Search

The exploitation of peatlands in Estonia, which began in the 17th century, has degraded them to a great extent. Consequently, cutover and drained peatlands have become the sources of CO2. Global warming has led to a need for policies focusing on the protection and restoration of drained and degraded peatlands. Hence, to compare the effect/progress of restoration with the past pristine ecosystem baseline before the peatland was destroyed by cutting, we examined a peat core from North Estonia using chronology based on 14C by analyzing several proxies in high resolution including testate amoebae, plant macrofossils, pollen, non-pollen palynomorphs, and diatoms. The results revealed a striking ecological contrast between the pristine (ca. 2 kyrs) and restored state (currently) of the peatland. The pristine state was characterized by a domination of Sphagnum fuscum/rubellum and Archerella flavum, suggesting that extraction area of Hara peatland was a wet and stable ombrotrophic bog. As a result of peat exploitation, deposits comprising the last ca. 2 kyrs were cut. In turn an important feature of the restored section of the peat core was the domination of a green algae (Chlorophyta) and Eriophorum vaginatum as well as testate amoebae species Arcella discoides, which is considered an indicator of hydrological instability. The main difference between the predisturbed and restored parts of the peat core section was that a minor cover of peat-forming Sphagnum and mixotrophic testate amoebae was present in the top inundated part. We state that a healthy raised bog—the target of restoration—should consist abundant mixotrophic testate amoebae such as Archerella flavum and Hyalosphenia papilio which are good indicators of a well-functioning Sphagnum bog ecosystem even if the Sphagnum species differ from the reconstructed ecological baseline conditions. Our study highlights the extensive damage caused to the peat-forming ombrotrophic peatland by extraction and how difficult, challenging, and time-consuming is the process of ecological restoration.

Even though airfields, which are often anthropologically modified natural areas, are continuously influenced by human activities, their soils are still dynamic ecosystems containing various habitats for microscopic groups of organisms which are often ignored. In this exploratory study, the microarthropod fauna, Collembola (Hexapoda) and oribatid mites (Acari: Oribatida), and diatom (Bacillariophyta) flora were identified in three Estonian airfields, both runway sides and snow-melting sites were investigated. The communities of these airfields shared approximately 10-60% of the species belonging to each studied bioindicator group. The shared species were generally characteristic of a broad habitat spectrum. Communities were also characterized based on their species richness and diversity and in relation to location and the purpose of different airfield areas (e.g. snow-melting sites vs. runway sides). Also, species indicative of a specific airfield or purpose of the area within the airfield were identified using Indicator Species Analysis. Some possible linkages between airfield properties and communities, e.g. airfield that had highest pollutant concentrations had also maintained high diversity and species richness, were noted. Despite the contamination levels the airfield soils had still maintained a functioning soil ecosystem.

Peatlands are globally important ecosystems for their habitats, carbon sink and freshwater reservoir functions. Estonia is among the most peatland-rich countries worldwide with ca 20% (9,150 km2) of its land area covered with peat soils. Majority of these peatlands, however, are altered by the drainage for the agriculture, forestry and peat extraction that has led to a degradation of peatland ecosystems, and declined their functioning. The rapid loss of peatland habitats, subsidence of peat soils and carbon emissions after water level drawdown have highlighted the need for the ecological restoration of drained peatlands. Although the first restoration attempts in the early 2000s in Estonia covered only minor areas, the current increase of restoration projects in quantity and quality has been promising, and the aim to restore 10,000 ha of degraded sites in Estonia for 2020 is likely to be implemented.

Les tourbières sont des écosystèmes importants à l’échelle mondiale pour leurs habitats, leur puits de carbone et leurs fonctions de réservoirs d’eau douce. L’Estonie est l’un des pays les plus riches en tourbières au monde avec environ 20 % (9 150 km²) de son territoire couvert de sols tourbeux. Cependant, la majorité de ces tourbières sont altérées par le drainage pour l’agriculture, la sylviculture et l’extraction de la tourbe, cette dernière ayant entraîné une dégradation des écosystèmes tourbeux et diminué leur fonctionnement. La perte rapide d’habitats de tourbières, l’affaissement des sols tourbeux et les émissions de carbone suite à la baisse du niveau de l’eau ont mis en évidence la nécessité d’une restauration écologique des tourbières drainées. Bien que les premières tentatives de restauration en Estonie au début des années 2000 n’aient porté que sur des zones mineures, l’augmentation actuelle du nombre et de la qualité des projets de restauration sont prometteuses, et l’objectif de restaurer 10 000 ha de sites dégradés en Estonie d’ici 2020 devrait être atteint.

Calcareous spring fens are among the rarest and most endangered wetland types worldwide. The majority of these ecosystems can be found at high latitudes, where they are affected by above average rates of climate change. Particularly winter temperatures are increasing, which results in decreased snow cover. As snow provides an insulating layer that protects ecosystems from subzero temperatures, its decrease is likely to induce stress to plants. To investigate the sensitivity of the bryophyte community – key to the functioning of calcareous spring fens – to changing climatic conditions, we studied the annual variation in ecophysiology of two dominant bryophytes: Campylium stellatum and Scorpidium scorpioides. Further, a snow removal experiment was used to simulate the effect of changing winter conditions. In both species, we observed lowest efficiency of photosystem II (Fv/Fm) in spring, indicating physiological stress, and highest chlorophyll-a, -b and carotenoid concentrations in autumn. Snow removal exacerbated physiological stress in bryophytes. Consequently Fv/Fm, pigment concentrations and chlorophyll to carotenoids ratios declined, while chlorophyll-a to -b ratios increased. Moreover, these effects of winter climate change cascaded to the growing season. C. stellatum, a low hummock inhabitor, suffered more from snow removal (annual mean decline in Fv/Fm 7.7% and 30.0% in chlorophyll-a) than S. scorpioides, a hollow species (declines 5.4% and 14.5%, respectively). Taken together, our results indicate that spring fen bryophytes are negatively impacted by winter climate change, as a result of longer frost periods and increased numbers of freeze-thaw cycles in combination with higher light intensity and dehydration.

Relative sea level (RSL) changes and the palaeogeography of a Neolithic hunter-fisher-gatherer settlement site on the former shore of the Gulf of Finland in the city centre of Tallinn were reconstructed by implementing GIS in landscape modelling based on archaeological, sedimentary and shore displacement data. AMS radiocarbon dating of mammal bones from the cultural layer suggests the existence of the hunter-fisher-gatherer settlement around 5.1–4.8 cal. ka BP on a seaward inclining sandy beach of Tallinn palaeo-bay c. 100 m from the Litorina Sea shoreline and at about 2.4 m above the coeval sea level. The shoreline passed the study site at about 5.8 cal. ka BP and retreated towards northeast with an average speed of 13 m per century, while the RSL lowered by c. 2.5 mm annually. Combining radiocarbon dates of terrestrial and marine mammal bones from the Neolithic cultural layer, a marine reservoir effect of 35014C years for the brackish-water Baltic Sea was calculated. By using high-resolution archaeological data in combination with RSL and other geological proxies, we demonstrate new possibilities to reconstruct the palaeoenvironment of deeply buried coastal settlement sites and to predict a possible continuation of the cultural layer in heavily built-up areas.

Bogs comprise various niches that are ideal habitats for diatoms. Even though diatoms are widely used bioindicators in many aquatic ecosystems, little is known about their within-site distribution and versatility in bogs. The abundance of bogs in hemiboreal region offers a good opportunity to study the variability of diatom assemblages in different bog habitats and factors influencing it. This study aims to describe the diatom assemblages (1) in the most common bog ecotopes and (2) along the microtopography, and (3) to evaluate the extent to which abiotic environmental parameters (i.e. water table, electric conductivity, pH, moisture and shading) affect the diatom assemblages. According to our results, the most widespread and abundant species are typical bog-inhabiting acidophilic taxa, such as Eunotia paludosa, Kobayasiella parasubtillissima and E. bilunaris. Multivariate analyses showed that some patterns in different microhabitats and ecotopes can be distinguished according to diatom assemblages. In this study, the diatom assemblages were affected by moisture, shading and pH. The study demonstrates the potential usefulness of diatom assemblages as bioindicators to provide additional information about the microsite conditions in bogs.