Abiotinio streso įtaka aerozolio dalelių masės spektrui miško aplinkoje Lietuvoje

Abiotinio streso veikiami medžiai išskiria lakius organinius junginius (LOJ), kurie yra antrinių aerozolio dalelių (SOA) prekursoriai. Tyrimo tikslas buvo atlikti submikroninių aerozolio dalelių (PM1) masės koncentracijos tyrimus ir šaltinių kilmės atskyrimą medžių abiotinio streso sąlygomis formuojantis SOA. Aerozolio cheminė sudėtis Aukštaitijos integruotoje monitoringo stotyje (IMS LT01) rytinėje Lietuvos dalyje mišraus miško aplinkoje buvo išmatuota aerozolio cheminės sudėties monitoriumi (ACSM). Nustatyta, kad PM1 organikos frakcija sudaryta iš antrinių (76 %) ir pirminių (24 %) aerozolio dalelių. Medžio kamieno skersmens pokyčių analizė parodė tris medžio kamieno skersmens augimo ir susitraukimo epizodus. Esant abiotinio streso sąlygoms, vyksta medžių kamienų skersmens susitraukimo epizodai, todėl išauga m/z 42, 43, 45, 48 ir 50 signalų intensyvumai nuo 5,7 iki 8,8 kartų, o SOA paros koncentracija padidėja nuo 2,7 iki 4,7 kartų. Įprastai augant medžio kamieno skersmeniui m/z signalų intensyvumai ir SOA koncentracija nekinta. Galima teigti, kad augalų patiriamo abiotinio streso atsakas gali būti identifikuojamas per nustatytų m/z signalų intensyvumų pokyčius ir lemti padidėjusią SOA koncentracijąVolatile organic compounds (VOCs) emitted by trees in response to abiotic stress evoke high levels of secondary organic aerosol (SOA) compounds. Few techniques exist to provide chemically-resolved submicron (PM1) particle mass concentrations and source apportionment of stress-induced emissions from trees and SOA formation. The chemical composition of atmospheric aerosol particles was characterized using an aerosol chemical speciation monitor (ACSM) at a mixed-mature forest site – the Aukštaitija Integrated Monitoring Station in the eastern part of Lithuania. The organic fraction of PM1 consisted of SOA (76%) and of anthropogenic combustion related primary organic aerosol (POA) (24%). The analysis of tree trunk circumference revealed three shrinkage and three normal increase episodes. During the episodes of tree trunk circumference shrinkage, several m/z signal (m/z 42, 43, 45, 48, 50) intensities were found to be magnified together with the daily SOA concentration. The stress response analysis confirm that tree trunk circumference shrinkage may be observed through the enhancement of selected m/z signals and result in increased SOA levelsFizinių ir technologijos mokslų centrasMiškų ir ekologijos fakultetasVytauto Didžiojo universitetasŽemės ūkio akademij

Comparative analyses of gas exchange characteristics and chlorophyll fluorescence of three dominant tree species during the vegetation season in hemi-boreal zone, Lithuania

Current climate scenarios predict rising air temperature along with increasing frequency and intensity of summer drought in the Central and Eastern Europe. Severe drought episodes affect physiological processes in trees such as transpiration, photosynthesis and carbon allocation. Understanding gas exchange between plants and the atmosphere is important in woody plant research. The aim of this study was to evaluate differences in gas exchange characteristics and chlorophyll fluorescence of tree species prevailing in Lithuania Scots pine, Norway spruce and Silver birch and their physiological response to water stress. The study was conducted in Aukstaitija integrated monitoring station, Lithuania. Gas exchange parameters and chlorophyll fluorescence were measured during the vegetation season of 2016. Meteorological parameters were obtained from the monitoring station. Four weather periods with different meteorological conditions were identified. Under moderate drought conditions all investigated tree species demonstrated reduced photosynthetic rates, lower stomatal conduction transpiration rates, water use efficiency and instantaneous carboxylation efficiency. During moderate drought, intercellular CO2 concentration of Norway spruce was higher and this species demonstrated the highest decrease in instantaneous carboxylation efficiency. No significant changes of maximal chlorophyll fluorescence Fv/Fm among species were detected during different weather periods except Silver birch. The investigated tree species reacted differently to weather conditions. The Scots pine demonstrated the highest tolerance to different weather conditions. The study confirmed the sensitivity of Norway spruce to drought conditions. The Silver birch was the least sensitive to temperature and humidity conditions variationFizinių ir technologijos mokslų centrasMiškų ir ekologijos fakultetasVytauto Didžiojo universiteta

Ecophysiological reactions of prevailing in Lithuania tree species to meteorology and air pollution

Fizinių ir technologijos mokslų centrasVytauto Didžiojo universitetasŽemės ūkio akademij

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;[...]Aplinkos tyrimų centrasFizinių ir technologijos mokslų centras, VilniusVytauto Didžiojo universitetasŽemės ūkio akademij