Scots pine tree ring structure modifications and relation with climate

Eurasscience Journals Eurasian Journal of Forest Science (2016) 4(2): 1-7 SCOTS PINE TREE RING STRUCTURE MODIFICATIONS AND RELATION WITH CLIMATE Anca I. SEMENIUC1,, Cristian G. SIDOR1, Ionel POPA1,2 1National Research and Development Institute for Silviculture / Forest Research Station Câmpulung Moldovenesc, Calea Bucovinei 73bis, Ro725100, Romania email: 2Stefan cel Mare University of Suceava / Forestry Faculty, 13 Universității, Suceava, Romania Abstract In this study we assessed the tree ring structure modifications and the relation with climate in Scots pine from Aleșd region (Romania). Tree rings structures were analysed based on microscopic sections obtained from the core sample. The analysis on the area of the incomplete lignified cells (IC) and the lignified cells (CL) was made. The results show a high frequency of false rings, and unlignified cells. The tree ring with the highest unlignified cells part could be observed in the years 2007 and 1989. A reduced number of the unlignified cells were formed in the year 1998. An anomaly was analyzed in the tree ring structure of the year 1986. The temperature below 10 °C in the second period of the growing season has stopped the process of lignification of the wood cell walls. This study confirms the influence of temperature on the formation of the Scots pine tree rings. Key words: Scots pine, anatomical structure, radial growth, tree rings, temperature. Özet Bu çalışmada Aleşd (Romanya) bölgesinde bulunan sarıçam bireylerinde yıllık halka yapılarındaki değişimler ve bunun iklim bileşeniyle olan ilişkisi incelenmiştir. Ağaçların yıllık halka yapıları, ağacın özünden alınan mikroskobik kesitler üzerinden analiz edilmiştir. İncelenen kesitlerdeki tamamlanmamış odunlaşmış hücreler ve odunlaşmış hücreler analiz edilmiştir. Sonuçlar, yalancı halkaların ve odunlaşmamış hücrelerin çok sık olduğunu göstermiştir. En yüksek odunlaşmamış hücreye sahip yıllık halkalar 2007 ve 1989 yıllarında gözlemlenmiştir. Odunlaşmamış hücreli yıllık halkaların 1998 yılında daha az olduğu tespit edilmiştir. Anormal hücrelerin bulunduğu yıllık halkaların 1986 yılında daha fazla olduğu görülmüştür. Büyüme döneminin ikinci yarısında gerçekleşen 10 oC’nin altındaki sıcaklıklardan dolayı, odun hücre duvarlarının gelişimini durdurmuştur. Bu çalışma, sarıçamlarda sıcaklığın yıllık halka oluşumunu engellediğini onaylamaktadır. Anahtar kelimeler: Sarıçam, anatomik yapı, ışınsal büyüme, yıllık halkalar, sıcaklık. INTRODUCTION The evolution of radial growth stages throughout the growing season is reflected ultimately in the anatomical structure of the tree ring. The tree ring structure is the outcome of interactions between the processes of growth and environmental factors. Detailed anatomical analyses have described the correct course of xylogenesis during a year (Rossi et al. 2006, Rossi et al. 2008, Deslauriers et al. 2008). The tree ring growth is controlled by external factors but also by internal factors. Thus, the physiological processes are important in the wood’s cells 1 Scots Pine Tree Ring Structure Modifications – Semeniuc et al. 4(2):1-7 (2016) development (Denne and Dodd 1981, Schweingruber 1992, Kozlowsky and Pallardy 1997, Larcher 2003). The climatic factor, mainly the temperature has an important influence on anatomical structure of the ring. The process of the wall cells formation is restricted by the climatic factor reflected in the final structure of the tree ring (Schweingruber et al. 1990, Vaganov et al. 1996, Vaganov et al. 2006, Piermattei et al. 2014). Temperature induced stress is argued on long period into the structure of the tree rings (Camarero et al. 1998, Wimmer et al. 2000, Gindl et al. 2001, Schmitt et al. 2003, Camarero et al. 2010). The impact of drought and temperature on the formation of the tree rings at Scots pine has been analyzed in many studies (Antonova and Stanova 1993, Oberhuber et al. 1998, Gruber et al. 2010, Ziaco et al. 2014, Pacheco et al. 2016). A response of radial growth effect may be given by the species inadaptability to climate changes (Thompson 1998). The effect of heating and cooling in the development of the cells was analyzed in a forest of Ljubljana (Gričar et al. 2006). The radial growth slowdown is reflected in the formation of the false rings influencing the tree ring width (Hoffer et al. 2009, Marchand and Filion 2012). Donaldson (2002) studied the anormal deposition of lignin in the cells walls of Pinus radiata in the dry period. The drying of the Scots pine meant a good indicator in starting our study in order to assess the structure of tree rings and discover the factors involved in the process of radial growth. MATERIAL AND METHOD The study area is located in the Western Carpathians, Aleșd area (47°00'N latitude and 22°23' E longitude) and at about 500 m altitude (Figure 1). The annual mean air temperature is 10.5°C and the annual level of precipitation 635 mm. The trees in the studied area show sign of mortality with a low, moderate and strong intensity. To analyze the impact of climatic factor with negative effect on radial growth were been extracted core samples from Scots pine trees without visible defects on the surface of the trunk. The samples for analysis were processed and analyzed in the laboratory Figure. 1 The map with the location of Scots pine in Aleșd (Google Earth source). according to the studies (Gärtner and Schweingruber 2013, Piermattei et al. 2014). The core with a length of about 15 cm was cut into five equal pieces. With the microtome type GSL1, were obtained 10-15 µm microsections. These samples were colored with astra blue dye (1 g/200 ml distilled water) mixed with safranin-dye (2 g/200 ml distilled water) to distinguish the lignified cells from the unlignified ones. Finally, for preservation, the microscopic sections were permanently fixed with Canada balsam. After completing the procedures, all microscopic sections were analyzed with the Axio Imager A1m Zeiss microscope and stereomicroscope. The evaluation of anatomical structure was made on the entire length of the core starting from the bark up to the pith. The analysis on the annual ring growth was done on each ring, both the lignified cells (CL) and the area of the incomplete lignified cells (IC). The lignified cells are completely colored in red and unlignified cells is in blue. The area with incomplete lignified cells was identified after the blue color in the wall cells (Rossi et al. 2006, Piermattei et al. 2014). Other observations have been made at false rings made up of small-sized cells colored in red (Marchand and Filion 2012). The cells with thick walls and small size found in the inside of the ring form the false annual ring (FR). Observations were made on the whole surface of the ring analyzing the tree ring structure. The climate data were obtained from the meteorological station located in the Aleșd area. 2 Eurasian Journal of Forest Science 4(2):1-7 (2016) RESULTS AND DISSCU (...truncated)