Sirvi Autor "Kull, Ain" järgi

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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.
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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.
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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
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Eesti tuuleenergia atlase andmestiku moodustamine ja selle territoriaalse muutlikkuse analüüs
(Tartu Ülikool, 1995) Kull, Ain; Jaagus, Jaak, juhendaja
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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
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Impact of drainage on soil CH4 and N2O fluxes in nutrient-rich hemiboreal peatland forests of Europe
(2026) Kamil-Sardar, Muhammad; Laiho, Raija; Jauhiainen, Jyrki; Butlers, Aldis; Schindler, Thomas; Vahter, Hanna; Čiuldienė, Dovilė; Vigricas, Egidijus; Teemusk, Alar; Kull, Ain; Lazdiņš, Andis; Haberl, Andreas; Bārdule, Arta; Līcīte, Ieva; Samariks, Valters; Mander, Ülo; Armolaitis, Kęstutis; Soosaar, Kaido
Background and aims Peatland forests play a significant, yet highly variable, role in atmospheric methane (CH4) and nitrous oxide (N2O) emissions. Drainage reduces CH4 but increases N2O fluxes from nutrient-rich soils, creating complex climate trade-offs. To refine regional climate strategies, a clearer understanding of soil fluxes and influencing factors across forest types in the hemiboreal zone is needed. Methods This study presents two years of soil flux and environmental data collected from 2020 to 2023 using manual chambers at 18 drained (DF) and 7 undrained (UF) sites, with different tree species, in Estonia, Latvia, and Lithuania. Results Soil water‑table depth was the primary control on annual CH4 exchange; DF sites acted as CH4 sinks (–4.6 kg ha–1 y–1), whereas UF sites were net sources (38.2 kg ha–1 y–1). In contrast, N2O emissions occurred at all sites, averaging 5.9 kg ha–1 y–1 in DF and 1.4 kg ha–1 y–1 in UF soils. Within DF sites, Myrtillus‑type pine stands exhibited the lowest N2O fluxes, while alder stands showed the highest, followed by birch- and spruce-dominated stands, reflecting differences in hydrology, pH, and C/N ratios of the soil. Conclusions Our findings reveal significantly lower CH4 and moderately higher N2O emissions from DF soils than the IPCC Tier 1 temperate zone emission factor (EF), which has thus far been used for the hemiboreal zone. This study can improve national GHG inventories using specific information. We recommend applying Baltic region-specific EFs, as the mean annual CH4 and N2O emissions showed no significant difference across the three countries.
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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
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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
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National-scale geospatial modelling of recommended riparian buffer widths
(2026) Uuemaa, Evelyn; Kmoch, Alexander; Kull, Ain; Mõisja, Kiira; Tominga, Hanna-Ingrid; Guamán-Pintado, Pamela; Mander, Ülo
Determining optimal riparian buffer widths, especially considering landscape spatial heterogeneity, is challenging, often relying on computationally intensive hydrological models with limited scalability. Empirical nomographs, linking terrain, soil, and slope, offer a more tractable alternative. Building upon a nomograph developed for Estonian catchments in the earlier research, we present its first computational implementation within a geospatial modelling framework. We developed a geospatial modelling algorithm in Python to calculate recommended buffer widths based on slope, specific slope length (synthesised from flow length, slope length, and LS factor), and soil type, utilising high-resolution national datasets. This algorithm was applied to the entire territory of Estonia (approx. 43,000 km2). The model produces spatially explicit buffer width recommendations that reflect local variations in topography and soil conditions. The proposed framework provides a computationally efficient and scalable tool for supporting strategic planning, policy development, and prioritisation of riparian buffer implementation. While not intended for direct site-level design, it offers a robust first-order assessment of spatial patterns in buffer width requirements and can be further refined through local calibration and validation.
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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.
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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.
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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
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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
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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