Implementation of climate change mitigation measures in forestry has a key role to successfully f... more Implementation of climate change mitigation measures in forestry has a key role to successfully fulfil the climate change policy goals of Land use, land use change and forest sector set by the Paris Agreement to fully offset total GHG emissions in the country by CO2 removals in 2050. GHG emissions from organic soils in forest land have significant impact on total emissions of Latvia, however, high emissions also indicate the potential of climate change mitigation measures. This study aims to evaluate CO2 emissions from drained and naturally wet nutrient-rich forest soils to improve knowledge of forest management practice impact on GHG emissions. The study is conducted in 21 drained (Myrtillosa turf.mel. and Oxalidosa turf. mel.) and 10 naturally wet (Dryopterioso-caricosa and Filipendulosa) forest sites with nutrient-rich organic soils for 12 consecutive months. Soil total CO2 emissions were measured by closed manual non-transparent chamber method. The groundwater level, soil and air temperature were measured to evaluate factors affecting CO2 emission. Empirical data collected within the scope of the study showed high correlation (r = 0.85) between CO2 emissions and temperature, however, the groundwater level depth had no considerable impact on emissions. Total soil CO2 emissions from drained nutrient-rich organic soils ranged from 5.44 t ± 0.1 tC•ha-1 •yr-1 in black alder stands to 9.76 ± 2.47 tC•ha-1 •yr-1 in clearcut areas (average 7.35 ± 0.89 tC•ha•yr-1), while CO2 emissions from forest sites with naturally wet soil ranged from 5.73 ± 2.23 tC•ha-1 •yr-1 in spruce stands to 10.41 ± 4.33 tC•ha-1 •yr-1 in clearcut areas (average 7.02 ± 0.96 tC•ha-1 •yr-1). The study results demonstrate that drainage does not have significant effect on CO2 emissions.
The aim of the study is to evaluate carbon stock in litter and organic forest soils in Latvia as ... more The aim of the study is to evaluate carbon stock in litter and organic forest soils in Latvia as well as to characterize accumulation of carbon in litter in afforested lands. The study is providing empirically valid information about soil and litter carbon changes for the National greenhouse gas (GHG) inventory by using data from National forest inventory (NFI), forest soil monitoring demonstration project BioSoil and other studies. The study proves significance of organic forest soil carbon pool in Latvia and demonstrates necessity to extend NFI incorporated forest soil monitoring program to improve data on soil density in wet organic soils, as well as to integrate data characterizing water regime in forests. The acquired data also proves that the conservative approach of calculation of carbon stock changes in litter in afforested lands applied in the Latvia's National GHG inventory avoids overestimation of CO 2 removals. The data on litter carbon stock collected in this study is sufficient to estimate total carbon stock for stands dominated by most common tree species and long term impact of changes of species composition. Measurements of organic soil and litter thickness should be continued by NFI and integrated with more detailed soil monitoring to increase accuracy of carbon stock estimates and gather data necessary for verification of modelling data, particularly in afforested lands and due to change of dominant species.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
<p>In the terrestrial biosphere, peatlands represent the most important long-term s... more <p>In the terrestrial biosphere, peatlands represent the most important long-term soil carbon storage. They cover only 3% of the land surface but are responsible for about one-third of the total. Ecosystem degradation and changes made in hydrology may affect the biogeochemistry of peatlands and, together with projected global warming, may lead to significant changes in greenhouse gas fluxes. Aeration of peatlands increases organic matter's aerobic decomposition and enhances wetlands’ change from a net carbon sink to a carbon dioxide source and low soil water content in drained histosols results in lower CH<sub>4</sub> emissions. In contrast, N<sub>2</sub>O emissions may increase due to increased mineralization and more favorable conditions for nitrification.</p><p>However, soil CH<sub>4</sub> and N<sub>2</sub>O fluxes in peatlands are spatially and temporally (interannual, seasonal) variable, and there is little detailed information on drained nutrient-rich organic soils in the hemiboreal zone. We conducted a two-year study in drained peatland forests with different tree species Scots pine<em> </em>(<em>Pinus sylvestris</em>), Norway spruce (<em>Picea abies</em><em>), </em>birch<em> </em>(<em>Betula sp</em><em>.</em>), and black alder (<em>Alnus glutinosa</em>) and with various water levels and a natural wetland (fen) as a reference site in Estonia and Latvia from January 2021 to December 2022.</p><p>CH<sub>4</sub> and N<sub>2</sub>O fluxes were measured twice per month using the manual static chamber method. Environmental parameters in soil, such as groundwater level, temperature, and moisture were monitored and stored hourly by a data logger. Detailed studies of soil physio-chemical parameters and microbial community were conducted to relate greenhouse gas fluxes with environmental conditions.</p><p>Our preliminary results for the first year showed that all drained forest soils with low groundwater levels were annual methane sinks (−48.9 ± 12.9 μg m<sup>−‍2</sup> h<sup>−‍1</sup>), whereas the reference fen studied had a higher emission potential of 396 ± 214 μg m<sup>−‍2</sup> h<sup>−‍1</sup>. In contrast, birch and alder forests with poorly drained soils consumed less CH<sub>4</sub> and were annual emitters than artificially drained sites. Methane flux had a statistically significant correlation with water level and soil temperature. Most of the sites were annual emitters of N<sub>2</sub>O; wetter forest sites were higher emitters (21.0 ± 10.49 μg m<sup>−‍2</sup> h<sup>−‍1</sup>) than drier sites (17.97 ± 4.8 μg m<sup>−‍2</sup> h<sup>−‍1</sup>). Higher N<sub>2</sub>O emissions and temporal variability were associated with sites where water levels exhibited large seasonal fluctuations. N<sub>2</sub>O flux was controlled by soil temperature and moisture content, and emission peaks occurred in spring (freeze-thaw period).</p><p>This research was supported by the LIFE programme project "Demonstration of climate change mitigation potential of nutrients rich organic soils in the Baltic States and Finland", (2019-2023, LIFE OrgBalt, LIFE18 274CCM/LV/001158).</p>
To evaluate the potential of establishing a deciduous tree plantation on an industrial cutaway pe... more To evaluate the potential of establishing a deciduous tree plantation on an industrial cutaway peatland over an 8 ha large experimental site was established in the central part of Latvia and silver birch (Betula pendula Roth) and black alder (Alnus glutionsa (L.) Gaertn.) tree species were planted. As it is a harsh and unfavorable environment wood ash, otherwise a waste product, was used as a fertiliser and liming material in three applications (5, 10 and 15 t ha-1). In comparison with control, fertilised soils had higher Ca, Mg, P amounts, whilst the most substantial difference was seen in the amount of K. Application of wood ash also considerably increased soil pH from 3.5 (Control) to 5.9 (15 t ha-1). Even though showing reduced growth in unfertilised soil both alder and birch seedling survival rate was higher than 80%. The highest survival rate for birch was under wood ash treatment, while alder under 10 t ha-1 wood ash fertiliser treatment showed the lowest survival rate i.e. 81%. In total, more than 60 naturally occurring vegetation species were observed in the first and the second year of sites establishment after fertilisation. Species as Betula pendula, Betula pubescens, Populus tremula, Pinus sylvestris, Salix spp. often occurred from natural vegetation regeneration. Already after one year of vegetation succession increase in tree and shrub species cover was observed, suggesting perhaps such areas can be naturally afforested thus creating a more heterogeneous forest stand. In such a way sustaining economic use of land resources after peat extraction while providing other ecosystem services.
The study represents results on remote sensing methods based evaluation of land use and land use ... more The study represents results on remote sensing methods based evaluation of land use and land use changes in former and existing peat extraction areas in Latvia. The aim of the study is to elaborate activity data set for the National GHG inventory for the wetlands remaining wetlands for peat extraction. The study results provide sufficient data for application of the default emission factors for the peat extraction sites and flooded lands. Abandoned peat extraction fields, which are not yet afforested, flooded or rewetted should be reported as peat extraction sites following a conservative approach in application of the emission factors. The study results can be used to report land use changes since 1990; however, linearized approach in calculation of the land use change may result in overestimation or underestimation of GHG emissions in certain periods of time. According to study results, the area of peat extraction sites is considerably bigger than currently reported in the National GHG inventory, mainly due to considerable areas of abandoned peat extraction fields. Flooded lands may be a significant source of emissions and should be introduced in the National GHG inventory to secure consistency of reporting. Methodology for calculation of GHG emissions from flooded lands should be also elaborated. It is also necessary to elaborate emission factors for fertile and nonfertile peat extraction sites and continue work on separation of different soils in the inventory to increase accuracy of calculations.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
According to general knowledge rewetting of drained organic soils is a measure that can reduce ne... more 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.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Peer reviewed publications were used as the data source. Original data collection in the publicat... more Peer reviewed publications were used as the data source. Original data collection in the publications was by (i) inventories integrating change in soil C-stock, and (ii) CO2 monitoring fluxes by (a) chamber technique and/or (b) by eddy covariance technique. All CH4 and N2O fluxes monitored between soil and the atmosphere were by the chamber technique. Basic criteria for CO2, CO2-C, CH4 and N2O data inclusion to the database was: for soil inventory studies, estimate on soil C stock change averaging change over specified period of years was attainable, for eddy covariance studies, at least one annual soil CO2 balance estimate was attainable, for chamber studies, at least one annual soil CO2 balance estimate was attainable, for chamber studies, at least one annual or warm season soil total or soil heterotrophic cumulative CO2 emission estimate with potential to form respective annual soil CO2 balance estimate by using existing supplementary site-specific or site-type specific data was attainable, at least one annual soil CH4 balance or warm season cumulative soil CH4 flux estimate was attainable, at least one annual soil N2O balance or warm season cumulative soil N2O flux estimate was attainable. Annual soil CO2 balance estimates based on soil inventories were added into the database 'as is' basis. CO2 flux monitoring data based on chamber techniques usually necessitated further processing (e.g., measures on litter production and decomposition rates, evaluation of flux contributions from root respiration and/or ground vegetation dark respiration) before the estimate quantified soil CO2 balance. Such site specific or site-type specific supplementary data were collated from the relevant literature, authors and other specialists, and incorporated to CO2 flux data (applied changes are listed in Table S1-1 and in Data repository). Forming annual soil CH4 and N2O balance estimates in the data was less complicated because annualization was the only supplementary measure implemented to the estimates reported as cumulative warm season flux. Annualization. For studies providing GHG flux estimate based on warm season measurements, we used coefficient to supplement relative cold season fluxes. As in IPCC (2014), this was be made by adding flux-proportion of colder period GHG flux estimate which was based on the cold season (winter) measurements and flux estimates in boreal and subarctic peatlands. The values based on cold season flux proportion provided in Dise (1992), Alm et al. (1999), Aurela et al. (2002), Kim et al. (2007) and Leppälä et al. (2011). As the annualization coefficients we topped seasonal GHG flux estimate by 15.9% for CO2, by 16.7% for CH4, and 21.4% for N2O. Applied changes are listed in Table S1-1 and Table S1-2. Root respiration subtraction from the total respiration. Likely the largest and most coherent database providing both site type specific soil total (Rtot) and proportioned heterotrophic (Rhet) CO2 emissions in drained organic soils is analysed in Ojanen et al. (2010), and the database was available for our analyses. We split flux data from Ojanen et al. (2010) into ombrotrophic (n= 12) and minerotrophic (n= 53) site types and tested linear regression between CO2tot that includes autotrophic respiration of tree root systems and CO2het from soil. The analysis resulted in following linear regressions (95% confidence limits) for heterotrophic CO2het emission: emission = 1.1 + 0.39 × Rtot (R 2 = 0.641, SEmodel = 139, SEcoefficient = 183) for ombrotrophic sites and emission =-1.55 + 0.52 × Rtot (R 2 = 0.723, SEmodel = 217, SEcoefficient = 124) for minerotrophic sites. These equations were applied to form CO2het from the provided CO2tot estimates in data where CO2het was not readily available, and these estimates are listed in Table S1-1. Litter production and decomposition rates. Applied changes and data sources are shown in Table S1-1. Relative data reliability weighting. We determined a weigh for each annual soil GHG balance estimate formed from closed chamber data on the basis of estimate relative reliability (i.e. 1= no major issues
Flooded Land is defined as water bodies where human activities have caused changes in the amount ... more Flooded Land is defined as water bodies where human activities have caused changes in the amount of surface area covered by water, typically through water level regulation. Former peat extraction fields are a type of flooded lands which are often mentioned as significant source of greenhouse gas (GHG) emissions. In Latvia, the area of flooded lands in former peat extraction fields is 5.3 kha. The aim of the study is to evaluate GHG emissions from flooded former peat extraction fields to define that the flooded lands are the key source of GHG emissions and approve that further studies are necessary to elaborate country specific emission factors. The study is implemented in three areas in central part of the country, where peat extraction was stopped 25-35 years ago. Measures continued for 12 months, in 9 subplots, each was represented by 3 measurement points. Water and air temperature, as well as water level was measured during the study. According to the study results, flooded areas are a significant source of CO 2 emissions (967±107 kg CO 2-C ha-1 yr-1); however, the most significant agent of GHG emissions in flooded areas is methane (CH 4)-435±98 kg CH 4-C kg ha-1 yr-1. Flooded areas are not significant source of nitrous oxide (N 2 O) emissions. The net emissions from flooded areas are 18.1±3.7 tons CO 2 eq ha-1 yr-1. According to the study results, flooded lands are a significant (one of the largest) source of emissions, and further studies are necessary to improve GHG modelling solutions and activity data.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
The aim of the study is to evaluate greenhouse gas (GHG) fluxes from stems in black alder (Alnus ... more The aim of the study is to evaluate greenhouse gas (GHG) fluxes from stems in black alder (Alnus glutinosa (L.) Gaertn.) and birch (Betula pendula Roth) stands with drained and naturally wet nutrient rich peat soils, as well as to evaluate correlation between the GHG fluxes, soil temperature and groundwater level. The study was implemented in 8 forest standsthree black alder stands with nutrient rich peat soil (stand types according to national classification-Dryopterioso-caricosa and Filipendulosa) and 5 birch stands with peat soil (stand type Oxalidosa turf. mel. and Dryopterioso-caricosa). Measurement of GHG fluxes was continued for 12 months using Gasmet DX4040 FTIR analyser and removable non-transparent chambers of fixed volume and area. GHG fluxes were measured at 0.5, 1.0 and 1.5 m height on 3 trees in every stand. According to the study results the average CH4 emissions from stem surface in birch stands are 6.9 ± 6.2 g CO2 eq m-2 •yr-1 and in black alder stands 1.0 ± 3.2 g CO2 eq m-2 •yr-1. Groundwater level significantly effects CH4 emissionsif it remains above 15 cm during summer, the CH4 emissions from stem increases to 84.0 ± 25.2 g CO2 eq. m-2 •yr-1. Tree stems in drained peat soils are not a source of CH4 emissions. According to the study results tree stems in peat soils are not producing N2O emissions.
20th International Scientific Conference Engineering for Rural Development Proceedings, May 27, 2021
The study compares 9 forest management scenarios in birch plantations in cropland and grassland w... more The study compares 9 forest management scenarios in birch plantations in cropland and grassland with mineral and organic soils. Calculation period is 40 years for all scenarios. The study proves that establishment of birch plantations leads to reduction of greenhouse gas (GHG) emissions by 317-1776 tons of CO2 eq. ha-1 or 7.9-44.4 tons of CO2 eq. ha-1 per year. The reduction of GHG emissions in birch plantations is significantly influenced by growth conditionsin organic soils GHG emission reduction is 6 times higher than in mineral soils. In plantations with mineral soils most of the GHG emission reductions occur during 40 years after the establishment. In organic soils GHG emission reduction continues steadily due to reduction in GHG emissions from soils compared to alternative management scenarios (grassland or cropland). Harvested wood products and the substitution effect of biofuels play an important role in reducing GHG emissions, in particular through the assumption that wood products are recycled into biofuels at the end of their useful life. Recommended type of soil preparation in the most cases is mounding, but taking into account soil scarification costs, the number of target trees in the plantation must be reduced (down to 1500 per ha-1). Early tending, felling of young stands and regenerative felling must also be adapted to growing conditions by managing more intensively areas with fertile soils and less intensivelyplantations with poor soils. In more fertile soils higher planting density may increase CO2 removals in the middle term. When planting 1500-2000 seedlings ha-1 , moderately fertile soils ensures higher CO2 removals. According to the study results establishment of birch plantations in farmland is one of the most effective solutions for reducing GHG emissions in the land use, land use change and forestry (LULUCF), as well as in agriculture sector, especially, if organic soils are afforested.
Forest mineral soil is one of the terrestrial carbon pools, and changes in forest management prac... more Forest mineral soil is one of the terrestrial carbon pools, and changes in forest management practices can affect the carbon stock in forest soil. The purpose of the study is to estimate temporal fertilization impact on mineral soil organic carbon stock, depending on fertilizers applied, forest stand type, different dominant tree species of the stands. Coniferous and birch forest stands with mineral soil in the central and eastern part of Latvia were selected for the experiment. The fertilizers used were wood ash and nitrogen containing mineral fertilizer. No significant differences in organic carbon stock in O horizon were detected 2-5 years after fertilization. A tendency of smaller organic carbon stock in upper mineral soil layers (0-10 cm, 10-20 cm) was found in most part of objects. Significantly smaller organic carbon stock was found in upper mineral soil layers (0-10 cm and 10-20 cm) in birch stands with wet mineral soil treated with ammonium nitrate if compared to the control plots, possibly due to a different soil moisture regime of forest stands. The positive and significant correlations between soil organic carbon and nitrogen stocks were found in most part of the objects.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Implementation of climate change mitigation measures in forestry has a key role to successfully f... more Implementation of climate change mitigation measures in forestry has a key role to successfully fulfil the climate change policy goals of Land use, land use change and forest sector set by the Paris Agreement to fully offset total GHG emissions in the country by CO2 removals in 2050. GHG emissions from organic soils in forest land have significant impact on total emissions of Latvia, however, high emissions also indicate the potential of climate change mitigation measures. This study aims to evaluate CO2 emissions from drained and naturally wet nutrient-rich forest soils to improve knowledge of forest management practice impact on GHG emissions. The study is conducted in 21 drained (Myrtillosa turf.mel. and Oxalidosa turf. mel.) and 10 naturally wet (Dryopterioso-caricosa and Filipendulosa) forest sites with nutrient-rich organic soils for 12 consecutive months. Soil total CO2 emissions were measured by closed manual non-transparent chamber method. The groundwater level, soil and air temperature were measured to evaluate factors affecting CO2 emission. Empirical data collected within the scope of the study showed high correlation (r = 0.85) between CO2 emissions and temperature, however, the groundwater level depth had no considerable impact on emissions. Total soil CO2 emissions from drained nutrient-rich organic soils ranged from 5.44 t ± 0.1 tC•ha-1 •yr-1 in black alder stands to 9.76 ± 2.47 tC•ha-1 •yr-1 in clearcut areas (average 7.35 ± 0.89 tC•ha•yr-1), while CO2 emissions from forest sites with naturally wet soil ranged from 5.73 ± 2.23 tC•ha-1 •yr-1 in spruce stands to 10.41 ± 4.33 tC•ha-1 •yr-1 in clearcut areas (average 7.02 ± 0.96 tC•ha-1 •yr-1). The study results demonstrate that drainage does not have significant effect on CO2 emissions.
The aim of the study is to evaluate carbon stock in litter and organic forest soils in Latvia as ... more The aim of the study is to evaluate carbon stock in litter and organic forest soils in Latvia as well as to characterize accumulation of carbon in litter in afforested lands. The study is providing empirically valid information about soil and litter carbon changes for the National greenhouse gas (GHG) inventory by using data from National forest inventory (NFI), forest soil monitoring demonstration project BioSoil and other studies. The study proves significance of organic forest soil carbon pool in Latvia and demonstrates necessity to extend NFI incorporated forest soil monitoring program to improve data on soil density in wet organic soils, as well as to integrate data characterizing water regime in forests. The acquired data also proves that the conservative approach of calculation of carbon stock changes in litter in afforested lands applied in the Latvia's National GHG inventory avoids overestimation of CO 2 removals. The data on litter carbon stock collected in this study is sufficient to estimate total carbon stock for stands dominated by most common tree species and long term impact of changes of species composition. Measurements of organic soil and litter thickness should be continued by NFI and integrated with more detailed soil monitoring to increase accuracy of carbon stock estimates and gather data necessary for verification of modelling data, particularly in afforested lands and due to change of dominant species.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
<p>In the terrestrial biosphere, peatlands represent the most important long-term s... more <p>In the terrestrial biosphere, peatlands represent the most important long-term soil carbon storage. They cover only 3% of the land surface but are responsible for about one-third of the total. Ecosystem degradation and changes made in hydrology may affect the biogeochemistry of peatlands and, together with projected global warming, may lead to significant changes in greenhouse gas fluxes. Aeration of peatlands increases organic matter's aerobic decomposition and enhances wetlands’ change from a net carbon sink to a carbon dioxide source and low soil water content in drained histosols results in lower CH<sub>4</sub> emissions. In contrast, N<sub>2</sub>O emissions may increase due to increased mineralization and more favorable conditions for nitrification.</p><p>However, soil CH<sub>4</sub> and N<sub>2</sub>O fluxes in peatlands are spatially and temporally (interannual, seasonal) variable, and there is little detailed information on drained nutrient-rich organic soils in the hemiboreal zone. We conducted a two-year study in drained peatland forests with different tree species Scots pine<em> </em>(<em>Pinus sylvestris</em>), Norway spruce (<em>Picea abies</em><em>), </em>birch<em> </em>(<em>Betula sp</em><em>.</em>), and black alder (<em>Alnus glutinosa</em>) and with various water levels and a natural wetland (fen) as a reference site in Estonia and Latvia from January 2021 to December 2022.</p><p>CH<sub>4</sub> and N<sub>2</sub>O fluxes were measured twice per month using the manual static chamber method. Environmental parameters in soil, such as groundwater level, temperature, and moisture were monitored and stored hourly by a data logger. Detailed studies of soil physio-chemical parameters and microbial community were conducted to relate greenhouse gas fluxes with environmental conditions.</p><p>Our preliminary results for the first year showed that all drained forest soils with low groundwater levels were annual methane sinks (−48.9 ± 12.9 μg m<sup>−‍2</sup> h<sup>−‍1</sup>), whereas the reference fen studied had a higher emission potential of 396 ± 214 μg m<sup>−‍2</sup> h<sup>−‍1</sup>. In contrast, birch and alder forests with poorly drained soils consumed less CH<sub>4</sub> and were annual emitters than artificially drained sites. Methane flux had a statistically significant correlation with water level and soil temperature. Most of the sites were annual emitters of N<sub>2</sub>O; wetter forest sites were higher emitters (21.0 ± 10.49 μg m<sup>−‍2</sup> h<sup>−‍1</sup>) than drier sites (17.97 ± 4.8 μg m<sup>−‍2</sup> h<sup>−‍1</sup>). Higher N<sub>2</sub>O emissions and temporal variability were associated with sites where water levels exhibited large seasonal fluctuations. N<sub>2</sub>O flux was controlled by soil temperature and moisture content, and emission peaks occurred in spring (freeze-thaw period).</p><p>This research was supported by the LIFE programme project "Demonstration of climate change mitigation potential of nutrients rich organic soils in the Baltic States and Finland", (2019-2023, LIFE OrgBalt, LIFE18 274CCM/LV/001158).</p>
To evaluate the potential of establishing a deciduous tree plantation on an industrial cutaway pe... more To evaluate the potential of establishing a deciduous tree plantation on an industrial cutaway peatland over an 8 ha large experimental site was established in the central part of Latvia and silver birch (Betula pendula Roth) and black alder (Alnus glutionsa (L.) Gaertn.) tree species were planted. As it is a harsh and unfavorable environment wood ash, otherwise a waste product, was used as a fertiliser and liming material in three applications (5, 10 and 15 t ha-1). In comparison with control, fertilised soils had higher Ca, Mg, P amounts, whilst the most substantial difference was seen in the amount of K. Application of wood ash also considerably increased soil pH from 3.5 (Control) to 5.9 (15 t ha-1). Even though showing reduced growth in unfertilised soil both alder and birch seedling survival rate was higher than 80%. The highest survival rate for birch was under wood ash treatment, while alder under 10 t ha-1 wood ash fertiliser treatment showed the lowest survival rate i.e. 81%. In total, more than 60 naturally occurring vegetation species were observed in the first and the second year of sites establishment after fertilisation. Species as Betula pendula, Betula pubescens, Populus tremula, Pinus sylvestris, Salix spp. often occurred from natural vegetation regeneration. Already after one year of vegetation succession increase in tree and shrub species cover was observed, suggesting perhaps such areas can be naturally afforested thus creating a more heterogeneous forest stand. In such a way sustaining economic use of land resources after peat extraction while providing other ecosystem services.
The study represents results on remote sensing methods based evaluation of land use and land use ... more The study represents results on remote sensing methods based evaluation of land use and land use changes in former and existing peat extraction areas in Latvia. The aim of the study is to elaborate activity data set for the National GHG inventory for the wetlands remaining wetlands for peat extraction. The study results provide sufficient data for application of the default emission factors for the peat extraction sites and flooded lands. Abandoned peat extraction fields, which are not yet afforested, flooded or rewetted should be reported as peat extraction sites following a conservative approach in application of the emission factors. The study results can be used to report land use changes since 1990; however, linearized approach in calculation of the land use change may result in overestimation or underestimation of GHG emissions in certain periods of time. According to study results, the area of peat extraction sites is considerably bigger than currently reported in the National GHG inventory, mainly due to considerable areas of abandoned peat extraction fields. Flooded lands may be a significant source of emissions and should be introduced in the National GHG inventory to secure consistency of reporting. Methodology for calculation of GHG emissions from flooded lands should be also elaborated. It is also necessary to elaborate emission factors for fertile and nonfertile peat extraction sites and continue work on separation of different soils in the inventory to increase accuracy of calculations.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
According to general knowledge rewetting of drained organic soils is a measure that can reduce ne... more 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.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Peer reviewed publications were used as the data source. Original data collection in the publicat... more Peer reviewed publications were used as the data source. Original data collection in the publications was by (i) inventories integrating change in soil C-stock, and (ii) CO2 monitoring fluxes by (a) chamber technique and/or (b) by eddy covariance technique. All CH4 and N2O fluxes monitored between soil and the atmosphere were by the chamber technique. Basic criteria for CO2, CO2-C, CH4 and N2O data inclusion to the database was: for soil inventory studies, estimate on soil C stock change averaging change over specified period of years was attainable, for eddy covariance studies, at least one annual soil CO2 balance estimate was attainable, for chamber studies, at least one annual soil CO2 balance estimate was attainable, for chamber studies, at least one annual or warm season soil total or soil heterotrophic cumulative CO2 emission estimate with potential to form respective annual soil CO2 balance estimate by using existing supplementary site-specific or site-type specific data was attainable, at least one annual soil CH4 balance or warm season cumulative soil CH4 flux estimate was attainable, at least one annual soil N2O balance or warm season cumulative soil N2O flux estimate was attainable. Annual soil CO2 balance estimates based on soil inventories were added into the database 'as is' basis. CO2 flux monitoring data based on chamber techniques usually necessitated further processing (e.g., measures on litter production and decomposition rates, evaluation of flux contributions from root respiration and/or ground vegetation dark respiration) before the estimate quantified soil CO2 balance. Such site specific or site-type specific supplementary data were collated from the relevant literature, authors and other specialists, and incorporated to CO2 flux data (applied changes are listed in Table S1-1 and in Data repository). Forming annual soil CH4 and N2O balance estimates in the data was less complicated because annualization was the only supplementary measure implemented to the estimates reported as cumulative warm season flux. Annualization. For studies providing GHG flux estimate based on warm season measurements, we used coefficient to supplement relative cold season fluxes. As in IPCC (2014), this was be made by adding flux-proportion of colder period GHG flux estimate which was based on the cold season (winter) measurements and flux estimates in boreal and subarctic peatlands. The values based on cold season flux proportion provided in Dise (1992), Alm et al. (1999), Aurela et al. (2002), Kim et al. (2007) and Leppälä et al. (2011). As the annualization coefficients we topped seasonal GHG flux estimate by 15.9% for CO2, by 16.7% for CH4, and 21.4% for N2O. Applied changes are listed in Table S1-1 and Table S1-2. Root respiration subtraction from the total respiration. Likely the largest and most coherent database providing both site type specific soil total (Rtot) and proportioned heterotrophic (Rhet) CO2 emissions in drained organic soils is analysed in Ojanen et al. (2010), and the database was available for our analyses. We split flux data from Ojanen et al. (2010) into ombrotrophic (n= 12) and minerotrophic (n= 53) site types and tested linear regression between CO2tot that includes autotrophic respiration of tree root systems and CO2het from soil. The analysis resulted in following linear regressions (95% confidence limits) for heterotrophic CO2het emission: emission = 1.1 + 0.39 × Rtot (R 2 = 0.641, SEmodel = 139, SEcoefficient = 183) for ombrotrophic sites and emission =-1.55 + 0.52 × Rtot (R 2 = 0.723, SEmodel = 217, SEcoefficient = 124) for minerotrophic sites. These equations were applied to form CO2het from the provided CO2tot estimates in data where CO2het was not readily available, and these estimates are listed in Table S1-1. Litter production and decomposition rates. Applied changes and data sources are shown in Table S1-1. Relative data reliability weighting. We determined a weigh for each annual soil GHG balance estimate formed from closed chamber data on the basis of estimate relative reliability (i.e. 1= no major issues
Flooded Land is defined as water bodies where human activities have caused changes in the amount ... more Flooded Land is defined as water bodies where human activities have caused changes in the amount of surface area covered by water, typically through water level regulation. Former peat extraction fields are a type of flooded lands which are often mentioned as significant source of greenhouse gas (GHG) emissions. In Latvia, the area of flooded lands in former peat extraction fields is 5.3 kha. The aim of the study is to evaluate GHG emissions from flooded former peat extraction fields to define that the flooded lands are the key source of GHG emissions and approve that further studies are necessary to elaborate country specific emission factors. The study is implemented in three areas in central part of the country, where peat extraction was stopped 25-35 years ago. Measures continued for 12 months, in 9 subplots, each was represented by 3 measurement points. Water and air temperature, as well as water level was measured during the study. According to the study results, flooded areas are a significant source of CO 2 emissions (967±107 kg CO 2-C ha-1 yr-1); however, the most significant agent of GHG emissions in flooded areas is methane (CH 4)-435±98 kg CH 4-C kg ha-1 yr-1. Flooded areas are not significant source of nitrous oxide (N 2 O) emissions. The net emissions from flooded areas are 18.1±3.7 tons CO 2 eq ha-1 yr-1. According to the study results, flooded lands are a significant (one of the largest) source of emissions, and further studies are necessary to improve GHG modelling solutions and activity data.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
The aim of the study is to evaluate greenhouse gas (GHG) fluxes from stems in black alder (Alnus ... more The aim of the study is to evaluate greenhouse gas (GHG) fluxes from stems in black alder (Alnus glutinosa (L.) Gaertn.) and birch (Betula pendula Roth) stands with drained and naturally wet nutrient rich peat soils, as well as to evaluate correlation between the GHG fluxes, soil temperature and groundwater level. The study was implemented in 8 forest standsthree black alder stands with nutrient rich peat soil (stand types according to national classification-Dryopterioso-caricosa and Filipendulosa) and 5 birch stands with peat soil (stand type Oxalidosa turf. mel. and Dryopterioso-caricosa). Measurement of GHG fluxes was continued for 12 months using Gasmet DX4040 FTIR analyser and removable non-transparent chambers of fixed volume and area. GHG fluxes were measured at 0.5, 1.0 and 1.5 m height on 3 trees in every stand. According to the study results the average CH4 emissions from stem surface in birch stands are 6.9 ± 6.2 g CO2 eq m-2 •yr-1 and in black alder stands 1.0 ± 3.2 g CO2 eq m-2 •yr-1. Groundwater level significantly effects CH4 emissionsif it remains above 15 cm during summer, the CH4 emissions from stem increases to 84.0 ± 25.2 g CO2 eq. m-2 •yr-1. Tree stems in drained peat soils are not a source of CH4 emissions. According to the study results tree stems in peat soils are not producing N2O emissions.
20th International Scientific Conference Engineering for Rural Development Proceedings, May 27, 2021
The study compares 9 forest management scenarios in birch plantations in cropland and grassland w... more The study compares 9 forest management scenarios in birch plantations in cropland and grassland with mineral and organic soils. Calculation period is 40 years for all scenarios. The study proves that establishment of birch plantations leads to reduction of greenhouse gas (GHG) emissions by 317-1776 tons of CO2 eq. ha-1 or 7.9-44.4 tons of CO2 eq. ha-1 per year. The reduction of GHG emissions in birch plantations is significantly influenced by growth conditionsin organic soils GHG emission reduction is 6 times higher than in mineral soils. In plantations with mineral soils most of the GHG emission reductions occur during 40 years after the establishment. In organic soils GHG emission reduction continues steadily due to reduction in GHG emissions from soils compared to alternative management scenarios (grassland or cropland). Harvested wood products and the substitution effect of biofuels play an important role in reducing GHG emissions, in particular through the assumption that wood products are recycled into biofuels at the end of their useful life. Recommended type of soil preparation in the most cases is mounding, but taking into account soil scarification costs, the number of target trees in the plantation must be reduced (down to 1500 per ha-1). Early tending, felling of young stands and regenerative felling must also be adapted to growing conditions by managing more intensively areas with fertile soils and less intensivelyplantations with poor soils. In more fertile soils higher planting density may increase CO2 removals in the middle term. When planting 1500-2000 seedlings ha-1 , moderately fertile soils ensures higher CO2 removals. According to the study results establishment of birch plantations in farmland is one of the most effective solutions for reducing GHG emissions in the land use, land use change and forestry (LULUCF), as well as in agriculture sector, especially, if organic soils are afforested.
Forest mineral soil is one of the terrestrial carbon pools, and changes in forest management prac... more Forest mineral soil is one of the terrestrial carbon pools, and changes in forest management practices can affect the carbon stock in forest soil. The purpose of the study is to estimate temporal fertilization impact on mineral soil organic carbon stock, depending on fertilizers applied, forest stand type, different dominant tree species of the stands. Coniferous and birch forest stands with mineral soil in the central and eastern part of Latvia were selected for the experiment. The fertilizers used were wood ash and nitrogen containing mineral fertilizer. No significant differences in organic carbon stock in O horizon were detected 2-5 years after fertilization. A tendency of smaller organic carbon stock in upper mineral soil layers (0-10 cm, 10-20 cm) was found in most part of objects. Significantly smaller organic carbon stock was found in upper mineral soil layers (0-10 cm and 10-20 cm) in birch stands with wet mineral soil treated with ammonium nitrate if compared to the control plots, possibly due to a different soil moisture regime of forest stands. The positive and significant correlations between soil organic carbon and nitrogen stocks were found in most part of the objects.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
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