Adomas Vitas

Dynamic response of tree growth to changing environmental pollution

Long-term investigations of Scots pine (Pinus sylvestris L.) growth were carried out in the vicinity of one of the biggest air pollution sources in Lithuania—mineral fertilizers plant “Achema.” It is detected that initial stages of the dynamic tree response to the external stress factors in the polluted environment with an increased quantity of nitrogen compounds have started with a stimulation stage, followed by a gradual transition to a depression of growth. The recovery of the damaged stands took place along with the reduced environmental pollution, and the overdraft of the “normal” annual increment was a characteristic feature of all the investigated stands. This phase is still continuing for the most damaged stands. A very high individual variability of the tree growth response to the environmental impact is a characteristic feature of the damaged Scots pine stands. The homeostatic mechanisms of the survived trees stipulated reaching approximately the same or even higher growth rate as prior to the depression period, and the tree growth rate before the depression period can serve as the most powerful predictor of tree growth recovery capacity under the reduced environmental pollution. Crown defoliation is the next most important predictor of individual tree recovery capacity. Lower stand density and lower competition cause higher recovery capacity of damaged trees. The conclusion is made that a reduction in the environmental pollution on the local and regional scale and especially a decrease in emissions and deposition of sulfur and nitrogen compounds caused the recovery of damaged forests. These trends should be taken into account while analyzing and modeling forest dynamics. Interaction of environmental pollution and climatic factors is very important for the response of tree growth to the environmental stressors.

Did the Ambient Ozone Affect Stem Increment of Scots Pines (Pinus sylvestris L.) on Territories under Regional Pollution Load? Step III of Lithuanian Studies

This study aimed to explore if changes in stem increment of Scots pines (Pinus sylvestris L.) could be related to changes in ambient ozone concentration when the impact of tree dendrometric parameters (age, diameter) and crown defoliation are accounted for. More than 200 dominant and codominant trees from 12 pine stands, for which crown defoliation had been assessed since 1994, were chosen for increment boring and basal area increment computing. Stands are located in Lithuanian national parks, where since 1994–95 Integrated Monitoring Stations have been operating. Findings of the study provide statistical evidence that peak concentrations of ambient ozone (O3) can have a negative impact on pine tree stem growth under field conditions where O3 exposure is below phytotoxic levels.

Tree-ring formation as an indicator of forest capacity to adapt to the main threats of environmental changes in Lithuania

Global changes occurring under different environmental conditions have changed stand competition, as well as nutrient and light availability, which has resulted in changes in productivity. Therefore, in the present study, the characteristics of tree-ring width formation of the prevailing Lithuanian tree species, Norway spruce, Scots pine and silver and downy birch, and key factors resulting in their differences during the last 36-year period were investigated at forest sites located on poor mineral oligotrophic and on nutrient-rich organic mesoeutrophic soils. The aim of the study was as follows: first, to separately detect the maximum possible seasonal effect of three groups of variables - meteorology, acidifying pollutants and surface ozone on the stem basal area increment (BAI) of the evaluated tree species; second, to assess the significance of each group of variables affecting the BAI of these tree species integrally with the remaining groups of variables. Norway spruce was found to be well adapted to recent environmental changes, which makes it one of the most favourable tree species for silviculture in the northeastern part of Europe. The rapid increases recorded in growth intensity since 1980 were attributed to the increase in air temperature, precipitation amount, nitrogen deposition during the vegetative stage and reductions in SO2 concentrations and S deposition. Scots pine demonstrated the highest level of resilience and capacity to adapt to recent global changes because its reaction to both negative and favourable environmental factors was best expressed. Silver and downy birch tree reactions to the effects of air concentrations of acidifying compounds, their deposition and surface ozone concentrations were the least expressed; however, a significant decline in growth intensity indicated that these tree species experienced a reduced resistance to recent changes in environmental conditions in the mature and over-mature age groups.

Growth/Climate Relationships in Tree-Ring Widths of Picea Abies in Lithuania and Poland

The main aim of this study is to generalise the climate – growth response of spruce on the selected sites in natural stands of Poland and Lithuania where climatic conditions and biogeographical differences are expressed in terms of the influences of oceanic and continental climates. For this purpose almost 2,000 cores were taken from 92 sites (10–30 trees per site, two cores per tree). Hierarchical cluster analysis (HCA) was used to distinguish regions with similar increment patterns. Climate-growth relationships were calculated by means of the PRECON program (Fritts 1996). We were able to recognize four main groups where linkage distance is higher than 2 (Figs. 14.1 and 14.2). Tree-ring-widths from three regions (1a, 1b, 2a) are mostly determined by precipitation during the vegetation period, especially from May to July (Tables 14.1, 14.2 and 14.3). Trees from the southern part of Poland (region 2b) are more sensitive to March temperature (Table 14.4).The decrease in dominance of the Atlantic climate from the south to the northeast is also responsible for distinguishing regions 2a and 2b.

Climatically induced light rings of European larch ( Larix decidua Mill.) in Lithuania

Key messageUnfavourable climatic conditions trigger the formation of the light rings of European larch in Lithuania.AbstractThe spatiotemporal analysis of European larch light rings in Lithuania was investigated to discover the spatial variability of light-ring formation and determine the climatic factors that trigger their formation. For this purpose, a case study in 24 research plots of larch was conducted. European larch light rings in Lithuania are associated with narrower rings than their adjacent rings and a decreased latewood proportion in the tree ring. The study has shown that cold winters do not have a significant negative influence on radial growth of larch in Lithuania. Long-lasting droughts in spring and summer and excessive wet periods in summer, especially in August, are the main climatic drivers inducing the light rings of larch. However, not all light rings could be explained with climatic extremes, suggesting that there are also non-climatic triggers of the light rings in larch.