![]() However, several proxies, including tree-ring data, can be useful in acquiring reconstructions of past hydrological variability for a better understanding of current trends and predicting possible future scenarios. Continuous long-term instrumental series of GWL data from peatlands are very scarce, and there are few records as long-term as the records from Männikjärve bog in Estonia, which span from 1956 to the present. ![]() GWL is an important variable for modeling processes related to peatland ecology, hydrology, biogeochemistry, and greenhouse gas fluxes. Īssessing climatic effects on peatland hydrology is essential for evidence-based planning and management of peatlands for forestry (e.g., planning of ditch network maintenance) as well as peatland restoration, also considering climate mitigation and other ecosystem services. In peatlands, these signals can be linked to long-term GWL fluctuations and corresponding changes in site conditions related to climatic reasons or induced by human activities e.g., site modification by ditching affects the long-term variability of tree radial increment, introducing a positive trend for several post-drainage years. Low-frequency signals contained in ring-width series can be associated with tree size or age and various endogenous and exogenous disturbances. High-frequency signals extracted from tree-ring series can be utilized to address relationships with short-term climatic variability, and a number of studies have identified links between temperature and precipitation on tree radial growth at an annual scale using ring-width data of various tree species in Estonia and other countries in the Baltic region. Tree-ring data are useful for exploring the effects of soil moisture status and several other factors on tree and forest growth. By way of example, around 20% of the forest stands in Estonia are growing on organic soils. The area of peatlands drained for forestry varies by country, and in some regions, a considerable amount of commercial forests is located in such sites. Globally, the share of artificially drained peatlands is about 6%, but for Fennoscandia and the Baltics this figure is higher and the number of peatlands disturbed by ditching as a silvicultural treatment is substantial. Such activities often involved management of the hydrological regime, resulting in degraded or converted ecosystems with altered biodiversity and carbon uptake, although disturbed areas with less evident effects of human impact also exist e.g., in the case of failed or insufficient site modification. Throughout human history, peat and peatlands have been utilized for a wide range of purposes including fuel for heating, agriculture, timber production, and plantation soils improvement. Even in their natural state, peatlands are considered complex and dynamic ecosystems, but peatland management or land-use changes may induce even more rapid shifts affecting local hydrology. Hydrological variability of peatlands depends on various climatic factors and affects peatland vegetation and carbon storage dynamics. Peatland ecosystems are characterized by high soil moisture and partially decomposed vegetation accumulated as peat in soil layers. Understanding the links between climate and processes that involve peatland hydrology and vegetation responses is important since peatland ecosystems are key players in the global carbon cycle. Trends detected in single tree-ring chronologies may be linked to local peatland management or land-use changes, whereas common variations detected at multiple sites are more likely linked to hydrological changes in the peatlands associated with regional climate dynamics. In general, the best agreements were observed between the tree populations from Estonia and Belarus, but synchronous growth changes could also be detected between the Swedish and Estonian material. ![]() Several synchronous growth release events were detected, especially during the 1910s, 1930s, and around 19, indicating that hydrological shifts and associated tree growth responses have been governed by similar forcing mechanisms, at least during the 20th century. Fourteen tree-ring chronologies developed from 788 peatland Scots pines sampled at sites in Estonia, Belarus and Sweden were compared for common growth trends and possible links to regional climate dynamics. ![]()
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