Long-Term Growth Trends Analysis Of Norway Spruce Stands In Relation To Possible Climate Change: Case Study Of Leningrad Region

The Lisino training and experimental forest of the Saint-Petersburg State Forest Technical University was chosen as a study area. The forest is located in the central part of the Leningrad region and has a high level of protection as a forest of scientific and historical value. According to the official data, mean annual temperature in the region increased by 0.6 degrees C within 10 years as well as precipitation. The impact determination of changing climate conditions on Norway spruce trees growth was the aim of this study. Three most representative compartments dominated by Norway spruce (Picea abies (L.) Karst.) were selected for data collection. Core samples were taken by the Pressler increment borer from 107 dominant trees while climatic data were obtained from the nearest weather stations. Tree rings were measured and analyzed using WinDendro software while climate data were processed by Microsoft Excel. Tree ring data cover the time interval from 1848 to 2011, each ring was characterized by width, calendar year, age and diameter of the tree. Radial growth was analyzed within age and diameter classes. Annual rings widths were varied from 0.1 to 6 mm. There was a positive trend in age classes of 0-20, 21-40 and 41-60 years old. The growth was very slow in the age classes of 61-80, 81-100 and >100. Diameters are larger in the age classes of 20-40 and 41-60 as compare to the local diameter growth table which was developed in the 19th century. Diameters for age classes older than 41-60 years were less than prescribed by the diameter growth table. Annual rings width for all age classes also demonstrate cyclic dynamics, moreover, the decline in growth sometimes occurred in recent decades. Multiple regression was used for developing the response function of growth to changes in climatic conditions. There was revealed a high correlation (90 %) and low influence of vegetation period climate data on growth during 1848-2011 (0.08102 mm/degrees C and 0.00085 mm/mm). Likewise, analysis shows that growth is higher in young and middle-aged than mature and over mature stands. Overall, climate change impact has a positive effect on the radial growth of Norway spruce for the studied area, however, not for all age and diameter classes.