Central Latvia Research Articles

Sacred Footwear: Latvian Perceptions in the 19th Century and Today

This article sheds light on previously overlooked perceptions of Latvian traditional footwear and demonstrates how both the material of the footwear and the way of obtaining it determined whether shoes were considered sacred and pure or sinful and unlucky. An analysis of folklore texts and the results of a contemporary survey show that wooden shoes made of bast were looked upon as sacred and pure, as opposed to leather which was considered impure. Bast shoes are the cheapest to make, yet historical records from central Latvia show that they were worn for weddings. Peasants did this to ensure success for the couple, suggesting that the choice of footwear was determined by some mythological meaning and not only by practical or financial considerations. Though some new developments can be observed, many modern Latvians tend to sympathize with the perceptions documented a century ago. This allows for estimates of the significance of these perceptions in previous centuries.

Late Holocene changes in the water table at an alkaline fen in Central Latvia: Their impacts on CaCO3 deposition at the fen and relation to the hydroclimate patterns of the Eastern Baltic Region

Sediments of CaCO3-precipitating alkaline fens, comprising biotic and abiotic indicators of water table changes, are among the most reliable archives for obtaining palaeohydrological data. The study uses a semiquantitative method based on a combination of selected indicators (plant macrofossils, mollusc shells, degree of peat decomposition) to estimate the relative changes in the water table position at Lustūžkalns alkaline fen, Latvia, Eastern Baltic Region. The study also aims to determine the time frames of CaCO3 deposition at the fen using loss on ignition and carbon and oxygen stable isotope records. The chronology of the three sediment sequences studied is based on the AMS radiocarbon dating of terrestrial plant macrofossils. Although the reconstructed water table positions revealed differences between the cores, the major shift from the low water tables persisting since ca. 5000 cal yr BP to the prevailing high water stands at ca. 3000 cal yr BP was common to all the sequences. The major shift observed is consistent with a change from low to high water tables in peatlands in Latvia and at numerous fens and bogs across the Eastern Baltic Region, Fennoscandia and NW Europe. Concurrent with the increase in the water tables was the onset of CaCO3 precipitation on the Lustūžkalns fen surface, which began at ca. 3000 cal yr BP and accelerated from ca. 2500 cal yr BP. The Late Holocene CaCO3 precipitation at Lustūžkalns can be attributed to the change from warm and dry conditions during the Holocene Thermal Maximum (HTM) to cooler but humid during the Late Holocene. In contrast, in Central and Western Europe, the main period of freshwater carbonate precipitation occurred during the warm and humid HTM.

Vegetation response to forest ditch reconstruction: Promoting a potential habitat for insect-pollinated plant species?

Abstract In a managed forest landscape, the high degree of human intervention has caused significant shifts in natural processes, and preservation of remaining natural ecosystem features is crucial to safeguard ecosystem functioning and support ecosystem services. While drainage ditches, subject to regular maintenance, are anthropogenically created and maintained infrastructure elements, they may still support diverse environmental conditions and provide habitats for a variety of plant species, including flowering plants important for pollinators. We assessed vegetation composition changes on recently reconstructed and unmanaged forest ditches and ditch edges in a commercial forest in Central Latvia in two surveys (one and five years after the ditch reconstruction). We used generalized linear mixed-effects models to analyze the impact of environmental variables on species richness and detrended correspondence analysis to analyze plant species composition. We found higher total plant species richness and insect-pollinated plant species richness along recently reconstructed ditches. The differences were mainly explained by better light availability beside reconstructed ditches. Anthropogenically created and managed ecosystems may support biodiversity and directly and indirectly contribute to the provision of different ecosystem services, including pollination.

Anthropogenic impact on a seacoast landscape during the last 1300 years in central Latvia, Northeastern Europe

AbstractHuman‐induced activities around Lake Lilaste in the central Latvian sandy coastal area have been reconstructed over a 1300‐year period. We use a combination of well‐established geoarchaeological research methods (14C dating, pollen, nonpollen palynomorphs, REVEALS modeling, diatoms, C/N ratio, magnetic susceptibility, loss on ignition) to study the human impact on the environment. Historical context aids focus on records of resource (e.g., timber) exploitation in the area. The continuous record of human indicator pollen and agricultural landscape suggests this area was suitable for habitation well before the studied time period, likely due to the ecosystem services it provided. Our proxy‐based study, combined with historical background, reveals a significant human impact on the terrestrial environment since the 14th century. Deficiency of trees in the northern outskirts of Riga during the 17th–19th century was likely. Anthropogenic activity has led to both deforestation and change in species composition. Our paleo records indicate recognizable human‐driven legacy in current seacoast landscape.

Trombe Wall System’s Thermal Energy Output Analysis at a Factory Building

Solar energy utilization for covering and offsetting the heating loads of buildings, is a sustainable way to reduce energy consumption (electricity, gas, etc.) for space heating. As such, a Trombe wall technology is a classic passive solar heating system used in buildings, that can be modified and applied to cold climate regions. This work presents a case study on a Trombe wall’s application in relation to its thermal energy output for space heating purposes at a factory building in central Latvia. The solar radiation and temperature measurements were carried out throughout the months of June to October. The results show that the examined wall has a monthly energy yield of 120 to 290 kWh, suggesting that Trombe wall systems are applicable as a secondary space heating source in cold climate regions such as northern Europe, however, a number of design and structural aspects have to be thoroughly considered.

N2O AND CH4 EMISSIONS FROM NATURALLY WET AND DRAINED NUTRIENT-RICH ORGANIC FOREST SOILS

According to general knowledge rewetting of drained organic soils is a measure that can reduce net greenhouse gas emissions from ecosystem, however there is lack of evidence that approves such an assumption in hemiboreal forests. The aim of the study was to quantify N2O and CH4 flux from nutrient-rich organic soils in naturally wet (NWS) and drained (DS) hemiboreal forest sites in Latvia. In central Latvia, 26 NWS (Dryopterioso–caricosa and Filipendulosa) and DS (Oxalidosa turf. mel.) were selected to evaluate annual N2O and CH4 soil flux by manual chamber method. Gas sampling was performed once a month in five replicates in every sampling plot for period of one year covering all seasons from October of 2019 till November of 2020. During gas sampling soil temperature and groundwater level were measured. In addition, soil and groundwater was sampled and tested. Study results show that soil CH4 flux has strong correlation with groundwater level and weak correlation with soil temperature in booth DS and NWS. Moderate correlation between soil temperature and N2O flux were found in DS, however in rest of the study sites significant impact of soil temperature and groundwater level on N2O flux was not found. Estimated annual average soil CH4 flux is average ‑3.5±1.0 kg C‑CH4 ha-1 yr-1 in DS and average 100.6±101.0 kg C‑CH4 ha-1 yr-1 in NWS. While estimated annual average soil N2O flux is average 1.1±0.4 kg N‑N2O ha‑1 yr-1 in DS and 2.6±0.9 kg N‑N2O ha-1 yr-1 in NWS.

Early and early Middle Ordovician chitinozoans from the Baldone drill core, central Latvia

Early and early Middle Ordovician chitinozoans from the Baldone drill core, central Latvia

Sedimentary environments and stratigraphy of the Stipinai Formation (Upper Frasnian, northern Lithuania): a sedimentary record of sea-level changes in the Main Devonian Field of the East European Platform

The Frasnian carbonate-siliciclastic deposits of the Stipinai Formation exposed in two quarries at Petrašiūnai and Klovainiai (northern Lithuania) show considerable vertical facies changes. The lower part of this succession is dominated by argillaceous dolomitic facies with subordinate fine siliciclastic deposits. They display haloturbation and bioturbation structures, represent a hypersaline lagoonal environment, and record the beginning of the transgression. The middle part of the succession consists of secondary dolostones containing moulds of brachiopods, tetracorals, stromatoporoids and trace fossils of deposit feeders; these were deposited in a shallow subtidal marine environment and represent the deepest sedimentary environment of this succession. This was followed by a lagoonal environment (episodic hypersaline), represented by dolomudstones and marly dolomudstones. The upper part of the succession is built of bedded dolostones which document a shallowing trend. Intercalations of clays and palaeosol horizons record emergence events. Palynostratigraphic data tentatively indicate that the Stipinai Formation represents the Upper Frasnian. The succession can be interpreted as a record of the upper part of a T-R cycle (related to the semichatovae transgression) in the Main Devonian Field of the East European Platform. The Stipinai Formation is distributed across western and central Latvia and has a correlative in the Pomerania Basin (northern Poland).

Fire frequency during the Holocene in central Latvia, northeastern Europe

Fire frequency during the Holocene in central Latvia, northeastern Europe

The Raunis section, central Latvia, revisited: first luminescence results and re-evaluation of a key Baltic States stratigraphic site

ABSTRACT In interstadial deposits, sand interbeds gain limited consideration in comparison with organic sediments, and therefore tend to be underrepresented in paleoenvironmental reconstructions. The Raunis site, central-eastern Latvia, is an example where organic beds have already gained some attention and been used to understand the complex interactions between advance and retreat of the Scandinavian Ice Sheet in the region. Sandy interlayers have so far not been investigated in detail and their time of deposition has also been unknown, therefore exploring these clastic-organic sediment alternation is of interest. This study provides a new set of luminescence datings along with sedimentological information from the character of individual quartz grains as detected from scanning electron microscope analysis. Sandy interlayers are dated to between 12 and 122 ka. Fast component OSL signal dominates in all investigated samples, but several samples have broad and/or skewed dose distributions. Only one sample is considered reliable and provides an age of 12.0 ± 0.6 ka. A radiocarbon age from organic sediments in the same unit yields an age of 14 025 ± 270 cal y BP. These two dates do not agree within 2 sigma, and this is likely related to reservoir and hard water effects of the radiocarbon sample. Sediments at the Raunis site fall into the Greenland Interstadial 1, but more detailed specification is not possible. The rest of the OSL ages are older than expected, likely due to incomplete bleaching during deposition. This means that stratigraphic reliability of this key site is likely hampered for further regional correlation.

Large-scale countrywide screening for tick-borne pathogens in field-collected ticks in Latvia during 2017\u20132019

BackgroundTick-borne diseases are of substantial concern worldwide in both humans and animals. Several hard tick species are of medical and veterinary interest in Europe, and changes in the range of tick species can affect the spread of zoonotic pathogens. The aim of the present study was to map the current prevalence and distribution pattern of ticks and related tick-borne pathogens in Latvia, a Baltic state in northern Europe.MethodsNearly 4600 Ixodes ricinus, I. persulcatus and Dermacentor reticulatus tick samples were collected in all regions of Latvia during 2017–2019 and were screened by molecular methods to reveal the prevalence and distribution pattern of a wide spectrum of tick-borne pathogens.ResultsNew localities of D. reticulatus occurrence were found in western and central Latvia, including the Riga region, indicating that the northern border of D. reticulatus in Europe has moved farther to the north. Among the analyzed ticks, 33.42% carried at least one tick-borne pathogen, and 5.55% of tick samples were positive for two or three pathogens. A higher overall prevalence of tick-borne pathogens was observed in I. ricinus (34.92%) and I. persulcatus (31.65%) than in D. reticulatus (24.2%). The molecular analysis revealed the presence of tick-borne encephalitis virus, Babesia spp., Borrelia spp., Anaplasma phagocytophilum and Rickettsia spp. Overall, 15 and 7 tick-borne pathogen species were detected in Ixodes spp. and D. reticulatus ticks, respectively. This is the first report of Borrelia miyamotoi in Latvian field-collected ticks.ConclusionsThis large-scale countrywide study provides a snapshot of the current distribution patterns of Ixodes and Dermacentor ticks in Latvia and gives us a reliable overview of tick-borne pathogens in Latvian field-collected ticks.

Power Centres and Marginal Landscapes: Tracking Pre- and Post-Conquest (Late Iron Age and Medieval) Land-Use in the Cēsis Castle Hinterland, Central Latvia

ABSTRACT During the late Iron Age, the eastern Baltic was inhabited by Finno-Ugric and Baltic speaking societies whose territories were conquered in the thirteenth century as a result of the crusades. This paper examines the degree to which indigenous landscapes were transformed as a result of the crusades, and the evidence for maintenance of indigenous land-use practices. Vegetation and land-use history are reconstructed using palynological data from Cēsis castle and its terriitory. Comparison is made with selected palynological, archaeological and documentary data across Livonia (Latvia and Estonia) and contrasted with the greater impact of the crusades in nearby Prussia. Despite the emergence of key power centres in the medieval period, including towns and castles such as Cēsis, many parts of the rural landscape remained largely unchanged by the crusades, particularly in those more marginal landscapes studied in this paper. Lower intensity land-use can be linked to poor agricultural soils but also reflect the limited colonisation of rural landscapes beyond the major towns and castles. Indigenous societies and practices survived to a greater degree, with later agricultural intensification in the fourteenth century reflecting the increasing political stability, growth of urban centres, establishment of serfdom and the development of the manorial system.

Ecology and calculation of population density of the protected saproxylic beetle species Boros schneideri (Panzer, 1796) (Coleoptera, Boridae) in capercaillie lek areas

Boros schneideri is an endangered saproxylic beetle species in Europe, included in the list of species for which micro-reserves are established in Latvia. Micro-reserves for capercaillie lek areas are created in similar habitats in Latvia; therefore, these sites might be suitable for B. schneideri and play an important role in the protection of the species. This study aimed to identify ecological factors affecting the occurrence of B. schneideri and to estimate the species’ population density in Central Latvia. In total, six micro-reserves (primarily established to protect capercaillie lek areas) and six, randomly picked, control territories were examined, including 304 forest stands and 312 pine snags. In total, 109 B. schneideri specimens were found. The most important ecological factors for B. schneideri were the age of the forest stand, the presence of deadwood in different stages of decomposition, and the number of snags per forest stand. All mentioned factors are important structural elements of natural forests; hence, B. schneideri can be considered as an indicator species of natural forest habitats. The most important ecological factors for B. schneideri on a micro-habitat scale are the area and thickness of the remaining bark, presence of Ascomycota fungi mycelium on a trunk, and trunk’s circumference. We suggest that B. schneideri is a pioneer species since larger areas of bark, as well as Ascomycota fungi mycelium are more often found on recently dead trees.

Ongoing shrinkage and fragmentation in the geographic range of the Natterjack Toad, Epidalea calamita, in Latvia and the East Baltic Region

Historical data indicate the presence of two Epidalea calamita population groups in Latvia in the past, one in western Latvia and another connecting populations from Estonia and Lithuania – in central Latvia. Both groups have experienced local extinctions that started after the Second World War in the coastal habitats around developing cities, where there were possible bottlenecks limiting population connectivity. Presently E. calamita’s range in Latvia has become split into four small- to medium-sized population groups with only two of them having connections with populations in neighbouring states, and this has produced major range gaps in Latvia dividing the once variably connected East Baltic E. calamita populations. The process of E. calamita range shrinkage continues, and we suggest that the main risk for population sustainability in the region is a combination of adverse local factors or occasional climate events with poor population connectivity and dispersal barriers.

Large herbivore population and vegetation dynamics 14,600–8300 years ago in central Latvia, northeastern Europe

This study seeks to explain how the large herbivore (large vertebrate, megafauna – terrestrial taxa with adults >45 kg) population density changed during abrupt postglacial climate and environmental change. The Lateglacial and Early Holocene (14,600–8300 years ago) were represented by various environmental and climate changes and a transition from a cold to a warm climate, with subsequent changes in flora and fauna. Using Lake Āraiši as a case study (Latvia, northeastern Europe), local to regional vegetation was reconstructed by analyzing plant macroremains and pollen from the lake sediment profile. Here, we present the first dung fungus spore-based qualitative reconstruction of large herbivore population density from northeastern Europe. Although there was no distinct pattern of large herbivore population variability during the Lateglacial and Early Holocene, higher densities were suggested during warm and relatively stable climatic and environmental conditions. Our findings imply that herbivores did not constantly live at high densities around one lake but rather were dynamic and moved/migrated according to their needs. Because large herbivores reintroduced today live in reserves (commonly fixed areas surrounded by physical borders), they might be more vulnerable to rapid climatic and environmental change compared to those mammals that lived during the Lateglacial and Early Holocene. Hence, they would have only two possible options – adapt or go extinct.

Genetic Parameters of Growth Traits and Stem Quality of Silver Birch in a Low-Density Clonal Plantation

Silver birch (Betula pendula Roth) is productive on abandoned agriculture land, and thus might be considered as an option for profitable plantation forestry. Application of the most productive genotypes is essential. However, information about genetic gains in low-density plantations is still lacking. A 40-year-old low-density (400 trees ha−1) plantation of 22 grafted silver birch plus-tree clones growing on former agricultural land in the central Latvia was studied. Although grafted plantations are not common in commercial forestry, the trial provided an opportunity to assess genetic parameters of middle-aged birch. The plantation that had reached the target diameter for final harvest (DBH (diameter at breast height) = 27.7 ± 5.5 cm) had an 85% survival rate, and stemwood productivity was 5.25 m3 ha−1year−1. Still, rootstock × scion interaction and cyclophysis might have caused some biases. Broad-sense heritability (H2) ranged from 0.02 for probability of spike knots to 0.40 for branch angle. Estimated H2 for monetary value of stemwood was 0.16. In general, the correlations between growth and stem quality traits were weak, implying independent genetic control, though branchiness strongly correlated with diameter at breast height. The monetary value of stemwood strongly correlated with productivity traits. The observed correlations suggested that productivity and stem quality of birch might be improved simultaneously by genetic selection.

Proportion of knotty wood in stems of 28-year old lodgepole and Scots pine in experimental plantation in Zvirgzde, Latvia

AbstractIn forestry, alien tree species are planted to maximize yield from a stand by increasing productivity and decreasing environmental risks. In Eastern Europe, lodgepole pine (Pinus contortavar.latifolia) might be used as a source of biomass and industrial wood; however, before any recommendations are given, possible gains of the novel species should be scrupulously evaluated. In this study, we compared volume and proportion of knotty stemwood (VKN) of native Scots pine (Pinus sylvestris) from first generation seed orchards and provenances of alien lodgepole pine [Fort Nelson (58°38’ N, 122°41’ W) and Summit Lake (54°24› N, 122°37› W)] at the age of 27 years growing in central Latvia. We also assessed the relationships between VKN and several morphometric parameters.Stem diameter of both species was similar; however, Summit Lake provenance of lodgepole pine exceeded Scots pine in height, while Fort Nelson provenance was lower than Scots pine. Although Scots pine produced nearly two times less whorls than lodgepole pine, volume of knotless stemwood did not differ significantly between the species; though it was higher for Summit Lake provenance of lodgepole pine compared to Scots pine. In contrast, the proportion of VKN differed significantly between both the species and the provenances. Scots pine showed the lowest proportion of VKN (~ 9%) and Fort Nelson provenances of lodgepole pine showed the highest proportion of VKN (~ 14%). Thus, Summit Lake appears more suitable for the production of industrial wood amongst the provenances of lodgepole pine; nevertheless, higher quantity of leftover material is expected. Some morphometric parameters correlated with VKN and the proportion of VKN, but these relationships differed between species and provenances. The total cross-section of branches was the best predictors of VKN for Scots pine and Fort Nelson provenance of lodgepole pine, while stem diameter showed the strongest correlation for Summit Lake provenance. Number of whorls and mean diameter of living branches were the best predictors of the proportion of VKN for lodgepole pine and Scots pine, respectively. Accordingly, morphometric parameters might be useful for the selection of the best trees of lodgepole pine.

New luminescence ages reveal Early to Middle Weichselian deposits in central Latvia

New optically stimulated luminescence (OSL) ages show that sandy deposits overlain by Late Weichselian subglacial till in central Latvia are of Early to Middle Weichselian age. The finer chronological resolution of unconsolidated sediment deposition in the Central Latvian Lowland (CLL) remains relatively unstudied, and here we provide a first characterisation of the deposits with respect to their age. Three OSL ages ranging between 84 ± 9 ka and 112 ± 11 ka suggest that the deposits studied in the CLL are of Early Weichselian age (MIS 5). We found no Middle Weichselian deposits in the CLL, and assume that any such younger sediments might have been eroded during the advance of the Zemgale Lobe in the Late Weichselian. One site, in the ice-marginal zone adjacent to the interlobate area, has nevertheless deposits dated to 44 ± 10 ka corresponding to the Middle Weichselian (MIS 3). Our results are compatible with existing ESR ages on three sets of Portlandia arctica shells from the central part of the lowland; the shells had been incorporated into glacial deposits during later glacial advances. Finally, our findings largely support ice-free conditions during the Early and Middle Weichselian in the middle and southern part of central Latvia.

Main drivers affecting the Holocene sedimentary record – implications from small lake in Latvia

A multi-indicator paleolimnological study of sediments from Lake Ķūži (central Latvia) was used to obtain a comprehensive record of environmental changes in the Holocene. Periodicity in the changes and the main drivers (lake basin development, catchment properties, climate, human activities) of the sedimentary record was studied. In order to comprehend the whole-lake sedimentation during the Holocene, a detailed multiindicator record from the central part of the lake was integrated with records of sediment mass accumulation rates from four cores from different parts of the lake and a GPR (ground-penetrating radar) survey of the lake basin. The observed changes in the sedimentation regime that took place during the early Holocene are strongly linked with variations in climatic conditions, but the catchment and lake basin also played an important role. In the middle Holocene the water level was stable and the lake was influenced by climate mediated through changes in the catchment vegetation. Around 5 000 cal. BP sedimentation pattern changed, and three of the four main drivers made a comparably strong impact on the sedimentary signal. Since 2 000 cal. BP multiple indicators point to a major disturbance clearly related to human activity, which conceals the impact of the natural drivers.

Landscape change in central Latvia since the Iron Age: multi-proxy analysis of the vegetation impact of conflict, colonization and economic expansion during the last 2,000 years

This study represents the first detailed multi-proxy palaeoenvironmental investigation associated with a Late Iron Age lake-dwelling site in the eastern Baltic. The main objective was to reconstruct the environmental and vegetation dynamics associated with the establishment of the lake-dwelling and land-use during the last 2,000 years. A lacustrine sediment core located adjacent to a Late Iron Age lake-dwelling, medieval castle and Post-medieval manor was sampled in Lake Āraisi. The core was dated using spheroidal fly-ash particles and radiocarbon dating, and analysed in terms of pollen, non-pollen palynomorphs, diatoms, loss-on-ignition, magnetic susceptibility and element geochemistry. Associations between pollen and other proxies were statistically tested. During ad 1–700, the vicinity of Lake Āraisi was covered by forests and human activities were only small-scale with the first appearance of cereal pollen (Triticum and Secale cereale) after ad 400. The most significant changes in vegetation and environment occurred with the establishment of the lake-dwelling around ad 780 when the immediate surroundings of the lake were cleared for agriculture, and within the lake there were increased nutrient levels. The highest accumulation rates of coprophilous fungi coincide with the occupation of the lake-dwelling from ad 780–1050, indicating that parts of the dwelling functioned as byres for livestock. The conquest of tribal lands during the crusades resulted in changes to the ownership, administration and organisation of the land, but our results indicate that the form and type of agriculture and land-use continued much as it had during the preceding Late Iron Age.