Intra-Annual Variation of Stem Circumference of Tree Species Prevailing in Hemi-Boreal Forest on Hourly Scale in Relation to Meteorology, Solar Radiation and Surface Ozone Fluxes

Abstract

(1) Background: Continuous monitoring of the tree stem increment throughout the year is crucial for the understanding of trees’ reactions to changes in meteorology, solar radiation and surface ozone and evaluating the adaptive capacity of prevailing tree species to recent environmental global changes; (2) Methods: Data on tree intra-annual sequences based on electronic dendrometer data of Picea abies (L.) Karst, Pinus sylvestris L., Betula pendula, and Betula pubescens, growing under different nutritional and humidity conditions in the north-eastern part of Lithuania, together with their stem sap flow intensity, common meteorology and O3 fluxes, were used to meet the objectives of the study; (3) Results: Stem shrinking/contraction during the day, due to transpiration, and the swelling/expansion during the night was significantly related to meteorology, sun activity and O3 flux intensity. These variations were negatively related to current time and temperature, but positively to precipitation and relative humidity. O3 fluxed through the stomata stimulated the shrinking process more intensively than it inhibited the swelling process, but only for pine and birch trees. Spruce trees demonstrated the highest sensitivity to O3 impact due to its significant effect on the stem swelling process. Pine trees were less sensitive to O3 damages and birch trees were the least sensitive. An over-moisture regime at measoeutrophic organic soil forest site increased the significance of the effect of O3 on the tree increment of the considered tree species; (4) Conclusion: The most intensive tree ring formation of Scots pine trees in relation to recent environmental changes indicated their high resiliencies and adaptations to a local specific condition. Reduced tree growth intensity and weak relationships between the birch tree radios increment and main meteorological parameters indicated the lowest adaptive capacity of this tree species to recent environmental changes.

Transpiration Rate of Scots Pine Trees on Very Oligotrophic Soils of Normal Moisture in Relation to Different Meteorological Condition

“…Its drought sensitivity depends on site related factors especially on relief, topography and soil characteristics such as rooting and water holding capacity of soils (Levesque et al, 2014). Therefore, the reactions of this considered tree species to extreme meteorological events under different growth conditions differed significantly due to their different strategies (McDowell 2008;Augustaitis et al, 2018;Marozas et al, 2019) when surviving first of all heat and drought episodes (Lévesque et al, 2014;Augustaitis 2021) what quite well indicates their needles spectral reflectance (Masaitis et al, 2013(Masaitis et al, , 2014. This finding well agreed with results obtained on annual scale which indicated that meteorology explained variation in annual pine tree ring width variation more significantly than acidifying compounds (Augustaitis et al, 2007b(Augustaitis et al, , 2015(Augustaitis et al, , 2018Juknys et al, 2014).…”

“…Such changes could affect also trees resistance to pest damage (Augustaitis, 2007). Long-term analysis of meteorological data for a gradient from the coastal to eastern inner Lithuania revealed an increase in annual air temperature and precipitation and rising variation in monthly patterns during the period 1981-2020 compared to 1950-1980 (Augustaitis et al, 2018(Augustaitis et al, , 2021. The lack of atmospheric humidity is predicted to reinforce negative effect of climate warming in southern and central parts of Europe, meanwhile in northeastern part of Europe, including Lithuania gradual increase in precipitation amount should mitigate this negative effect of climate changes increasing tree increment (Augustaitis et al, 2015(Augustaitis et al, , 2018.…”

“…Continuous monitoring of tree ring formation throughout the year together with the stem sapflow intensity is crucial for the understanding of tree reaction to changes in environmental conditions, such as temperature, soil water content and rainfall. This investigation can be performed by using sapflow equipment (Baumgarten et al, 2019) and automatic dendrometers (Deslauriers et al, 2007;Augustaitis 2021). These equipments provide time series composed of diurnal rhythms of water storage depletion and replenishment which result in general tree ring formation.…”