Sirvi Autor "Kasak, Kuno" järgi

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15N tracers and microbial analyses reveal in situ N2O sources in contrasting water regimes of a drained peatland forest
(2024) Masta, Mohit; Espenberg, Mikk; Kuusemets, Laura; Pärn, Jaan; Thayamkottu, Sandeep; Sepp, Holar; Kirsimäe, Kalle; Sgouridis, Fotis; Kasak, Kuno; Soosaar, Kaido; Mander, Ülo
Managed peatlands are a significant source of nitrous oxide (N2O), a powerful greenhouse gas and stratospheric ozone depleter. Due to the complexity and diversity of microbial N2O processes, different methods such as tracer, isotopomer, and microbiological technologies are required to understand these processes. The combined application of different methods helps to precisely estimate these processes, which is crucial for the future management of drained peatlands, and to mitigate soil degradation and negative atmospheric impact. In this study, we investigated N2O sources by combining tracer, isotopomer, and microbial analysis in a drained peatland forest under flooded and drained treatments. On average, the nitrification genes showed higher abundances in the drained treatment, and the denitrification genes showed higher abundances in the flooded treatment. This is consistent with the underlying chemistry, as nitrification requires oxygen while denitrification is anaerobic. We observed significant differences in labelled N2O fluxes between the drained and flooded treatments. The emissions of N2O from the flooded treatment were nearly negligible, whereas the N2O evolved from the nitrogen-15 (15N)-labelled ammonium (15NH4+) in the drained treatment peaked at 147 μg 15N m-2 h-1. This initially suggested nitrification as the driving mechanism behind N2O fluxes in drained peatlands, but based on the genetic data, isotopic analysis, and N2O mass enrichment, we conclude that hybrid N2O formation involving ammonia oxidation was the main source of N2O emissions in the drained treatment. Based on the 15N-labelled nitrate (15NO3-) tracer addition and gene copy numbers, the low N2O emissions in the flooded treatment came possibly from complete denitrification producing inert dinitrogen. At atomic level, we observed selective enrichment of mass 45 of N2O molecule under 15NH4+ amendment in the drained treatment and enrichment of both masses 45 and 46 under 15NO3- amendment in the flooded treatment. The selective enrichment of mass 45 in the drained treatment indicated the presence of hybrid N2O formation, which was also supported by the high abundances of archaeal genes.
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Carbon dioxide dynamics across three stages of tropical peatland conversion to oil palm plantations
(2026) Kiew, Frankie; Hirata, Ryuichi; Hirano, Takashi; Wong, Guan Xhuan; Waili, Joseph Wenceslaus; Lo, Kim San; Soosaar, Kaido; Kasak, Kuno; Melling, Lulie; Mander, Ülo
This study represents the first long-term investigation spanning from a tropical peat swamp forest (PSF) to its conversion into an oil palm plantation (OPP), offering valuable data for assessing carbon dioxide (CO2) dynamics across different conversion stages. The conversion of tropical peat swamp forests to oil palm plantations has significant implications for CO2 dynamics. However, ecosystem-scale studies investigating CO2 dynamics across different stages of land conversion are lacking. This study used the eddy covariance (EC) technique to measure the net ecosystem exchange (NEE) of CO2 above a tropical peat swamp forest in Sarawak, Malaysia, from 2011 until it was cleared in 2017 and ultimately converted into an OPP in 2018. Our study found that the removal of forest biomass during land preparation led to a substantial increase in annual NEE from 25 ± 179 (2011 to 2016) to 2732 ± 655 g C m−2 year−1 (2017 to 2019). This increase was attributed to an 83 % reduction in gross primary productivity (GPP) and a 14 % reduction in ecosystem respiration (Reco). The near-ground environmental conditions also significantly changed across the conversion stages, inducing drier conditions compared to the forest. These changes were found to affect the controlling factors of nighttime NEE during conversion, resulting in a negative relationship with both air temperature and vapor pressure deficit above canopy, in contrast to the typical relationship with groundwater level observed before conversion. The conversion is also found to cause significant reduction in overall ecosystem photosynthetic activity as evidenced by the reduction in maximum gross photosynthetic rate (Pmax), photosynthetic photon flux density (PPFD), quantum yeild (α), and dark respiration (REd). Although ecosystem-scale assessments of CO2 dynamics provide insights into how ecosystems respond to changes in relation to land conversion, it is crucial to assess other respiration components, such as soil respiration and aboveground woody debris, for a more comprehensive analysis.
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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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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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Greenhouse gas emissions and water treatment efficiency in subsurface flow filters using various substrates
(2016-05-13) Kasak, Kuno; Mander, Ülo, juhendaja; Truu, Marika, juhendaja; Tartu Ülikool. Loodus- ja täppisteaduste valdkond.
Tehismärgalade ja pinnasfiltersüsteemide kasutamine reoveepuhastuseks on viimase paarikümne aastaga märkimisväärselt arenenud. Uute tehnoloogiate väljatöötamine on suurendanud nii reovee puhastusefektiivsust, kui ka vähendanud süsteemidest lenduvate kasvuhoonegaaside (KHG) hulka. Käesoleva doktoritöö peamiseks eesmärgiks oli uurida erinevate filtermaterjalide (liiv, kruus, kergkruus, turvas, hüdratiseerunud tuhaplatoo sete) mõju pinnasfiltersüsteemide puhastusefektiivsele hall- ning reovee puhastamisel ning analüüsida nende materjalide mõju KHG (CO2, CH4 ja N2O) emissioonile. Töö tulemused näitasid, et kergkruusal põhinevad filtermaterjalid (Filtralite) on sobilikud eeskätt just aeroobsete puhastusprotsesside läbiviimiseks vertikaalvoolulistes pinnasfiltrites, muutes nad sobilikuks lämmastikühendite ning orgaanika eemaldamiseks. Horisontaalvoolulistes kergkruusa, tuhaplatoosette ja turbafiltrites lämmastiku ja orgaanika eemaldamises märkimisväärseid tulemusi ei saavutatud. Küll aga näitas tuhaplatoo sete väga head fosforiärastamise efektiivsust nii hall- kui ka reoveest just horisontaalvoolulistes pinnasfiltrites. Sedavõrd head tulemused on tingitud peamiselt sellest, et tuhaplatoo sete sisaldab suurel hulgal reaktiivseid kaltsiumirikkaid mineraale, mis sadestuvad materjalis kaltsiumfosfaadina. KHG mõõtmised näitasid, et väikseimad emissioonid olid iseloomulikud peamiselt filtritele, kus oli kasutusel tuhaplatoo sete. Eriti madalad olid CO2 emissioonid võrreldes näiteks turba või tavapäraste filtermaterjalidega (liiv ja kruus). Madalate CO2 emissioonide peamiseks põhjuseks on samuti reaktiivsed kaltsiumimineraalid, mis reageerivad atmosfääri CO2-ga ning sadestavad selle kaltsiumkarbonaadi ehk kaltsiidina. Lisaks CO2 emissioonile olid oluliselt madalama ka CH4 ja N2O voog, olles tingitud peamiselt aluselisest ning sulfaadirikkast keskkonnast, mis ei ole sobilik metaani oksüdeerivatele ning denitrifitseerivatele bakteritele. Kokkuvõtvalt näitasid doktoritöö tulemused, et tuhaplatoo sete on sobilik alternatiivne filtermaterjal fosfori eemaldamiseks erinevatest reovetest väga madalate KHG-de emissiooniga. Tuhafiltrit on soovitatav kasutada reovee järelpuhastuses, sest orgaanika ning lämmastikuärastuses on ta väheefektiivne.
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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 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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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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Importance of N2O in greenhouse gas budgets of tropical peatlands
(2025) Pärn, Jaan; Espenberg, Mikk; Soosaar, Kaido; Kasak, Kuno; Thayamkottu, Sandeep; Schindler, Thomas; Ranniku, Reti; Sohar, Kristina; Malaverri, Lizardo Fachín; Melling, Lulie; Mander, Ülo
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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Modelling the nitrous oxide emissions from Vända free water surface constructed wetland, Tartu, Estonia
(Tartu Ülikool, 2021) Okiti, Isaac; Kasak, Kuno; Kill, Keit; 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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Nitrogen cycling genes abundance in soil and aboveground compartments of tropical peatland cloud forests and a wetland on Réunion Island
(2025) Kazmi, Fahad Ali; Espenberg, Mikk; Mander, Ülo; Ranniku, Reti; Öpik, Maarja; Püssa, Kersti; Soosaar, Kaido; Kasak, Kuno; Masta, Mohit; Ah-Peng, Claudine
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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Nitrous oxide as second most important greenhouse gas in tropical peatlands
(2024) Pärn, Jaan; Espenberg, Mikk; Soosaar, Kaido; Kasak, Kuno; Thayamkottu, Sandeep; Schindler, Thomas; Ranniku, Reti; Sohar, Kristina; Malaverri, Lizardo Fachín; Melling, Lulie; Mander, Ülo
Earth’s climate largely depends on carbon and nitrogen exchange between the atmosphere and tropical peatland ecosystems. Permanently wet peatlands take up carbon dioxide in plants and accumulate organic carbon in soil but release methane. Man-made drainage releases carbon dioxide from peat soils. Carbon and nitrous gas exchange and their relationships with tropical peatland conditions are poorly understood. We analysed natural peat swamp forests and fens, moderately drained and dry peatlands under a wide variety of land uses. The tropical peat swamp forests were large greenhouse gas sinks while tropical peatlands under moderate and low soil moisture levels emitted carbon dioxide and nitrous oxide. Carbon dioxide uptake of 160 mg m–2 h–1 dominated the net greenhouse gas budgets overall, while nitrous oxide emission of 90 mg CO2-equivalent m–2 h–1 on average was the second most important contributor (ahead of average methane emissions of 36 mg CO2-equivalent m–2 h–1) across the whole tropical peat moisture range.
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Põllumajanduslikku hajukoormust vähendava avaveelise tehismärgala metaani lendumine ja seda mõjutavad tegurid
(Tartu Ülikool, 2022) Teinlum, Mariel; Kasak, Kuno; Tartu Ülikool. Loodus- ja täppisteaduste valdkond
Metaan (CH4) ja süsinikdioksiid (CO2) on ühed levinumad kasvuhoonegaasid atmosfääris. Teadlased on aastakümneid uurinud võimalusi vee põllumajanduslikust äravoolust puhastamiseks ning üheks lahenduseks on rajatud märgalad, mis on keskkonnasõbralikud ja tõestatud toimima nii fosfori (P), lämmastiku (N) kui süsiniku (C) eemaldamisel (Kasak et al., 2018; Noorvee et al., 2007). Nimetatud toitainete eemaldamine võib omakorda vähendada keskkonnale kahjulikke CH4 ja CO2 emissioone (Nahlik ja Mitch, 2011). Käesolevas magistritöös uuritakse avaveelisi märgalasid. Uurimuseks koguti andmeid Lõuna-Eestis Uhti külas asuvast Vända tehismärgalast, mis koosneb kahest eraldi märgalast (2219m2 ja 2140m2). Andmeid koguti 2018. aasta aprillist kuni 2021. aasta augustini ujuvate kambrite meetodil 12-st erinevast mõõtepunktist. Gaasiproovid koguti eelevakueeritud 50ml klaaspudelitega kohe pärast kambri asetamist veepinnale, seejärel 20 minuti pärast, 40 minuti pärast ja 60 minuti pärast. Igast mõõtepunktist mõõdeti ka veeparameetreid. Käesoleva töö eesmärk on analüüsida metaani ja süsinikdioksiidi seoseid erinevate veeparameetrite vahel ning analüüsida metaani ja süsinikdioksiidi seoseid. Kuigi Spearmani korrelatsioon ei näidanud selgeid seoseid ühegi mõõdetud veeparameetri ja CH4, CO2 vahel, näitasid analüüsitud tulemused siiski selget seost mainitud kasvuhoonegaaside ja veesügavuse vahel. Näiteks registreeriti nimetatud kasvuhoonegaaside suurim heide suvel, kui temperatuur oli kõrgem ja veesügavus 20-30 cm või üle 30 cm.
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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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Soil moisture and microbiome explain greenhouse gas exchange in global peatlands
(2025) Pärn, Jaan; Espenberg, Mikk; Kasak, Kuno; Mander, Ülo; Thayamkottu, Sandeep; Öpik, Maarja; Bahram, Mohammad; Tedersoo, Leho; Davison, John Alexander; Maddison, Martin; Niinemets, Ülo; Ostonen, Ivika; Soosaar, Kaido; Sohar, Kristina; Zobel, Martin
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.