Fire Occurrence in Hemi-Boreal Forests: Exploring Natural and Cultural Scots Pine Fire Regimes Using Dendrochronology in Lithuania

Fire is an important natural disturbance and a driver of hemi-boreal forest successional trajectories, structural complexity, and biodiversity. Understanding the historic fire regime is an important step towards sustainable forest management. Focusing on Lithuania's hemi-boreal forests, we first mapped the potential natural fire regimes based on the relationship between site conditions, vegetation, and fire frequency using the ASIO model. The ASIO model revealed that all the fire frequency categories (Absent, Seldom, Intermittent, Often) are found in Lithuania. Scots pine forests dominated the often fire frequency category (92%). Secondly, focusing on a fire-prone forest landscape, Dzukija, we analyzed the fire occurrence of Scots pine forest types using dendrochronological records. We sampled and cross-dated 132 Scots pine samples with fire scars from four dry forest stands (n = 92) and four peatland forest stands (n = 40), respectively. In total, the fire history analysis revealed 455 fire scars and 213 fire events during the period of 1742-2019. The Weibull median fire intervals were 2.7 years (range 1-34) for the dry forest types and 6.3 years (range 1-27) for the peatland forest types. Analysis pre- and post-1950 showed the Weibull median fire interval increased from 2.2 to 7.2 for the dry forest types but decreased from 6.2 to 5.2. for the peatland forest types. A superposed epoch analysis revealed significant precipitation fluxes prior to the fire events after 1950. Thus, the Dzukija landscape of Lithuania has been strongly shaped by both human and naturally induced fires. The combination of theory (the ASIO model) with the examination of biological archives can be used to help guide sustainable forest management to emulate forest disturbances related to fire. As traditional forest management focusing on wood production has eliminated fire, and effectively simplified forest ecosystems, we recommend introducing educational programs to communicate the benefits and history of forest fires as well as adaptive management trials that use low-intensity prescribed burning of Scots pine stands

Mixing effects on Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) productivity along a climatic gradient across Europe

Mixed-species stands have been found to be more productive than would be expected from the performance of their component species in monocultures due to facilitation and complementarity between species, although these interactions depend on the combination of species present. Our study focuses on monospecific and mixed species stands of Scots pine and Norway spruce using 20 triplets established in nine countries along a climatic gradient across Europe. Differences in mean tree and stand characteristics, productivity and stand structure were assessed. Basal area increment in mixed stands was 8% higher than expected while volume increment was only 2% greater. Scots pine trees growing in mixed-species stands showed 11% larger quadratic mean diameter, 7% larger dominant diameter, 17% higher basal area and 25% higher stand volume than trees growing in mono specific stands. Norway spruce showed only a non-significant tendency to lower mean values of diameters, heights, basal area, as well standing volume in mixtures than monocultures. Stand structure indices differed between mixed stands and monocultures of Scots pine showing a greater stratification in mixed-species stands. Furthermore, the studied morphological traits showed little variability for trees growing in monospecific stands, except for diameter at breast height, crown length and crown length ratio. For trees growing in mixed stands, all the morphological traits of the trees were identified as different. Some of these morphological traits were associated with relative productivity. Nevertheless, relative productivity in mixed-species stands was not related to site conditions

Forest biodiversity, carbon sequestration, and wood production: modeling synergies and trade-offs for ten forest landscapes across Europe

Original ResearchEurope’s forests provide vital habitat for biodiversity and essential ecosystem services whose provision must be sustained or enhanced over the coming century. However, the potential to secure or increase forest ecosystem services, while securing the habitat requirements of taxa remains unclear, especially within the context of uncertain climate and socio-economic developments. To tease out the associated trade-offs and synergies, we used 10 case study landscapes within nine countries throughout Europe. Starting with the current status of the forests in the case study landscapes, we simulated forest development 100 years into the future. Simulations were embedded in three combined climate and socio-economic frame scenarios based on global and European policies which varied in their climate change mitigation efficiency. Scenarios were translated into country specific projections of climate variables, and resultant demands for wood products. Forest management regimes were projected to vary in response to these scenarios at local scales. The specific combinations of alternative forest management practices were based on parallel research and input from local forest stakeholders. For each case study, a specific forest growth simulator was used. In general, the climate scenarios applied did not cause fundamentally different ecosystem service outputs at the case study level. Our results revealed almost no reduction in outcomes for biodiversity indicators with an increase in wood production, and in some cases synergistic results occurred when diversity was actively promoted as part of the management concept. Net carbon uptake was not strongly correlated with biodiversity, indicating that biodiversity-friendly forest management doesn’t need to curtail carbon sequestration. Notably, we obtained heterogeneous results for the relation between sustainable wood production and net carbon uptake. Most scenarios resulted in a more or less reduced net carbon uptake over the long term, often due to stand age class distribution shifts. Levels of sustainable wood production varied widely during the simulation period, from significant increases (Sweden, Lithuania) to minor changes (Slovakia, Turkey) and slight decreases (Ireland, Netherlands). We place our results within the larger context of European forest policy and the challenges of simulating and contrasting forest biodiversity and the ecosystem services that societies depend on outcomes for biodiversity indicators with an increase in wood production, and in some cases synergistic results occurred when diversity was actively promoted as part of the management concept. Net carbon uptake was not strongly correlated with biodiversity, indicating that biodiversity-friendly forest management doesn’t need to curtail carbon sequestration. Notably, we obtained heterogeneous results for the relation between sustainable wood production and net carbon uptake. Most scenarios resulted in a more or less reduced net carbon uptake over the long term, often due to stand age class distribution shifts. Levels of sustainable wood production varied widely during the simulation period, from significant increases (Sweden, Lithuania) to minor changes (Slovakia, Turkey) and slight decreases (Ireland, Netherlands). We place our results within the larger context of European forest policy and the challenges of simulating and contrasting forest biodiversity and the ecosystem services that societies depend oninfo:eu-repo/semantics/publishedVersio

Environmental and genetic attributes of wolf trees’ morphological types in Scots pine (Pinus sylvestris L.)

Šioje disertacijoje mes išskyrėme du paprastosios pušies medžių-vilkų morfotipus. Naudojant aplinkos ir palikuonių analizės, dendrochronologijos ir genetikos metodus mes nustatėme paprastosios pušies medžių-vilkų augimo ypatumus. Tai leido nustatyti ženklius genetinius ir ekologinius skirtumus tarp medžių-vilkų ir kitų augimo klasių medžių bei tarp dvejų medžių-vilkų morfotipų. Mūsų tyrimai atskleidė, kad abu medžių-vilkų morfotipai genetiškai skyrėsi nuo eilinių paprastosios pušies medžių, kas nulėmė statistiškai patikimus skirtumus tarp medžių-vilkų ir eilinių medžių reakcijų dirvožemio derlingumui ir mezoreljefui. Palyginus medžių-vilkų ir eilinių medžių vidutinius metinius radialiuosius prieaugius, greitesnis medžių-vilkų augimas pastebėtas iki 35 metų. Jautrumas aplinkos veiksniams stipriai priklausė nuo medžių-vilkų morfotipo. Antrojo morfotipo medžiai-vilkai buvo jautresni kritulių kiekiui, o eiliniai medžiai ir pirmojo morfotipo medžiai-vilkai – oro temperatūrai. Palikuonių analizė atskleidė, kad jau nuo pirmų augimo metų medžių-vilkų palikuonys turėjo ilgesnius šoninius ūglius ir didesnį šoninių ūglių kiekį, o eilinių medžių palikuonys suformavo didesnį aukščio prieaugį.In this thesis we approved the existence of two wolf trees‘ morphological types in Scots pine (Pinus sylvestris L.). With the use of environmental and progeny analysis, dendrochronology and genetic methods we assessed the wolf trees in Scots pine from several points of view. This allowed us to find out the differences both between the regular trees and wolf trees and between the two wolf trees‘ morphological types. Both morphological types were genetically different from the regular Scots pine trees, what resulted in significant differences between the two wolf tree morphological types and the regular trees in their responses to soil fertility and mezorelief. Comparing the annual increments of wolf trees and regular trees, we could observe faster growth of the wolf trees up to the age of 35 years. Sensitivity to the climatic factors strongly depended on the wolf tree morphological type. The second morphological type exhibited a stronger response to precipitation, while the control trees and the first wolf tree morphological type had stronger responses to temperature. Progeny analysis showed that as early as the first year of growth, the wolf tree progenies had longer branches and a higher branch number, while the progenies of the regular trees had bigger height increment.Žemės ūkio akademijaVytauto Didžiojo universiteta

Environmental and genetic attributes of wolf trees’ morphological types in Scots pine (Pinus sylvestris L.)

Šioje disertacijoje mes išskyrėme du paprastosios pušies medžių-vilkų morfotipus. Naudojant aplinkos ir palikuonių analizės, dendrochronologijos ir genetikos metodus mes nustatėme paprastosios pušies medžių-vilkų augimo ypatumus. Tai leido nustatyti ženklius genetinius ir ekologinius skirtumus tarp medžių-vilkų ir kitų augimo klasių medžių bei tarp dvejų medžių-vilkų morfotipų. Mūsų tyrimai atskleidė, kad abu medžių-vilkų morfotipai genetiškai skyrėsi nuo eilinių paprastosios pušies medžių, kas nulėmė statistiškai patikimus skirtumus tarp medžių-vilkų ir eilinių medžių reakcijų dirvožemio derlingumui ir mezoreljefui. Palyginus medžių-vilkų ir eilinių medžių vidutinius metinius radialiuosiusprieaugius, greitesnis medžių-vilkų augimas pastebėtas iki 35 metų. Jautrumas aplinkos veiksniams stipriai priklausė nuo medžių-vilkų morfotipo. Antrojo morfotipo medžiai-vilkai buvo jautresni kritulių kiekiui, o eiliniai medžiai ir pirmojo morfotipo medžiai-vilkai – oro temperatūrai. Palikuonių analizė atskleidė, kad jau nuo pirmų augimo metų medžių-vilkų palikuonys turėjo ilgesnius šoninius ūglius ir didesnį šoninių ūglių kiekį, o eilinių medžių palikuonys suformavo didesnį aukščio prieaugį.In this thesis we approved the existence of two wolf trees‘ morphological types in Scots pine (Pinus sylvestris L.). With the use of environmental and progeny analysis, dendrochronology and genetic methods we assessed the wolf trees in Scots pine from several points of view. This allowed us to find out the differences both between the regular trees and wolf trees and between the two wolf trees‘ morphological types. Both morphological types were genetically different from the regular Scots pine trees, what resulted in significant differences between the two wolf tree morphological types and the regular trees in their responses to soil fertility and mezorelief. Comparing the annual increments of wolf trees and regular trees, we could observe faster growth of the wolf trees up to the age of 35 years. Sensitivity to the climatic factors strongly depended on the wolf tree morphological type. The second morphological type exhibited a stronger response to precipitation, while the control trees and the first wolf tree morphological type had stronger responses to temperature. Progeny analysis showed that as early as the first year of growth, the wolf tree progenies had longer branches and a higher branch number, while the progenies of the regular trees had bigger height increment.Žemės ūkio akademijaVytauto Didžiojo universiteta

IUFRO kongrese Freiburge

Vytauto Didžiojo universitetasŽemės ūkio akademij

Paprastosios pušies medžiai vilkai: aplinkos ir genetinis sąlygotumas

Vytauto Didžiojo universitetasŽemės ūkio akademij

Scots pine (pinus sylvestris l.) wolf trees: morphotypes and growth patterns

Vytauto Didžiojo universitetasŽemės ūkio akademij

Scots pine wolf trees: environmental and genetic conditionality

Vytauto Didžiojo universitetasŽemės ūkio akademij

Išnaudokime galimybes plėsti papildomą veiklą

Miškų ir ekologijos fakultetasVytauto Didžiojo universiteta