Sirvi Autor "Öpik, Maarja" järgi

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Arbuskulaarse mükoriisa roll taimede stressitaluvuses
(Tartu Ülikool, 2020) Sui, Simone; Öpik, Maarja; Sepp, Siim-Kaarel; Tartu Ülikool. Loodus- ja täppisteaduste valdkond; Tartu Ülikool. Botaanika osakond
Enamik maismaataimi on arbuskulaarmükoriissed. Arbuskulaarne mükoriisa on sümbioos taimejuure ja krohmseente (Glomeromycotina) vahel ning omab üliolulist rolli taimede toitainete kättesaadavuses ja omastamises. Lisaks on arbuskulaarsel mükoriisal teisigi tähtsaid funktsioone, näiteks taimede stressivastuste kujunemisel. Bakalaureusetöö eesmärk on anda ülevaade arbuskulaarse mükoriisa tähtsusest ökosüsteemides ja taimede biootilise ja abiootilise stressitaluvuses.
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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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Diversity of arbuscular mycorrhizal fungi in the roots of perennial plants and their effect on plant performance
(2004) Öpik, Maarja; Moora, Mari, juhendaja; Zobel, Martin, juhendaja
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Global peatland greenhouse gas dynamics: state of the art, processes, and perspectives
(New Phytologist, 2025) Mander, Ülo; Öpik, Maarja; Espenberg, Mikk
Natural peatlands regulate greenhouse gas (GHG) fluxes through a permanently high groundwater table, causing carbon dioxide (CO2) assimilation but methane (CH4) emissions due to anaerobic conditions. By contrast, drained and disturbed peatlands are hotspots for CO2 and nitrous oxide (N2O) emissions, while CH4 release is low but high from drainage ditches. Generally, in low-latitude (tropical and subtropical) peatlands, emissions of all GHGs are higher than in high-latitude (temperate, boreal, and Arctic) peatlands. Their inherent dependence on the water regime makes peatlands highly vulnerable to both direct and indirect anthropogenic impacts, including climate change-induced drying, which is creating anthro-natural ecosystems. This paper presents state-of-the-art knowledge on peatland GHG fluxes and their key regulating processes, highlighting approaches to study spatio-temporal dynamics, integrated methods, direct and indirect human impacts, and peatlands' perspectives.
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Global peatland greenhouse gas dynamics: state of the art, processes, and perspectives
(2025) Mander, Ülo; Espenberg, Mikk; Öpik, Maarja
Natural peatlands regulate greenhouse gas (GHG) fluxes through a permanently high groundwater table, causing carbon dioxide (CO2) assimilation but methane (CH4) emissions due to anaerobic conditions. By contrast, drained and disturbed peatlands are hotspots for CO2 and nitrous oxide (N2O) emissions, while CH4 release is low but high from drainage ditches. Generally, in low-latitude (tropical and subtropical) peatlands, emissions of all GHGs are higher than in high-latitude (temperate, boreal, and Arctic) peatlands. Their inherent dependence on the water regime makes peatlands highly vulnerable to both direct and indirect anthropogenic impacts, including climate change-induced drying, which is creating anthro-natural ecosystems. This paper presents state-of-the-art knowledge on peatland GHG fluxes and their key regulating processes, highlighting approaches to study spatio-temporal dynamics, integrated methods, direct and indirect human impacts, and peatlands' perspectives.
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Igavene tagasitulek: Kust me tuleme. Kes me oleme. Kuhu läheme
(2024) Summatavat, Kärt; Kikas, Jaak; Kuuse, Sulev; Mengel, Lilian; Aru, Krista; Nõmmik, Maarja; Einasto, Maret; Plats, Marja-Liisa; Öpik, Maarja
Sümpoosioni kava: 11.00 – Avasõnad - Krista Aru, Kärt Summatavet 11.15 Kust me tulime? - Richard Villems 11.45 Põhjala kaljujoonised – kalju(tänava)kunst või tee teadusesse – Sulev Kuuse 12.05 Kuidas maailm raamid sai? – Tõnu Viik 12.25 Seened on elu alus. Vaateid tagasi ja edasi – Maarja Öpik 12.45 Kõiksuse mustrid – Jaak Kikas 14.00 Me tuleme metsast, merest ja tuulest – Mare Kõiva 14.25 Siis ma sõlest sõna võti – Meelika Hainsoo 14.45 Kaljo Põllu. Rangelt vabatahtlik - Maarja Undusk 15.05 Lennart eesti rahva eesotsas – Toomas Kiho 15.25 Muusika ja abstraktne mõtlemine. Klaveripalad – Matti Reimann
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Maailma geomeetria – geomeetriline maailm
(2024-09-25) Summatavat, Kärt; Kikas, Jaak; Kuuse, Sulev; Mengel, Lilian; Nõmmik, Maarja; Einasto, Maret; Öpik, Maarja
11.00 Avasõnad 11.15 Laur Järv „Fundamentaalfüüsika geometriseerimine“ 11.45 Kärt Summatavet „Hingelkõnd geomeetrilisel alusmaastikul“ 12.15 Jaak Kikas „Kvaasikristallid“ 12.45 Elnara Taidre „Geomeetrilistest märkidest Tõnis Vindi kunstikontseptsioonis“ 13.15 - 14.15 Lõuna 14.15 Toivo Maimets „Turingi mustrid“ 14.45 Tiina Kraav „Origami geomeetria võludest“ 15.15 Arne Maasik „Geomeetria ja metafüüsika. Mare Vindist ja koostööst temaga“ 15.45 Kristel Mägedi „Mitmeilmne. Pilte ja viise“
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Maailma tähendusest
(2024-04-10) Summatavat, Kärt; Kikas, Jaak; Kuuse, Sulev; Mengel, Lilian; Aru, Krista; Nõmmik, Maarja; Einasto, Maret; Öpik, Maarja
11.00 „Tähenduste päritolu ja esteetika biosemiootiline alus“, Kalevi Kull, TÜ biosemiootika professor 11.55 "Kui korras peab olema keel? Tähendustest ja keelekriisist", Birute Lang-Klaas, TÜ eesti keele (võõrkeelena) professor 12.35 "Reeglite täitmise ilu - kord ja kaos klassikalises balletis", Triinu Upkin, Eesti Rahvusballeti baleriin 13.15 Kohvipaus 14.15 „Pärilikkuse aine“, Toivo Maimets, TÜ rakubioloogia professor 14.55 „Mu hundinahk või koeranahk - tont teab?”, Juhani Pütsepp, bioloog ja kirjanik 15.35 „Kvandilise maailma semiootikast“, Enn Kasak, teadusfilosoof ja astrofüüsik 16.15 „Kaootiline kord ja korralik kaos”, Helena Tulve, helilooja ja EMTA heliloomingu professor
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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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Puhaskultuuride tunnused liudikulaadsete seente (Pezizales) süstemaatikas
(Tartu Ülikool, 1998) Öpik, Maarja; Tartu Ülikool. Loodus- ja täppisteaduste valdkond; Tartu Ülikool. Botaanika osakond
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Role of soil properties and landscape composition in arbuscular mycorrhizal fungi communities of Estonia
(Tartu Ülikool, 2021) Zárate-Martínez, Oscar; Uuemaa, Evelyn; Öpik, Maarja; Tartu Ülikool. Geograafia osakond; Tartu Ülikool. Loodus- ja täppisteaduste valdkond
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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.
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Temporal and spatial dynamics of microbial communities and greenhouse gas flux responses to experimental flooding in riparian forest soils
(2025) Reiss, Kristel; Mander, Ülo; Öpik, Maarja; Sepp, Siim-Kaarel; Kanger, Kärt; Schindler, Thomas; Soosaar, Kaido; Pihlatie, Mari; Butterbach-Bahl, Klaus; Putkinen, Anuliina; Niinemets, Ülo; Espenberg, Mikk
Extreme rainfall and flooding are expected to increase in Northern subboreal habitats, altering soil hydrology and impacting greenhouse gas (GHG) fluxes by shifting redox potential and microbial communities as soils transition from aerobic to anaerobic conditions. This study examined the effects of a 2-week growing-season flash flood on bacterial, archaeal, and fungal communities and microbial processes driving CH4 and N2O fluxes in riparian alder (Alnus incana) forests. Flooding reduced soil nitrate accumulation as determined by quantitative polymerase chain reaction and promoted dinitrogen-fixing, nifH gene-carrying bacteria like Geomonas. Sequencing data showed that anaerobic bacteria (Oleiharenicola, Pelotalea) increased during the flood, while N2O emissions declined, indicating a shift towards complete denitrification to N2. However, drier patches within the flooded area emitted N2O, suggesting nitrification or incomplete denitrification. A diverse arbuscular mycorrhizal community was detected, including genera Acaulospora, Archaeospora, Claroideoglomus, Diversispora, and Paraglomus. Flooding increased the abundance of the fungal genera Naucoria, Russula, and Tomentella and the family Thelephoraceae, which symbiotically support alder trees in nitrogen uptake and carbon sequestration. Microtopographic differences of 0.3–0.7 m created spatial variability in GHG emissions during flooding, with some waterlogged areas emitting CH4, while others enhanced CH4 oxidation (determined by FAPROTAX) and promoted nitrification-driven N2O emissions in drier, elevated zones. We conclude that flash flooding during the active growing season significantly affects nitrogen-fixing and nitrifying microbes and alters symbiotic fungal community composition, creating spatial variability in GHG emissions.