Afforestation of abandoned peat extraction sites with Scots pine (Pinus sylvestris L.) as a solution of climate change mitigation

On a global scale, ambitious climate change mitigation targets are set. By 2050, the European Union is expected to be climate neutral which means that the greenhouse gas (GHG) emissions will not exceed removals. This initiative is also supported by Latvia. For businesses and carbon intensive industries transition to climate neutral economy will be provided by Just Transition Fund. The direction of the peat sector towards climate neutrality will promote research and innovation as well as restoration of peat extraction sites. These are also the objectives of implementing the Just Transition Fund for investments in Latvia. Studies on management of peat soils to improve the calculation of greenhouse gas (GHG) emissions have been carried out in Latvia within LIFE REstore project. The aim of the study is to assess the impact of afforestation of abandoned peat extraction sites with Scots pine (Pinus sylvestris L.) on GHG emissions compared to retaining of the existing situation (abandoned peatlands with poorly developed vegetation). Afforestation of degraded peatlands can contribute to significant GHG reduction in wetlands – up to 20% of the net GHG emissions due to wetlands management. The most of the GHG mitigation potential is ensured by accumulation of CO2 in living biomass.

Greenhouse Gas Balance of Sphagnum Farming on Highly Decomposed Peat at Former Peat Extraction Sites

For two years, we quantified the exchange of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) at two different large-scale Sphagnum farming sites. At both, peat extraction left a shallow layer of highly decomposed peat and low hydraulic conductivities. One site was characterized by preceding multi-annual inundation and irrigated by ditches, while the other one was inoculated directly after peat extraction and irrigated by ditches and drip irrigation. Further, GHG emissions from an irrigation polder and the effect of harvesting Sphagnum donor material at a near-natural reference site were determined. GHG mitigation potentials lag behind the results of less decomposed sites, although our results were also affected by the extraordinary hot and dry summer 2018. CO2 exchanges ranged between -0.6 and 2.2 t CO2-C ha−1 y−1 and were mainly influenced by low water table depths. CH4 emissions were low with the exception of plots with higher Eriophorum covers, while fluctuating water tables and poorly developing plant covers led to considerable N2O emissions at the ditch irrigation site. The removal of the upper vegetation at the near-natural site resulted in increased CH4 emissions and, on average, lowered CO2 emissions. Overall, best plant growth and lowest GHG emissions were measured at the previously inundated site. At the other site, drip irrigation provided more favourable conditions than ditch irrigation. The size of the area needed for water management (ditches, polders) strongly affected the areal GHG balances. We conclude that Sphagnum farming on highly decomposed peat is possible but requires elaborate water management.

ALTERNATIVE DIRECTIONS OF PEAT USE

Peat extraction and processing in the world is a highly profitable and promising type of business. This section describes and discloses the essence of alternative uses of peat. The physical and chemical properties of peat are given. Emphasis is placed directly on the use of peat in the world and in Ukraine.

EFFICIENCY OF FOREST RECULTIVATION OF LAND DISTURBED BY PEAT EXTRACTION (ON THE EXAMPLE OF THE BASYANOVSKY DEPOSIT)

Приведены результаты оценки эффективности лесной рекультивации земель, нарушенных при добы- че торфа на Басьяновском торфяном месторождении. Целью исследований явилось выявление наиболее эффективных вариантов лесной рекультивации на основе оценки состояния лесных культур, созданных на отработанных торфяниках после их технической рекультивации и мелиоративной подготовки. В основу исследований положен метод пробных площадей. В результате исследований установлено, что эффектив- ность рекультивации определяется водным режимом осушенных территорий, который зависит от расстоя- ния между осушительными каналами, их состояния. На большинстве обследованных участков состояние лесных культур оценивается как хорошее. Основные причины гибели лесных культур – это угнетение их мягколиственными породами, поврежде- ние культур сосны дикими животными (лосями) и вымокание. Причиной угнетения культур мягколиствен- ными породами явилось отсутствие своевременного проведения мероприятий по уходу за молодняками (прочисток). При этом угнетению более подвержены культуры сосны. Лесные культуры ели оказались в целом более эффективными по сравнению с культурами сосны. При посадке культуры ели целесообразно высаживать под полог мягколиственных пород. На рекультивированных участках с нормальным водным режимом наблюдается формирование живого напочвенного покрова, типичного по составу для мелкотравно-зеленомошных и разнотравно-зеленомош- ных типов леса. Полученные результаты имеют практическое значение и могут быть использованы недропользователя- ми, органами исполнительной власти в области лесных отношений, проектно-изыскательскими организа- циями при проектировании, организации и проведении работ по лесной рекультивации на отработанных торфяных месторождениях. The article contains the results of assessing the effectiveness of forest reclamation of lands disturbed during peat extraction at the Basyanovskiy peat deposit. The aim of the research was to identify the most effi cient options for forest reclamation based on an assessment of the state of forest crops created on spent peatlands after their technical reclamation and reclamation preparation. The research is based on the trial plot method. As a result of the research, it was found that the effi ciency of reclamation is determined by the water regime of the drained territories, which depends on the distance between the drainage canals, their condition. In most of the surveyed areas, the state of forest cultures is assessed as well. The main reasons for the death of forest crops are their oppression by soft-leaved species, damage to pine crops by wild animals (elks) and soaking. The reason for the oppression of crops by soft-leaved breeds was the lack of timely measures for the care of young stands (cleanings). At the same time, pine crops are more subject to oppression. Spruce forest crops were generally more effective than pine crops. When planting spruce crops, it is advisable to plant under the canopy of soft-leaved species. In the reclaimed areas with a normal water regime, the formation of a living ground cover is observed, typical in composition for small-grass-green moss and forb-green moss types of forest.The results obtained are of practical importance and can be used by subsoil users, executive authorities in the fi eld of forest relations, design and survey organizations in the design, organization and implementation of forest reclamation work at spent peat deposits.

Quantifying fluvial carbon losses from lowland peatland ecosystems across a drainage-impact spectrum

<p>The export of Dissolved Organic Carbon (DOC) and evasion of carbon dioxide (CO<sub>2</sub>) from inland waters is increasingly being recognized as a key part of the terrestrial carbon (C) cycle, with recent global estimates suggesting that the magnitude of the aquatic CO<sub>2</sub> conduit is equivalent to global Net Ecosystem Productivity (2.0 Gt C yr-1; Tranvik et al., 2009). However, a major weakness in the carbon balance estimation of terrestrial ecosystems, such as peatlands, is the poor quantification of DOC and CO<sub>2</sub> evasion fluxes associated with drainage waters. This has implications for conservation, land-use management and climate change mitigation. Whilst intact peatland systems typically sequester carbon, drainage reverts peatlands to being C sources due, primarily, to the degradation of organic peat soil. This study examines the export of C in fluvial pathways from relatively intact catchments to those that are heavily drained, and also from peatland sites undergoing restoration works. This research is being carried out parallel other linked studies that are quantifying the carbon gaseous emissions from directly from the different bogs in order to determine the comparative net carbon budgets.</p><p>This study will focus on three raised bog sites in the midlands of Ireland: one in near natural condition (Clara bog), one significantly drained and degraded due to peat extraction (Garryduff) and one undergoing rehabilitation following many years of peat extraction (Cavemount). Flumes and sondes, with fluorescent dissolved organic matter (fDOM), temperature/conductivity and turbidity sensors, have been installed on the sites. The fDOM measurements will be correlated to grab samples taken every two weeks to give half hour proxy measurements for DOC.</p><p>Preliminary results suggest that DOC flux from the heavily drained and mined peatland site is some 295 times higher than that from the catchment with minimal interference. In addition to this, drainage waters are super-saturated in CO<sub>2</sub> and rapidly evades back to the atmosphere resulting in an additional C loss. Thus, C losses in the drainage systems of peatland catchment areas are significantly under-reported and a significant source of C in countries with significant peat land cover such as Ireland. This research is thereby addressing the magnitude of C losses in fluvial pathways, the associated effects on ecosystem biodiversity and the effectiveness of restoration activities on mitigating against net C loss in degraded systems.</p>

Economic Assessment of Low Humidity Peat Production Practice

The article presents a milled peat production practice based on deep bed drying up to a harvesting moisture content of 35%. The task of the developed technology is to minimize and stabilize the harvesting humidity in the field drying of peat, thereby reducing the time and thermal impact on the peat organic matter during a forced finish drying. The applied method of peat extraction provides for variable milling depth and differentiation of cycle harvesting to increase the number of cycles and the harvester seasonal output. An economic feasibility study has been carried out by the method of determining the operating costs per ton of a marketable product for each technological operation. It consists in a comparative assessment of two technological processes: the production practice based on intensification of milled peat drying up to a harvesting moisture content of 35% and the conventional harvesting of milled peat with moisture content of 45%. The developed technology of milled peat extraction makes it possible to ensure the required quality parameters in terms of humidity (≤ 35%) and to preserve natural bituminous components. Based on the economic assessment results, it has been found that there is a slight increase in operating costs per ton of a marketable product in comparison with the conventional practice.

Sedimentation Patterns of Multiple Finnish Lakes Reveal the Main Environmental Stressors and the Role of Peat Extraction in Lake Sedimentation

Human land-use activities, especially in the peatlands, are under consideration as the mitigation and lowering of CO2 emissions from land-use practices is needed to address climate change. In Finland, approximately one third of the land surface is covered by peatlands, and around 50% of peatlands are ditched for forestry. Another 3% of peatlands are used for agriculture and approximately 1% for peat extraction. The effects of these different land-use practices, including changes in sediment depositional rates and sediment quality, need to be identified. This study analyzed 51 lakes that were subdivided into two groups: (1) a group of impacted lakes in which peat was recently extracted from the catchments and (2) a reference group consisting of lakes where peat had not been extracted from the basin, but in which other land-use activities had occurred. The overall aim of the study was to investigate if peat extraction caused excessive delivery and deposition of dry and organic matter in lakes that are located in their immediate downstream catchment areas. Differences in sediment accumulation were defined by comparing the overall sediment thickness and recent (post 1986) sedimentation levels to identify if there were differences in the sediment chemical composition or rate of organic matter deposition between groups and to identify possible land-use stressors that could explain the possible differences in sediment chemical assemblages or sedimentation rates. The results show moderate (cm scale) sedimentation rates in both impacted and reference lakes after 1986, while sediment chemical assemblages indicated the erosion and input of mineral soils to all of the studied lakes, rather than the input of organic materials. No statistically significant correlations were observed between selected environmental variables and the recent accumulation rates of carbon and dry matter. Moreover, significant changes in the stressors potentially affecting the chemical assemblages of pre- and post-disturbance sediments were not observed.