threat to the plants, the dates of the beginning, ending as well as intensity of frosts were established together with the number of days with frost and cold days. There are various defini- tions of frost in the literature on the subject, yet the present paper adopts the defi- nition as given by the meteorological dictionary (Słownik meteorologiczny 2003) which identifies day with frost as the day with a minimum temperature below 0.0°C and a maximum temperature above 0.0°C (t min < 0.0°C, t max > 0.0°C). The cold day is defined as the day with a maximum temperature between 0.0°C to -10°C (t max < 0.0°C to -10°C) – Kossowska-Cezak (2014). RESULTS AND DISCUSSIONS In the period from May 2014 to April 2016, the mean air temperature in Glinna amounted to 10.2°C and was higher by 0.1°C-1.3°C than that recorded in the other stations under analysis – Fig. 2. In turn, the mean maximum air temperature in a 24- hour period in Glinna was 14.1°C, and was lower by 0.5°C only in comparison with Szczecin and higher for all other stations – Lipnik and Kołobrzeg by as much as 1.1°C. The mean minimum air temperature in a 24-hour period in Glinna (6.5°C) was markedly higher than that recorded in the stations located in the closest vicinity (Lipnik, Ostoja, Szczecin), and comparable with the coastal stations. It is worth not- ing that the minimum temperature, as compared with the maximum temperature, was characterised by a significantly greater variability from one 24-hour period to another, yet in Glinna the variability was relatively small and similar to Świnoujście and Kołobrzeg. Fig.