Sirvi Autor "Soosaar, Kaido" järgi

Nüüd näidatakse 1 - 20 22

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Distinct microbial communities drive methane cycling in below- and above-ground compartments of tropical cloud forests growing on peat
(2025) Kazmi, Fahad Ali; Mander, Ülo; Khanongnuch, Ramita; Öpik, Maarja; Ranniku, Reti; Soosaar, Kaido; Masta, Mohit; Tenhovirta, Salla A. M.; Kasak, Kuno; Ah-Peng, Claudine; Espenberg, Mikk
Cloud forests are unique yet understudied ecosystems regarding CH4 exchange despite their significance in carbon storage. We investigated CH4 fluxes in peat soil and tree stems of two tropical cloud forests on Réunion Island, one featuring Erica reunionensis and the second a mix of E. reunionensis and Alsophila glaucifolia. The study examined microbiomes across below-ground (soil) and above-ground (canopy soil, leaves, and stems) forest compartments. Metagenomics and qPCR analyses targeted key genes in methanogenesis and methanotrophy in soil and above-ground samples, alongside soil physicochemical measurements. CH4 fluxes from peat soil and tree stems were measured using gas chromatography and portable trace gas analyzers. Peat soil in both forests acted as a CH4 sink (− 23.8 ± 4.84 µg C m− 2 h− 1) and CO2 source (55.5 ± 5.51 µg C m− 2 h− 1), with higher CH4 uptake in sites dominated by endemic tree species E. reunionensis. In forest soils, a high abundance of n-DAMO 16 S rRNA gene (3.42 × 107 ± 7 × 106 copies/g dw) was associated with nitrate levels and higher rates of CH4 uptake and CO2 emissions. NC-10 bacteria (0.1–0.3%) were detected in only the Erica forest soil, verrucomicrobial methanotrophs (0.1–3.1%) only in the mixed forest soil, whereas alphaproteobacterial methanotrophs (0.1–3.3%) were present in all soils. Tree stems in both forests were weak sinks of CH4 (-0.94 ± 0.4 µg C m− 2 h− 1). The canopy soil hosted verrucomicrobial methanotrophs (0.1–0.3%). The leaves in both forests exhibited metabolic potential for CH4 production, e.g., exhibiting high mcrA copy numbers (3.5 × 105 ± 2.3 × 105 copies/g dw). However, no CH4-cycling functional genes were detected in the stem core samples. Tropical cloud forest peat soils showed high anaerobic methanotrophy via the n-DAMO process, while aerobic methanotrophs were abundant in canopy soils. Leaves hosted methanotrophs but predominantly methanogens. These results highlight the significant differences between canopy and soil microbiomes in the CH4 cycle, emphasizing the importance of above-ground microbiomes in forest CH4 gas budgets.
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Dry and wet periods determine stem and soil greenhouse gas fluxes in a northern drained peatland forest
(Science of The Total Environment, 2024) Ranniku, Reti; Mander, Ülo; Escuer-Gatius, Jordi; Schindler, Thomas; Kupper, Priit; Sellin, Arne; Soosaar, Kaido
Greenhouse gas (GHG) fluxes from peatland soils are relatively well studied, whereas tree stem fluxes have received far less attention. Simultaneous year-long measurements of soil and tree stem GHG fluxes in northern peatland forests are scarce, as previous studies have primarily focused on the growing season. We determined the seasonal dynamics of tree stem and soil CH4, N2O and CO2 fluxes in a hemiboreal drained peatland forest. Gas samples for flux calculations were manually collected from chambers at different heights on Downy Birch (Betula pubescens) and Norway Spruce (Picea abies) trees (November 2020–December 2021) and analysed using gas chromatography. Environmental parameters were measured simultaneously with fluxes and xylem sap flow was recorded during the growing season. Birch stems played a greater role in the annual GHG dynamics than spruce stems. Birch stems were net annual CH4, N2O and CO2 sources, while spruce stems constituted a CH4 and CO2 source but a N2O sink. Soil was a net CO2 and N2O source, but a sink of CH4. Temporal dynamics of stem CH4 and N2O fluxes were driven by isolated emissions' peaks that contributed significantly to net annual fluxes. Stem CO2 efflux followed a seasonal trend coinciding with tree growth phenology. Stem CH4 dynamics were significantly affected by the changes between wetter and drier periods, while N2O was more influenced by short-term changes in soil hydrologic conditions. We showed that CH4 emitted from tree stems during the wetter period can offset nearly half of the soil sink capacity. We presented for the first time the relationship between tree stem GHG fluxes and sap flow in a peatland forest. The net CH4 flux was likely an aggregate of soil-derived and stem-produced CH4. A dominating soil source was more evident for stem N2O fluxes.
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Effects of Water Table Fluctuation on Greenhouse Gas Emissions from Wetland Soils in the Peruvian Amazon
(2021) Pärn, Jaan; Soosaar, Kaido; Schindler, Thomas; Machacova, Katerina; Muñoz, Waldemar Alegría; Fachín, Lizardo; Aspajo, José Luis Jibaja; Negron‑Juarez, Robinson I.; Maddison, Martin; Rengifo, Jhon; Dinis, Danika Journeth Garay; Oversluijs, Adriana Gabriela Arista; Fucos, Manuel Calixto Ávila; Vásquez, Rafael Chávez; Wampuch, Ronald Huaje; García, Edgar Peas; Sohar, Kristina; Horna, Segundo Cordova; Gómez, Tedi Pacheco; Muñoz, Jose David Urquiza; Espinoza, Rodil Tello; Mander, Ülo
Amazonian swamp forests remove large amounts of carbon dioxide (CO2) but produce methane (CH4). Both are important greenhouse gases (GHG). Drought and cultivation cut the CH4 emissions but may release CO2. Varying oxygen content in nitrogen-rich soil produces nitrous oxide (N2O), which is the third most important GHG. Despite the potentially tremendous changes, GHG emissions from wetland soils under different land uses and environmental conditions have rarely been compared in the Amazon. We measured environmental characteristics, and CO2, CH4 and N2O emissions from the soil surface with manual opaque chambers in three sites near Iquitos, Peru from September 2019 to March 2020: a pristine peat swamp forest, a young forest and a slash-and-burn manioc field. The manioc field showed moderate soil respiration and N2O emission. The peat swamp forests under slight water table drawdown emitted large amounts of CO2 and CH4. A heavy post-drought shower created a hot moment of N2O in the pristine swamp forest, likely produced by nitrifiers. All in all, even small changes in soil moisture can create hot moments of GHG emissions from Amazonian wetland soils, and should therefore be carefully monitored.
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Estimating hemi-boreal forest productivity with a process-based BEPS model and multi-source Earth Observation data
(Tartu Ülikool, 2021) Harun, Fariha; Soosaar, Kaido; Pisek, Jan; Tartu Ülikool. Geograafia osakond; Tartu Ülikool. Loodus- ja täppisteaduste valdkond
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Greenhouse gas emissions from ditches in oil palm plantations on tropical peatlands in Malaysia
(2025) Kasak, Kuno; Dronova, Iryna; Soosaar, Kaido; Melling, Lulie; Xhuan, Wong Guan; Sangok, Faustina; Ranniku, Reti; Villa, Jorge A.; Bansal, Sheel; Peacock, Michael; Mander, Ülo
Tropical peatlands, which store 20% of global peat carbon, are increasingly threatened by conversion to alternative land-uses such as oil palm plantations, pulp wood plantations, crop growth or other economic activities. This transformation involves peatland drainage, which lowers water tables, exposes peat to oxygen, and alters greenhouse gas (GHG) emissions: increasing carbon dioxide (CO2) and nitrous oxide (N2O) fluxes while reducing methane (CH4) emissions from soils. However, drainage ditches created in the process may become significant sources of CH4 due to anoxic conditions. This study quantified GHG fluxes from drainage ditches in Sarawak, Malaysia, through spatial sampling conducted during the daytime in the transitional period between the drier and wetter seasons using portable trace gas analyzers. Median fluxes were 0.19 g CH4 m−2 d−1, 17.1 g CO2 m−2 d−1, and − 0.12 mg N2O m−2 d−1. Physical water parameters such as pH, oxygen concentration, temperature, and oxidation–reduction potential were found to be significant drivers of GHG fluxes. The median emissions from ditches in one hectare of land were 5.84 kg CO2 ha−1 d−1, 2.78 kg CH4 as CO2 eq ha−1 d−1, and − 0.001 kg N2O as CO2 eq ha−1 d−1. These findings underscore the role of drainage ditches as CH4 sources in tropical peatland agriculture, highlighting the need for further research into GHG management in these modified landscapes.
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Greenhouse gas fluxes in rural landscapes of Estonia
(2010-11-23) Soosaar, Kaido
Kasvuhoonegaase on maailmas väga põhjalikult uuritud. Käesolev doktoritöö sisaldab 165 ISI Web of Science andmebaasis publitseeritud artiklite kirjanduslikku ülevaadet ja laiamahulist uurimustööd, mille raames mõõdeti Eestis CH4, N2O ja CO2 emissioone 14 erinevalt maakasutusega alalt . Kirjanduse analüüsi tulemused näitavad, et suurimad metaani emissioonid leiti looduslikelt märgaladelt (106 kg CH4-C ha–1 yr–1). Suurimad lämmastikoksiidi mediaanväärtused leiti kuivendatud (osaliselt taastatud) turbaaladelt ja lammialadelt (vastavalt 7,2 ja 6,5 kg N2O-N ha-1 a-1), millele järgnesid hüdromorfsed põllumaad (4,5 kg N2O-N ha-1 a-1), väetatud heinamaad (4,2-4,7 kg N2O-N ha-1 a-1) ja hüdromorfsed lehtpuumetsad (3,8 kg N2O-N ha–1 a–1). Kõigi kolme mõõdetud kasvuhoonegaaside emissioonid näitasid nii ruumilist kui ka ajalist varieeruvust ning erinevusi vastavalt keskkonnatingimustele. Suurimad CH4 mediaanväärtused määrati hüdromorfsetes kaldaäärsetes metsamuldades ning kuivendatud siirdesoo heinamaa muldades. Kõrgeimad N2O emissioonid tekkisid väetatud autotroofsetel põllumuldadel, automorfsetel kaldaäärsetel metsamuldadel ning kuivendatud siirdesoo metsamuldadel. Suurimad CO2 aastased mediaanväärtused olid automorfsetel söötis maa ja heinamaa muldadel. Kui CO2 ja CH4 emissioonid näitasid uurimisaladel erinevusi vastavalt aastaaegadele, siis dilämmastikoksiidi emiteerimisel ei leitud selgelt ajalist trendi. CO2 emissioonide puhul leiti tugev korrelatsioon (kõikidel uurimisaladel¸ R2=0,72) mulla temperatuuriga, seega emissioonid olid suuremad suveperioodil. CH4 puhul ilmnes erinevus auto- ja hüdromorfsete muldade vahel, mil esimesed olid eelkõige metaani sidujad ning hüdromorfsed mullad emiteerijad. Viiratsi ja Porijõe kaldaäärsete kaitsevööndite puhul leiti tugevad seosed mõõdetud gaaside ja keskmise kuu temperatuuri ning CH4 emissiooni ja kuu sademete hulga vahel. Samuti, kui veetase on väiksem kui 20 cm maapinnast, siis CH4 emissioon suurenes ja N2O ja CO2 vähenes. Reovee järelpuhastina kasutavast pilliroostikust saadud tulemused näitasid, et keskmised N2O emissioonid olid suhteliselt madalad, varieerudes –5,0 to 3,7 μg N2O m–2 h–1. CH4 emissioonide puhul ilmnesid suured ajalis-ruumilised erinevused, kus suurimad väärtused olid sissevoolus. Keskmised CO2 emissioonid roostikust varieerusid 14,3 to 334 mg CO2-C m–2 h–1.
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Importance of N2O in greenhouse gas budgets of tropical peatlands
(Frontiers in Environmental Science, 2025) Pärn, Jaan; Espenberg, Mikk; Soosaar, Kaido; Kasak, Kuno; Thayamkottu, Sandeep; Schindler, Thomas; Ranniku, Reti; Sohar, Kristina; Mander, Ülo; Melling, Lulie; Malaverri, Lizardo Fachín
Tropical peatland ecosystems significantly influence Earth’s climate through their greenhouse gas exchange. Permanently wet peatlands take up carbon dioxide in plants and accumulate organic carbon in soil but release methane. Man-made drainage of peat releases carbon dioxide and nitrous oxide. Exchange of the greenhouse gases in relationship with tropical conditions are poorly understood. This is a global-scale field study of fluxes of three greenhouse gases – carbon dioxide, methane and nitrous oxide – and their environmental drivers across the full moisture range of tropical peatlands. We show that net emission of carbon dioxide dominates greenhouse gas budgets in drained tropical peatlands while nitrous oxide emission is the second most important contributor. Tropical peat swamp forests in their natural wet states are large greenhouse gas sinks and should be a global conservation and restoration priority.
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Interactions of fertilisation and crop productivity in soil nitrogen cycle microbiome and gas emissions
(2025) Kuusemets, Laura; Mander, Ülo; Escuer-Gatius, Jordi; Astover, Alar; Kauer, Karin; Soosaar, Kaido; Espenberg, Mikk
Fertilised soils are a significant source of nitrous oxide (N2O), a highly active greenhouse gas and a stratospheric ozone depleter. Nitrogen (N) fertilisers, while boosting crop yield, also lead to N2O emissions into the atmosphere, impacting global warming. We investigated relationships between mineral N fertilisation rates and additional manure amendment with different crop types through the analysis of abundances of N cycle functional genes, soil N2O and N2 emissions, nitrogen use efficiency (NUE), soil physicochemical analysis and biomass production. Our study indicates that N2O emissions are predominantly dependent on the mineral N fertilisation rate and enhance with an increased mineral N fertilisation rate. Crop type also has a significant impact on soil N2O emissions. Higher N2O emissions were attained with the application of manure in comparison to mineral fertilisation. Manure amendment also increased the number of N cycle genes that are significant in the variations of N2O. The study indicates that N2O emissions were mainly related to nitrification in the soil. Quantification of nitrogen cycle functional genes also showed the potential role of denitrification, comammox (complete ammonia oxidation) and dissimilatory nitrate reduction to ammonium (DNRA) processes as a source of N2O. Our study did not find soil moisture to be significantly linked to N2O emissions. The results of the study provide evidence that, for wheat, a fertilisation rate of 80 kg N ha−1 is closest to the optimal rate for balancing biomass yield and N2O emissions and achieving a high NUE. Sorghum showed good potential for cultivation in temperate climates, as it showed a similar biomass yield compared to the other crop types and fertilisation rates but maintained low N2O emissions and N losses in a mineral N fertilisation rate of 80 kg N ha−1.
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Kasvuhoonegaaside vood kuivendatud siirdesoo- ja rabametsa muldadest
(Tartu Ülikool, 2023) Truupõld, Joosep; Soosaar, Kaido; Ranniku, Reti; Tartu Ülikool. Geograafia osakond; Tartu Ülikool. Loodus- ja täppisteaduste valdkond
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Kaugküttega liitumise valmidus Tartu linna näitel
(Tartu Ülikool, 2021) Karu, Helena; Soosaar, Kaido; Külaots, Margo; Tartu Ülikool. Geograafia osakond; Tartu Ülikool. Loodus- ja täppisteaduste valdkond
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Long-term carbon sequestration and heatwave resilience in an old hemiboreal upland coniferous forest
(Agricultural and Forest Meteorology, 2025) Rogozin, Svyatoslav; Krasnova, Alisa; Mander, Ülo; Uri, Veiko; Soosaar, Kaido
Boreal forests play an important role in the global carbon cycle due to their extensive area and ability to sequester a considerable amount of atmospheric carbon dioxide (CO2). They are generally stable ecosystems that function as carbon sinks. However, their sink capacity is vulnerable to the impact of extreme weather conditions. In this study, we aim to investigate the multi-year and seasonal carbon dynamics of an old upland coniferous forest in the hemiboreal zone, identify the main environmental drivers influencing annual NEP, and explore the potential legacy effects of the 2018 heatwave. Over an eight-year period (2016–2023), the forest shifted from a carbon sink (mean net ecosystem productivity (NEP) of 238 ± 52 g C m−2 year−1) to a carbon-neutral state in 2020 (NEP = -2 ± 5 g C m−2 year−1) and back to a net carbon sink (NEP = 136 ± 50 g C m−2 year−1). The average NEP over the eight-year period was 170 ± 42 g C m−2 year−1. Our research showed no significant year-to-year changes in GEP during the study period, while the changes in Reco were substantial. Our results confirm that air temperature has the greatest influence on annual NEP. The warmest autumn over the past 19 years, recorded in 2020, and an atypical June together resulted in a noticeable increase in ecosystem respiration, which shifted annual NEP towards negative net values, while no significant impact on GEP was found. Additionally, our study found that the old upland hemiboreal forest showed no legacy effect in the years following the 2018 heatwave, demonstrating its resilience to extreme temperature events. Our results underscore the importance of continuous monitoring carbon dynamics variability to determine the ecosystem's resilience to seasonal temperature fluctuations and to inform management strategies for forests preservation.
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Mature riparian alder forest acts as a strong and consistent carbon sink
(2025) Krasnova, Alisa; Soosaar, Kaido; Rogozin, Svyatoslav; Krasnov, Dmitrii; Mander, Ülo
Alder forests are widely spread across Northern Hemisphere, frequently occupying riparian buffer zones and playing a key role in enhancing soil fertility through symbiosis with nitrogen-fixing bacteria. Despite their ecological significance, studies on carbon (C) and water (H2O) exchange in alder forests remain scarce, particularly in the context of hydroclimatic variability and extreme weather events. In this study, we used eddy-covariance flux measurements from three contrasting years to assess the C balance and H2O exchange of a mature riparian grey alder forest in the hemiboreal zone in Estonia. The site was a strong and consistent carbon sink with annual net ecosystem exchange (NEE) ranging from -496 to -663 g C m⁻² y⁻¹, gross primary production (GPP) from -1258 to -1420 g C m⁻² y⁻¹ and ecosystem respiration (ER) from 595 to 923 g C m⁻² y⁻¹. Evapotranspiration (ET) varied from 194 to 342 kg H2O m⁻² y⁻¹ and ecosystem water use efficiency (EWUE) was 4.2 – 6.5 g C kg H2O-1. The drought and heatwave year (2018) featured the highest net carbon uptake, driven by an increase in GPP during spring and a reduction in ER during late summer and autumn. A minor impact of drought on GPP combined with a 35 % reduction in ET in 2018 lead to peak values of EWUE in response to H2O limitation. In 2019, we found no evidence of a short-term drought legacy effect, as carbon exchange components recovered to the 2017 levels and ET was the highest out of years. Given that this forest is beyond the typical harvestable age, its strong and consistent carbon sequestration, combined with high short-term resilience, provides valuable insights for sustainable forest management. These findings highlight the potential of riparian grey alder forests to maintain productivity under hydroclimatic variability, reinforcing their role in regional carbon cycling as a part of natural climate mitigation solutions.
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Metaanivood Soontaga metsaökosüsteemi uurimisjaamas aastatel 2013–2019
(Tartu Ülikool, 2020) Univer, Marie Johanna; Soosaar, Kaido; Tartu Ülikool. Geograafia osakond; Tartu Ülikool. Loodus- ja täppisteaduste valdkond
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Nitrogen cycling genes abundance in soil and aboveground compartments of tropical peatland cloud forests and a wetland on Réunion Island
(Scientific Reports, 2025) Kazmi, Fahad Ali; Mander, Ülo; Ranniku, Reti; Öpik, Maarja; Püssa, Kersti; Soosaar, Kaido; Kasak, Kuno; Masta, Mohit; Ah-Peng, Claudine; Espenberg, Mikk
Peatland cloud forests, characterized by high altitude and humidity, are among the least-studied tropical ecosystems despite their significance for endemism and the bioavailable nitrogen (N) that can be emitted as N2O. While research has mainly focused on soil, the above-ground microbial N cycle remains largely unexplored. We quantified microbial N cycling genes across ecosystem compartments (soil, canopy soil, tree stems, and leaves) in relation to N2O and N2 fluxes and soil physicochemical properties in two peatland cloud forests and a wetland on Réunion Island. Complete denitrification minimized N2O emissions and increased N2 fluxes in wetland soils. In cloud forest soils, archaeal nitrification primarily produced nitrate (NO3–), while low pH potentially slowed denitrification, resulting in minimal N2O emissions. Soil N-fixers were more abundant in Erica reunionensis-dominated forests than in mixed forests. Tree stems varied between weak N2O sinks and sources, with fluxes unrelated to gene abundances in stems. High prokaryotic and fungal nirK gene abundance in forest canopy soil suggests potential for above-ground denitrification in wet conditions. nosZ-I genes found in forest canopy soil and leaves (E. reunionensis, Alsophila glaucifolia, and Typha domingensis) indicate that plants, including forest canopy, may play a significant role in the reduction of N2O.
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Puutüvede N20 ja CH4-vood kuivendatud kõdusoo segametsast
(Tartu Ülikool, 2021) Lehtme, Eliisa; Soosaar, Kaido; Ranniku, Reti; Tartu Ülikool. Geograafia osakond; Tartu Ülikool. Loodus- ja täppisteaduste valdkond
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Raskmetallid hundinuiataimedes
(2006) Soosaar, Kaido; Mander, Ülo, juhendaja
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Relationships between Environmental Factors and the Growth of Above-Ground Biomass in Boreal Forest
(Tartu Ülikool, 2016) Ye, Xiaozhou; Soosaar, Kaido; Läänelaid, Alar; Tartu Ülikool. Loodus- ja täppisteaduste valdkond
This study investigates the influence of shortwave radiation (albedo is calculated to characterize the absorption of shortwave radiation), temperature and relative humidity on biomass growth of two coniferous species in boreal forest. Stem circumferences are measured for calculating daily biomass growth rate and calculated growth rate is analysed by statistical method for revealing its possible correlations to environmental factors (shortwave radiation, temperature and relative humidity). Comparisons between biomass growth rate and environmental factors are also made for finding correlation. Temperature sets lower limit for biomass growth. Biomass growth rate is found dependent on the values of albedo, meaning absorption of shortwave radiation dominates growth. Relative humidity is found negatively dependent on temperature. However, there is no statistical dependence of growth rate found on temperature and relative humidity, although some extreme temperatures and relative humidity are noticed affecting growth rate through evaporation (temperature affects negatively and relative humidity affects positively). The model on the relationship between values of albedo and temperature in the process of glucose absorption is also revealed and albedo is regarded to dominate such a process. Connections among these environmental factors are found and the affecting mechanism is established finally. Besides, species-specific difference of response to shortwave radiation between Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L.) is revealed.
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Reviews and syntheses: Greenhouse gas emissions from drained organic forest soils – synthesizing data for site-specific emission factors for boreal and cool temperate regions
(2023) Jauhiainen, Jyrki; Heikkinen, Juha; Clarke, Nicholas; He, Hongxing; Dalsgaard, Lise; Minkkinen, Kari; Ojanen, Paavo; Vesterdal, Lars; Alm, Jukka; Butlers, Aldis; Callesen, Ingeborg; Jordan, Sabine; Lohila, Annalea; Mander, Ülo; Óskarsson, Hlynur; Sigurdsson, Bjarni D.; Søgaard, Gunnhild; Soosaar, Kaido; Kasimir, Åsa; Bjarnadottir, Brynhildur; Lazdins, Andis; Laiho, Raija
We compiled published peer-reviewed CO2, CH4, and N2O data on managed drained organic forest soils in boreal and temperate zones to revisit the current Tier 1 default emission factors (EFs) provided in the IPCC (2014) Wetlands Supplement: to see whether their uncertainty may be reduced; to evaluate possibilities for breaking the broad categories used for the IPCC EFs into more site-type-specific ones; and to inspect the potential relevance of a number of environmental variables for predicting the annual soil greenhouse gas (GHG) balances, on which the EFs are based. Despite a considerable number of publications applicable for compiling EFs being added, only modest changes were found compared to the Tier 1 default EFs. However, the more specific site type categories generated in this study showed narrower confidence intervals compared to the default categories. Overall, the highest CO2 EFs were found for temperate afforested agricultural lands and boreal forestry-drained sites with very low tree stand productivity. The highest CH4 EFs in turn prevailed in boreal nutrient-poor forests with very low tree stand productivity and temperate forests irrespective of nutrient status, while the EFs for afforested sites were low or showed a sink function. The highest N2O EFs were found for afforested agricultural lands and forestry-drained nutrient-rich sites. The occasional wide confidence intervals could be mainly explained by single or a few highly deviating estimates rather than the broadness of the categories applied. Our EFs for the novel categories were further supported by the statistical models connecting the annual soil GHG balances to site-specific soil nutrient status indicators, tree stand characteristics, and temperature-associated weather and climate variables. The results of this synthesis have important implications for EF revisions and national emission reporting, e.g. by the use of different categories for afforested sites and forestry-drained sites, and more specific site productivity categories based on timber production potential.
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Soil moisture and microbiome explain greenhouse gas exchange in global peatlands
(Scientific Reports, 2025) Pärn, Jaan; Thayamkottu, Sandeep; Öpik, Maarja; Bahram, Mohammad; Tedersoo, Leho; Espenberg, Mikk; Davison, John Alexander; Kasak, Kuno; Maddison, Martin; Niinemets, Ülo; Ostonen, Ivika; Soosaar, Kaido; Sohar, Kristina; Zobel, Martin; Mander, Ülo
Earth's climate is tightly connected to carbon and nitrogen exchange between the atmosphere and ecosystems. Wet peatland ecosystems take up carbon dioxide in plants and accumulate organic carbon in soil but release methane. Man-made drainage releases carbon dioxide and nitrous oxide from peat soils. Carbon and nitrous gas exchange and their relationships with environmental conditions are poorly understood. Here, we show that open peatlands in both their wet and dry extremes are greenhouse gas sinks while peat carbon/nitrogen ratios are high and prokaryotic (bacterial and archaeal) abundances are low. Conversely, peatlands with moderate soil moisture levels emit carbon dioxide and nitrous oxide, while prokaryotic abundances are high. The results challenge the current assumption of a uniform effect of drainage on greenhouse gas emissions and show that the peat microbiome of greenhouse-gas sources differs fundamentally from sinks.
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Springtime soil and tree stem greenhouse gas fluxes and the related soil microbiome pattern in a drained peatland forest
(2025) Ranniku, Reti; Kazmi, Fahad Ali; Espenberg, Mikk; Truupõld, Joosep; Escuer‑Gatius, Jordi; Mander, Ülo; Soosaar, Kaido
Spring can be a critical time of year for stem and soil methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) emissions as soil freeze–thaw events can be hot moments of gas release. Greenhouse gas fluxes from soil, Downy birch (Betula pubescens) and Norway spruce (Picea abies) stems were quantified using chamber systems and gas analysers in spring 2023 in a northern drained peatland forest. Dissolved gas concentrations in birch sap and soil water, environmental parameters, soil chemistry, and functional gene abundances in the soil were determined. During spring, initially low soil and stem CH4, N2O, and CO2 emissions increased towards late April. Temperature emerged as the primary driver of soil and stem fluxes, alongside photosynthetically active radiation influencing stem fluxes. Soil hydrologic conditions had minimal short-term impact. No clear evidence linked stem CH4 emissions to birch sap gas concentrations, while relationships existed for CO2. Functional gene abundances of the N and CH4-cycles changed between measurement days. Potential for methanogenesis and complete denitrification was higher under elevated soil water content, shifting to methanotrophy and incomplete denitrification as the study progressed. However, our results highlight the need for further analysis of relationships between microbial cycles and GHG fluxes under different environmental conditions, including identifying soil microbial processes in soil layers where tree roots absorb water.