Sirvi Autor "Kull, Ain" järgi

Nüüd näidatakse 1 - 12 12

listelement.badge.access-status Avatud juurdepääs ,
A comprehensive porewater survey of European peatlands reveals sustained elevated phosphorus levels after 10–20 years of rewetting
(2025) Krishnankutty, Nimisha; Gelbrecht, Jörg; Petersen, Rasmus Jes; Rayner, Dylan; Lau, Maximilian P.; Frank, Stefan; Andersen, Roxane; Pärn, Jaan; Mander, Ülo; Hoffmann, Carl C.; Mäenpää, Maarit I.; Goldhammer, Tobias; Kull, Ain; Florea, Adrian-Florin; Zak, Dominik
Rewetting drained peatlands can lead to high nutrient mobilization, increased methane emissions, and a slow re-establishment of peat-forming vegetation. To guide effective restoration and management, understanding the temporal and spatial variability in porewater chemistry is essential. This study surveyed 64 natural and rewetted peatlands across Germany, Poland, Estonia, Sweden, Georgia, and Scotland from 1997 to 2017. A total of 812 anoxic porewater samples were collected using dialysis samplers (0–0.6 m depth). The rewetted fens exhibited a wide range of dissolved substances, spanning orders of magnitude for soluble reactive phosphorus (SRP: 0.1–18.9 mg L−1), ammonium (NH4+-N: 0.1–117.3 mg L−1), and dissolved organic carbon (DOC: 13–313 mg L−1). However, the mean concentrations were significantly higher than those observed in natural fens (p < 0.05). Depth-integrated mobilization rates for nutrients in rewetted fens were, on average, 23 times higher for SRP (1.8 mg P m−2 d-1) and 4.6 times higher for NH4+-N (3.6 mg N m−2 d-1) compared to their natural counterparts (0.1 mg P m−2 d-1 and 0.8 mg N m−2 d-1). Seasonal variation was also evident in rewetted fens densely colonized by helophytes, with SRP concentrations being lower in the growing season. Notably, SRP concentrations remained elevated 10–20 years after rewetting; however, a 50–80 % decrease was observed at sites characterized by comparatively low iron content in the peat (< 20 mg g−1 dry mass). Further investigations should explore how nutrient dynamics evolve over extended rewetting periods in different contexts, including climate change.
listelement.badge.access-status Avatud juurdepääs ,
A comprehensive porewater survey of European peatlands reveals sustained elevated phosphorus levels after 10–20 years of rewetting
(2025) Krishnankutty,; Gelbrecht, Jörg; Petersen, Rasmus Jes; Rayner, Dylan; Lau, Maximilian P.; Frank, Stefan; Andersen, Roxane; Pärn, Jaan; Mander, Ülo; Kotowski, Wiktor; Liu, Haojie; Iversen, Bo V.; Heckrath, Goswin; Hansen, Hans C.B.; Hoffmann, Carl C.; Mäenpää, Maarit I.; Goldhammer, Tobias; Kull, Ain; Florea, Adrian-Florin; Zak, Dominik
Rewetting drained peatlands can lead to high nutrient mobilization, increased methane emissions, and a slow re-establishment of peat-forming vegetation. To guide effective restoration and management, understanding the temporal and spatial variability in porewater chemistry is essential. This study surveyed 64 natural and rewetted peatlands across Germany, Poland, Estonia, Sweden, Georgia, and Scotland from 1997 to 2017. A total of 812 anoxic porewater samples were collected using dialysis samplers (0–0.6 m depth). The rewetted fens exhibited a wide range of dissolved substances, spanning orders of magnitude for soluble reactive phosphorus (SRP: 0.1–18.9 mg L−1), ammonium (NH4+-N: 0.1–117.3 mg L−1), and dissolved organic carbon (DOC: 13–313 mg L−1). However, the mean concentrations were significantly higher than those observed in natural fens (p < 0.05). Depth-integrated mobilization rates for nutrients in rewetted fens were, on average, 23 times higher for SRP (1.8 mg P m−2 d-1) and 4.6 times higher for NH4+-N (3.6 mg N m−2 d-1) compared to their natural counterparts (0.1 mg P m−2 d-1 and 0.8 mg N m−2 d-1). Seasonal variation was also evident in rewetted fens densely colonized by helophytes, with SRP concentrations being lower in the growing season. Notably, SRP concentrations remained elevated 10–20 years after rewetting; however, a 50–80 % decrease was observed at sites characterized by comparatively low iron content in the peat (< 20 mg g−1 dry mass). Further investigations should explore how nutrient dynamics evolve over extended rewetting periods in different contexts, including climate change.
listelement.badge.access-status Avatud juurdepääs ,
A GIS-based multi-criteria evaluation of the wind energy potential of Kherson and Zaporizhzhia oblasts of Ukraine
(Tartu Ülikool, 2020) Dmytrenko, Denys; Kull, Ain; Tartu Ülikool. Geograafia osakond; Tartu Ülikool. Loodus- ja täppisteaduste valdkond
listelement.badge.access-status Embargo ,
Eesti tuuleenergia atlase andmestiku moodustamine ja selle territoriaalse muutlikkuse analüüs
(Tartu Ülikool, 1995) Kull, Ain; Jaagus, Jaak, juhendaja
listelement.badge.access-status Avatud juurdepääs ,
EstSoil-EH: a high-resolution eco-hydrological modelling parameters dataset for Estonia
(Earth System Science Data, 2021-01-21) Kmoch, Alexander; Kanal, Arno; Astover, Alar; Kull, Ain; Virro, Holger; Helm, Aveliina; Pärtel, Meelis; Ostonen, Ivika; Uuemaa, Evelyn
listelement.badge.access-status Avatud juurdepääs ,
Jääksoode korrastamine ja märgalaviljelus ning selle mõju kasvuhoonegaaside voole
(Tartu Ülikool, 2023) Kass, Ülle; Kull, Ain; Tartu Ülikool. Geograafia osakond; Tartu Ülikool. Loodus- ja täppisteaduste valdkond
listelement.badge.access-status Avatud juurdepääs ,
Jääksoodes toimuvate muutuste analüüsimine LiDAR andmetel
(Tartu Ülikool, 2019) Toomsalu, Ott; Kull, Ain; Aunap, Raivo; Tartu Ülikool. Geograafia osakond; Tartu Ülikool. Loodus- ja täppisteaduste valdkond
listelement.badge.access-status Avatud juurdepääs ,
Peatland restoration pathways to mitigate greenhouse gas emissions and retain peat carbon
(2023) Mander, Ülo; Espenberg, Mikk; Melling, Lulie; Kull, Ain
Peatlands play a crucial role in the global carbon (C) cycle, making their restoration a key strategy for mitigating greenhouse gas (GHG) emissions and retaining C. This study analyses the most common restoration pathways employed in boreal and temperate peatlands, potentially applicable in tropical peat swamp forests. Our analysis focuses on the GHG emissions and C retention potential of the restoration measures. To assess the C stock change in restored (rewetted) peatlands and afforested peatlands with continuous drainage, we adopt a conceptual approach that considers short-term C capture (GHG exchange between the atmosphere and the peatland ecosystem) and long-term C sequestration in peat. The primary criterion of our conceptual model is the capacity of restoration measures to capture C and reduce GHG emissions. Our findings indicate that carbon dioxide (CO2) is the most influential part of long-term climate impact of restored peatlands, whereas moderate methane (CH4) emissions and low N2O fluxes are relatively unimportant. However, lateral losses of dissolved and particulate C in water can account up to a half of the total C stock change. Among the restored peatland types, Sphagnum paludiculture showed the highest CO2 capture, followed by shallow lakes and reed/grass paludiculture. Shallow lakeshore vegetation in restored peatlands can reduce CO2 emissions and sequester C but still emit CH4, particularly during the first 20 years after restoration. Our conceptual modelling approach reveals that over a 300-year period, under stable climate conditions, drained bog forests can lose up to 50% of initial C content. In managed (regularly harvested) and continuously drained peatland forests, C accumulation in biomass and litter input does not compensate C losses from peat. In contrast, rewetted unmanaged peatland forests are turning into a persistent C sink. The modelling results emphasized the importance of long-term C balance analysis which considers soil C accumulation, moving beyond the short-term C cycling between vegetation and the atmosphere.
listelement.badge.access-status Avatud juurdepääs ,
Peatland restoration pathways to mitigate greenhouse gas emissions and retain peat carbon
(2024) Mander, Ülo; Espenberg, Mikk; Melling, Lulie; Kull, Ain
Peatlands play a crucial role in the global carbon (C) cycle, making their restoration a key strategy for mitigating greenhouse gas (GHG) emissions and retaining C. This study analyses the most common restoration pathways employed in boreal and temperate peatlands, potentially applicable in tropical peat swamp forests. Our analysis focuses on the GHG emissions and C retention potential of the restoration measures. To assess the C stock change in restored (rewetted) peatlands and afforested peatlands with continuous drainage, we adopt a conceptual approach that considers short-term C capture (GHG exchange between the atmosphere and the peatland ecosystem) and long-term C sequestration in peat. The primary criterion of our conceptual model is the capacity of restoration measures to capture C and reduce GHG emissions. Our findings indicate that carbon dioxide (CO2) is the most influential part of long-term climate impact of restored peatlands, whereas moderate methane (CH4) emissions and low N2O fluxes are relatively unimportant. However, lateral losses of dissolved and particulate C in water can account up to a half of the total C stock change. Among the restored peatland types, Sphagnum paludiculture showed the highest CO2 capture, followed by shallow lakes and reed/grass paludiculture. Shallow lakeshore vegetation in restored peatlands can reduce CO2 emissions and sequester C but still emit CH4, particularly during the first 20 years after restoration. Our conceptual modelling approach reveals that over a 300-year period, under stable climate conditions, drained bog forests can lose up to 50% of initial C content. In managed (regularly harvested) and continuously drained peatland forests, C accumulation in biomass and litter input does not compensate C losses from peat. In contrast, rewetted unmanaged peatland forests are turning into a persistent C sink. The modelling results emphasized the importance of long-term C balance analysis which considers soil C accumulation, moving beyond the short-term C cycling between vegetation and the atmosphere.
listelement.badge.access-status Avatud juurdepääs ,
Reljeefiomaduste ja põllukultuuride saagikuse vahelised seosed kasutades täppispõllunduse andmeid
(Tartu Ülikool, 2018) Hark, Anu; Kull, Ain; Tartu Ülikool. Geograafia osakond; Tartu Ülikool. Loodus- ja täppisteaduste valdkond
listelement.badge.access-status Avatud juurdepääs ,
Tuuleenergeetika kajastamise erinevustest ajalehtedes Hiiumaa ja kogu Eesti näitel
(Tartu Ülikool, 2017) Ütt, Mari-Ann; Kull, Ain; Tartu Ülikool. Geograafia osakond; Tartu Ülikool. Loodus- ja täppisteaduste valdkond
listelement.badge.access-status Avatud juurdepääs ,
Veerežiimi häiringute ja ilmastiku mõju hariliku männi (Pinus sylvestris L.) radiaalsele juurdekasvule Lehtmetsa soo näitel
(Tartu Ülikool, 2022) Erikson, Kärt; Läänelaid, Alar; Kull, Ain; Sohar, Kristina; Tartu Ülikool. Geograafia osakond; Tartu Ülikool. Loodus- ja täppisteaduste valdkond