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Riparian forests are known as hot spots of nitrogen cycling in landscapes. Climate warming speeds up the cycle. Here we present results from a multi-annual high temporal-frequency study of soil, stem, and ecosystem (eddy covariance) fluxes of N2O from a typical riparian forest in Europe. Hot moments (extreme events of N2O emission) lasted a quarter of the study period but contributed more than half of soil fluxes. We demonstrate that high soil emissions of N2O do not escape the ecosystem but are processed in the canopy. Rapid water content change across intermediate soil moisture was a major determinant of elevated soil emissions in spring. The freeze-thaw period is another hot moment. However, according to the eddy covariance measurements, the riparian forest is a modest source of N2O. We propose photochemical reactions and dissolution in canopy-space water as reduction mechanisms.
Ülo Mander; Alisa Krasnova; Jordi Escuer-Gatius; Mikk Espenberg; Thomas Schindler; Katerina Machacova; Jaan Pärn; Martin Maddison; J. Patrick Megonigal; Mari Pihlatie; Kuno Kasak; Ülo Niinemets; Heikki Junninen; Kaido Soosaar. Forest canopy mitigates soil N2O emission during hot moments. npj Climate and Atmospheric Science 2021, 4, 1 -9.
AMA StyleÜlo Mander, Alisa Krasnova, Jordi Escuer-Gatius, Mikk Espenberg, Thomas Schindler, Katerina Machacova, Jaan Pärn, Martin Maddison, J. Patrick Megonigal, Mari Pihlatie, Kuno Kasak, Ülo Niinemets, Heikki Junninen, Kaido Soosaar. Forest canopy mitigates soil N2O emission during hot moments. npj Climate and Atmospheric Science. 2021; 4 (1):1-9.
Chicago/Turabian StyleÜlo Mander; Alisa Krasnova; Jordi Escuer-Gatius; Mikk Espenberg; Thomas Schindler; Katerina Machacova; Jaan Pärn; Martin Maddison; J. Patrick Megonigal; Mari Pihlatie; Kuno Kasak; Ülo Niinemets; Heikki Junninen; Kaido Soosaar. 2021. "Forest canopy mitigates soil N2O emission during hot moments." npj Climate and Atmospheric Science 4, no. 1: 1-9.
Tree stems play an important role in forest methane (CH4) and nitrous oxide (N2O) flux dynamics. Our paper aimed to determine the unknown diurnal variability of CH4 and N2O exchange in grey alder tree stems. The gas fluxes in tree stems and adjacent soil were measured using manual static and dynamic chamber systems with gas chromatographic and laser-spectroscopic analysis, respectively. The alder trees were predominant emitters of CH4 and N2O; however, N2O emission from stems was negligible. The soil mainly emitted N2O into the atmosphere and was both a source and sink of CH4, depending on environmental conditions. Neither the tree stems nor the riparian forest soil showed significant differences in their CH4 and N2O fluxes between the daytime and nighttime, independently of the exchange rates. In contrast to several previous studies revealing a diurnal variability of greenhouse gas fluxes from tree stems, our investigation did not show any clear daytime–nighttime differences. On the other hand, we found quite clear seasonal dynamics initiated by changing environmental conditions, such as temperature and soil water conditions and tree physiological activity. Our results imply a transport role of tree stems for soil-produced CH4 and N2O rather than the production of these gases in tree tissues, even though this cannot be excluded.
Thomas Schindler; Katerina Machacova; Ülo Mander; Jordi Escuer-Gatius; Kaido Soosaar. Diurnal Tree Stem CH4 and N2O Flux Dynamics from a Riparian Alder Forest. Forests 2021, 12, 863 .
AMA StyleThomas Schindler, Katerina Machacova, Ülo Mander, Jordi Escuer-Gatius, Kaido Soosaar. Diurnal Tree Stem CH4 and N2O Flux Dynamics from a Riparian Alder Forest. Forests. 2021; 12 (7):863.
Chicago/Turabian StyleThomas Schindler; Katerina Machacova; Ülo Mander; Jordi Escuer-Gatius; Kaido Soosaar. 2021. "Diurnal Tree Stem CH4 and N2O Flux Dynamics from a Riparian Alder Forest." Forests 12, no. 7: 863.
Katerina Machacova; Thomas Schindler; Kaido Soosaar. Fourier transform infrared spectroscopy and interference of volatile organic compounds on measurements of methane (CH 4 ) fluxes at tree stems – a general phenomenon for plant systems? New Phytologist 2021, 230, 2100 -2104.
AMA StyleKaterina Machacova, Thomas Schindler, Kaido Soosaar. Fourier transform infrared spectroscopy and interference of volatile organic compounds on measurements of methane (CH 4 ) fluxes at tree stems – a general phenomenon for plant systems? New Phytologist. 2021; 230 (6):2100-2104.
Chicago/Turabian StyleKaterina Machacova; Thomas Schindler; Kaido Soosaar. 2021. "Fourier transform infrared spectroscopy and interference of volatile organic compounds on measurements of methane (CH 4 ) fluxes at tree stems – a general phenomenon for plant systems?" New Phytologist 230, no. 6: 2100-2104.
Trees are known to emit methane (CH4) and nitrous oxide (N2O), with tropical wetland trees being considerable CH4 sources. Little is known about CH4 and especially N2O exchange of trees growing in tropical rain forests under nonflooded conditions.We determined CH4 and N2O exchange of stems of six dominant tree species, cryptogamic stem covers, soils and volcanic surfaces at the start of the rainy season in a 400‐yr‐old tropical lowland rain forest situated on a basaltic lava flow (Réunion Island). We aimed to understand the unknown role in greenhouse gas fluxes of these atypical tropical rain forests on basaltic lava flows.The stems studied were net sinks for atmospheric CH4 and N2O, as were cryptogams, which seemed to be co‐responsible for the stem uptake. In contrast with more commonly studied rain forests, the soil and previously unexplored volcanic surfaces consumed CH4. Their N2O fluxes were negligible.Greenhouse gas uptake potential by trees and cryptogams constitutes a novel and unique finding, thus showing that plants can serve not only as emitters, but also as consumers of CH4 and N2O. The volcanic tropical lowland rain forest appears to be an important CH4 sink, as well as a possible N2O sink.
Katerina Machacova; Libor Borak; Thomas Agyei; Thomas Schindler; Kaido Soosaar; Ülo Mander; Claudine Ah‐Peng. Trees as net sinks for methane (CH 4 ) and nitrous oxide (N 2 O) in the lowland tropical rain forest on volcanic Réunion Island. New Phytologist 2020, 229, 1983 -1994.
AMA StyleKaterina Machacova, Libor Borak, Thomas Agyei, Thomas Schindler, Kaido Soosaar, Ülo Mander, Claudine Ah‐Peng. Trees as net sinks for methane (CH 4 ) and nitrous oxide (N 2 O) in the lowland tropical rain forest on volcanic Réunion Island. New Phytologist. 2020; 229 (4):1983-1994.
Chicago/Turabian StyleKaterina Machacova; Libor Borak; Thomas Agyei; Thomas Schindler; Kaido Soosaar; Ülo Mander; Claudine Ah‐Peng. 2020. "Trees as net sinks for methane (CH 4 ) and nitrous oxide (N 2 O) in the lowland tropical rain forest on volcanic Réunion Island." New Phytologist 229, no. 4: 1983-1994.
The decomposition of fresh crop residues added to soil for agricultural purposes is complex. This is due to different factors that influence the decomposition process. In field conditions, the incorporation of crop residues into soil does not always have a positive effect on aggregate stability. The aim of this study was to investigate the decomposition effects of residues from two different cover crops (Brassica napus var. oleifera and Secale cereale) and one main crop (wheat straw) on soil aggregate stability. A 105-day incubation experiment was conducted in which crop residues were mixed with sandy loam soil at a rate of 6 g C kg−1 of soil. During the incubation, there were five water additions. The decomposition effects of organic matter on soil conditions during incubation were evaluated by determining the soil functional groups; carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) emissions; soil microbial biomass carbon (MBC); and water-stable aggregates (WSA). The functional groups of the plant residues and the soil were analyzed using Fourier transform infrared spectroscopy (FTIR) and a double exponential model was used to estimate the decomposition rates. The results show that the decomposition rate of fresh organic materials was correlated with the soil functional groups and the C/N ratio. Oilseed rape and rye, with lower C/N ratios than wheat straw residues, had faster decomposition rates and higher CO2 and N2O emissions than wheat straw. The CO2 and N2O flush at the start of the experiment corresponded to a decrease of soil aggregate stability (from Day 3 to Day 10 for CO2 and from Day 19 to Day 28 for N2O emissions), which was linked to higher decomposition rates of the labile fraction. The lower decomposition rates contributed to higher remaining C (carbon) and higher soil aggregate stability. The results also show that changes in the soil functional groups due to crop residue incorporation did not significantly influence aggregate stability. Soil moisture (SM) negatively influenced the aggregate stability and greenhouse gas emissions (GHG) in all treatments (oilseed rape, rye, wheat straw, and control). Irrespective of the water addition procedure, rye and wheat straw residues had a positive effect on water-stable aggregates more frequently than oilseed rape during the incubation period. The results presented here may contribute to a better understanding of decomposition processes after the incorporation of fresh crop residues from cover crops. A future field study investigating the influence of incorporation rates of different crop residues on soil aggregate stability would be of great interest.
Gheorghe Stegarescu; Jordi Escuer-Gatius; Kaido Soosaar; Karin Kauer; Tõnu Tõnutare; Alar Astover; Endla Reintam. Effect of Crop Residue Decomposition on Soil Aggregate Stability. Agriculture 2020, 10, 527 .
AMA StyleGheorghe Stegarescu, Jordi Escuer-Gatius, Kaido Soosaar, Karin Kauer, Tõnu Tõnutare, Alar Astover, Endla Reintam. Effect of Crop Residue Decomposition on Soil Aggregate Stability. Agriculture. 2020; 10 (11):527.
Chicago/Turabian StyleGheorghe Stegarescu; Jordi Escuer-Gatius; Kaido Soosaar; Karin Kauer; Tõnu Tõnutare; Alar Astover; Endla Reintam. 2020. "Effect of Crop Residue Decomposition on Soil Aggregate Stability." Agriculture 10, no. 11: 527.
Nitrification inhibitors have been proposed as a tool to mitigate nitrous oxide (N2O) emissions from agriculture, which are caused mainly by fertilization. The nitrification inhibitor 3,4-Dimethylpyrazole phosphate (DMPP) was tested in a winter rapeseed field after dairy slurry application in Central Estonia. N2O emissions were monitored using the closed chamber method. Soil and leachate chemical parameters were also analyzed. N2O emissions increased from pre-slurry application values of 316 and 264 µg m−2 h−1 for the control and treatment plot, respectively, to maximum values of 3130.71 and 4834 µg m−2 h−1, with cumulative emissions during the study period of 12.30 kg ha−1 for the control plot and 17.70 kg ha−1 for the treatment plot. The intense precipitation period that began with the application of the slurry resulted in changes in soil moisture and water-filled pore space (WFPS), modifying the nitrification/denitrification balance. Positive significant correlations (p = 0.016 and p = 0.037, for the control and treatment plot, respectively) were found between N2O fluxes and WFPS. Future studies should consider the role of nitrifier and denitrifier communities in order to better assess in-field nitrification inhibitor effectiveness.
Jordi Escuer-Gatius; Merrit Shanskiy; Ülo Mander; Karin Kauer; Alar Astover; Hanna Vahter; Kaido Soosaar. Intensive Rain Hampers the Effectiveness of Nitrification Inhibition in Controlling N2O Emissions from Dairy Slurry-Fertilized Soils. Agriculture 2020, 10, 497 .
AMA StyleJordi Escuer-Gatius, Merrit Shanskiy, Ülo Mander, Karin Kauer, Alar Astover, Hanna Vahter, Kaido Soosaar. Intensive Rain Hampers the Effectiveness of Nitrification Inhibition in Controlling N2O Emissions from Dairy Slurry-Fertilized Soils. Agriculture. 2020; 10 (11):497.
Chicago/Turabian StyleJordi Escuer-Gatius; Merrit Shanskiy; Ülo Mander; Karin Kauer; Alar Astover; Hanna Vahter; Kaido Soosaar. 2020. "Intensive Rain Hampers the Effectiveness of Nitrification Inhibition in Controlling N2O Emissions from Dairy Slurry-Fertilized Soils." Agriculture 10, no. 11: 497.
Biochar has been proposed as an amendment that can improve soil conditions, increase harvest yield, and reduce N losses through NO3− leaching and N2O emissions. We conducted an experiment to test the hay biochar mitigation effect on N2O emissions depending on its production temperature. The pot experiment consisted of the soil amendment with three different production temperature biochars (300 °C, 550 °C, 850 °C) alone and in combination with three different organic fertilizers (cattle slurry, slurry digestate, vinasse), in growth chamber conditions. The effects of biochar and fertilizer were both significant, but the interaction biochar:fertilizer was not. The amendment with the three fertilizer types and with the highest production temperature biochar resulted in significantly higher cumulative N2O fluxes. Biochar did not show a mitigation effect on N2O emissions when applied with organic fertilizer. Cumulative emissions were higher with biochar addition, with increasing emissions for increasing biochar production temperature. Our results support the idea that biochar cannot be considered as a universal tool for the reduction of N2O emissions.
Jordi Escuer-Gatius; Merrit Shanskiy; Kaido Soosaar; Alar Astover; Henn Raave. High-Temperature Hay Biochar Application into Soil Increases N2O Fluxes. Agronomy 2020, 10, 109 .
AMA StyleJordi Escuer-Gatius, Merrit Shanskiy, Kaido Soosaar, Alar Astover, Henn Raave. High-Temperature Hay Biochar Application into Soil Increases N2O Fluxes. Agronomy. 2020; 10 (1):109.
Chicago/Turabian StyleJordi Escuer-Gatius; Merrit Shanskiy; Kaido Soosaar; Alar Astover; Henn Raave. 2020. "High-Temperature Hay Biochar Application into Soil Increases N2O Fluxes." Agronomy 10, no. 1: 109.
Hemiboreal forests form a transitional belt between boreal and temperate forests in Eurasia, and due to long-term climate warming they could potentially expand in a northerly direction. However, carbon (C) exchange studies in this transitional forest type are scarce. In 2014–2015 we analyzed CO2 exchange in a hemiboreal mixed forest at SMEAR Estonia (Station for Measuring Ecosystem-Atmosphere Relations) using eddy covariance (EC), soil chamber technique and biometric methods. Employing two plots that differ in forest stand composition (mixed (MP) and coniferous (CP)) located within the footprint of the EC tower, we evaluated heterotrophic and total soil respiration (Rh and Rs, respectively). Measurements showed that C, nitrogen (N), and soil organic matter (SOM) contents in topsoil were significantly higher in the coniferous plot, and the total C stock until 20 cm of mineral soil was higher by a factor of two (i.e., 170.6 and 94.8 t C ha−1 for the CP and MP, respectively). Only in 2015 there was a significant difference in Rs between the plots, while Rh exhibited no detectable difference. The cumulative Rs during the growing season was similar for both plots (CP and MP) and years: 532 and 548 g m−2, respectively, in 2014; 636 and 592 g m−2, respectively, in 2015. The same applied to Rh: 418 and 430 g m−2, respectively, in 2014; 406 and 387 g m−2, respectively, in 2015. The forest as a whole was a C sink. In 2015, net ecosystem exchange (NEE) was -585.62 ± 45.16 g C m−2 yr−1 (the average and SD of two gap-filling methods: MDS and nonlinear regressions). Gross primary production (GPP), and ecosystem respiration (RE) were -1280.62 ± 53.36, and 696.00 ± 98.51 g C m−2 yr−1, respectively (the average and SD of two flux partitioning methods: nighttime data-based and daytime data-based). NEE and GPP suggested a greater similarity to temperate forests, while RE was closer to more boreal forest stands. The mean value of net ecosystem production (NEP) of both plots, estimated using forest stand biometric, litter and chamber data was similar to the annual NEE value: 6.3 and −5.9 t C ha−1 yr−1, respectively.
Alisa Krasnova; Mai Kukumägi; Ülo Mander; Raili Torga; Dmitrii Krasnov; Steffen M. Noe; Ivika Ostonen; Ülle Püttsepp; Helen Killian; Veiko Uri; Krista Lõhmus; Jaak Sõber; Kaido Soosaar. Carbon exchange in a hemiboreal mixed forest in relation to tree species composition. Agricultural and Forest Meteorology 2019, 275, 11 -23.
AMA StyleAlisa Krasnova, Mai Kukumägi, Ülo Mander, Raili Torga, Dmitrii Krasnov, Steffen M. Noe, Ivika Ostonen, Ülle Püttsepp, Helen Killian, Veiko Uri, Krista Lõhmus, Jaak Sõber, Kaido Soosaar. Carbon exchange in a hemiboreal mixed forest in relation to tree species composition. Agricultural and Forest Meteorology. 2019; 275 ():11-23.
Chicago/Turabian StyleAlisa Krasnova; Mai Kukumägi; Ülo Mander; Raili Torga; Dmitrii Krasnov; Steffen M. Noe; Ivika Ostonen; Ülle Püttsepp; Helen Killian; Veiko Uri; Krista Lõhmus; Jaak Sõber; Kaido Soosaar. 2019. "Carbon exchange in a hemiboreal mixed forest in relation to tree species composition." Agricultural and Forest Meteorology 275, no. : 11-23.
Clear-cutting is a conventional method of forest management which significantly changes carbon (C) cycling at the ecosystem level for a long time. Estimation of the interim period during which the ecosystem turns from a C source to a C sink is crucial for clarifying the environmental effects of management on forest C cycling. The current study provided new knowledge of C cycling in young pine stand and demonstrated the recovery of C sequestration of the forest ecosystem during the post harvesting period. We estimated the C balance in a 6-year-old Scots pine stand by using two different methods: carbon budgeting, for estimating annual net ecosystem production (NEP), and eddy covariance (EC), for estimating net ecosystem exchange (NEE). For C budgeting, the above- and belowground biomass production of the ecosystem, as well as the soil heterotrophic respiration efflux at the studied site was estimated. Annual NEE at the studied young forest ecosystem was 1.19 ± 0.36 t C ha−1, gross primary ecosystem production was 9.87 and total ecosystem respiration was 11.06 t C ha−1. Estimated NEE was in good accordance with the results of NEP (1.37 t C ha−1), which confirms the relevance of the C budgeting method. Increased annual woody biomass production is the main factor which induced the young Scots pine ecosystem to act as a C sink: annual C accumulation in tree biomass in a 6-year-old stand was 1.0 t C ha−1 but reached already 2.4 t C ha−1 in the following year. Assuming that the annual Rh flux is of the same magnitude in the subsequent years, the ecosystem will become a C sink already during a short period after clear-cut. Annual soil respiration (Rs) and heterotrophic soil respiration (Rh) were 6.0 and 4.2 t C ha−1, respectively and the Rh/Rs ratio was 0.70. However, at this stage also the understorey vegetation contributed essentially to NEP, making up 56% of the annual C uptake accumulated in the plants. The methane flux and the leached C flux were negligible, 0.004 and 0.015 t C ha−1 yr−1, respectively. Our results demonstrate that well regenerated young Scots pine stand on a former clear-cut area will be able to turn into a C sequestering ecosystem already before ten years after cutting.
Veiko Uri; Mai Kukumägi; Jürgen Aosaar; Mats Varik; Hardo Becker; Kristiina Aun; Alisa Krasnova; Gunnar Morozov; Ivika Ostonen; Ülo Mander; Krista Lõhmus; Katrin Rosenvald; Kaie Kriiska; Kaido Soosaar. The carbon balance of a six-year-old Scots pine (Pinus sylvestris L.) ecosystem estimated by different methods. Forest Ecology and Management 2018, 433, 248 -262.
AMA StyleVeiko Uri, Mai Kukumägi, Jürgen Aosaar, Mats Varik, Hardo Becker, Kristiina Aun, Alisa Krasnova, Gunnar Morozov, Ivika Ostonen, Ülo Mander, Krista Lõhmus, Katrin Rosenvald, Kaie Kriiska, Kaido Soosaar. The carbon balance of a six-year-old Scots pine (Pinus sylvestris L.) ecosystem estimated by different methods. Forest Ecology and Management. 2018; 433 ():248-262.
Chicago/Turabian StyleVeiko Uri; Mai Kukumägi; Jürgen Aosaar; Mats Varik; Hardo Becker; Kristiina Aun; Alisa Krasnova; Gunnar Morozov; Ivika Ostonen; Ülo Mander; Krista Lõhmus; Katrin Rosenvald; Kaie Kriiska; Kaido Soosaar. 2018. "The carbon balance of a six-year-old Scots pine (Pinus sylvestris L.) ecosystem estimated by different methods." Forest Ecology and Management 433, no. : 248-262.
Nitrous oxide (N2O) is a powerful greenhouse gas and the main driver of stratospheric ozone depletion. Since soils are the largest source of N2O, predicting soil response to changes in climate or land use is central to understanding and managing N2O. Here we find that N2O flux can be predicted by models incorporating soil nitrate concentration (NO3−), water content and temperature using a global field survey of N2O emissions and potential driving factors across a wide range of organic soils. N2O emissions increase with NO3− and follow a bell-shaped distribution with water content. Combining the two functions explains 72% of N2O emission from all organic soils. Above 5 mg NO3−-N kg−1, either draining wet soils or irrigating well-drained soils increases N2O emission by orders of magnitude. As soil temperature together with NO3− explains 69% of N2O emission, tropical wetlands should be a priority for N2O management.
Jaan Pärn; Jos T. A. Verhoeven; Klaus Butterbach-Bahl; Nancy B. Dise; Sami Ullah; Anto Aasa; Sergey Egorov; Mikk Espenberg; Järvi Järveoja; Jyrki Jauhiainen; Kuno Kasak; Leif Klemedtsson; Ain Kull; Fatima Laggoun-Défarge; Elena Lapshina; Annalea Lohila; Krista Lõhmus; Martin Maddison; William J. Mitsch; Christoph Müller; Ülo Niinemets; Bruce Osborne; Taavi Pae; Jüri-Ott Salm; Fotis Sgouridis; Kristina Sohar; Kaido Soosaar; Kathryn Storey; Alar Teemusk; Moses M. Tenywa; Julien Tournebize; Jaak Truu; Gert Veber; Jorge A. Villa; Seint Sann Zaw; Ülo Mander. Nitrogen-rich organic soils under warm well-drained conditions are global nitrous oxide emission hotspots. Nature Communications 2018, 9, 1135 .
AMA StyleJaan Pärn, Jos T. A. Verhoeven, Klaus Butterbach-Bahl, Nancy B. Dise, Sami Ullah, Anto Aasa, Sergey Egorov, Mikk Espenberg, Järvi Järveoja, Jyrki Jauhiainen, Kuno Kasak, Leif Klemedtsson, Ain Kull, Fatima Laggoun-Défarge, Elena Lapshina, Annalea Lohila, Krista Lõhmus, Martin Maddison, William J. Mitsch, Christoph Müller, Ülo Niinemets, Bruce Osborne, Taavi Pae, Jüri-Ott Salm, Fotis Sgouridis, Kristina Sohar, Kaido Soosaar, Kathryn Storey, Alar Teemusk, Moses M. Tenywa, Julien Tournebize, Jaak Truu, Gert Veber, Jorge A. Villa, Seint Sann Zaw, Ülo Mander. Nitrogen-rich organic soils under warm well-drained conditions are global nitrous oxide emission hotspots. Nature Communications. 2018; 9 (1):1135.
Chicago/Turabian StyleJaan Pärn; Jos T. A. Verhoeven; Klaus Butterbach-Bahl; Nancy B. Dise; Sami Ullah; Anto Aasa; Sergey Egorov; Mikk Espenberg; Järvi Järveoja; Jyrki Jauhiainen; Kuno Kasak; Leif Klemedtsson; Ain Kull; Fatima Laggoun-Défarge; Elena Lapshina; Annalea Lohila; Krista Lõhmus; Martin Maddison; William J. Mitsch; Christoph Müller; Ülo Niinemets; Bruce Osborne; Taavi Pae; Jüri-Ott Salm; Fotis Sgouridis; Kristina Sohar; Kaido Soosaar; Kathryn Storey; Alar Teemusk; Moses M. Tenywa; Julien Tournebize; Jaak Truu; Gert Veber; Jorge A. Villa; Seint Sann Zaw; Ülo Mander. 2018. "Nitrogen-rich organic soils under warm well-drained conditions are global nitrous oxide emission hotspots." Nature Communications 9, no. 1: 1135.
The main aim of the current study was to estimate the annual net nitrogen mineralization (NNM) flux in stands of different tree species growing on drained peatlands, as well as to clarify the effect of tree species, soil properties and litter on annual NNM dynamics. Three study sites were set up in May 2014: a downy birch ( Ehrh.) stand and a Norway spruce ( (L.) Karst.) stand in full-drained swamp (ODS) and a Scots pine ( L.) stand in full-drained swamp (MDS). The NNM flux was estimated using the method with incubated polyethylene bags. The highest value of NNM was found in stands that were growing on fertile ODS: 127.5 kg N ha yr and 87.7 kg N ha yr, in the downy birch stand and in the Norway spruce stand, respectively. A significantly lower annual NNM flux (11.8 kg N ha yr) occurred in the Scots pine stand growing in MDS. Nitrification was highest at fertile ODS sites and ammonification was the highest at the low fertility MDS site. For all study sites, positive correlation was found between soil temperature and NNM intensity. The difference in annual NNM between the downy birch stand and the Norway spruce stand growing on similar drained fertile peatlands was due to litter quality. The annual N input into the soil through leaf litter was the highest at the downy birch site where also the C/N ratio of litter was the lowest. The second highest N input into the soil was found in the spruce stand and the lowest in the pine stand.Betula pubescensPicea abiesOxalisPinus sylvestrisMyrtillusin situâ1â1â1â1â1â1
Hardo Becker; Jürgen Aosaar; Mats Varik; Gunnar Morozov; Kristiina Aun; Ülo Mander; Kaido Soosaar; Veiko Uri. Annual net nitrogen mineralization and litter flux in well-drained downy birch, Norway spruce and Scots pine forest ecosystems. Silva Fennica 2018, 52, 1 .
AMA StyleHardo Becker, Jürgen Aosaar, Mats Varik, Gunnar Morozov, Kristiina Aun, Ülo Mander, Kaido Soosaar, Veiko Uri. Annual net nitrogen mineralization and litter flux in well-drained downy birch, Norway spruce and Scots pine forest ecosystems. Silva Fennica. 2018; 52 (4):1.
Chicago/Turabian StyleHardo Becker; Jürgen Aosaar; Mats Varik; Gunnar Morozov; Kristiina Aun; Ülo Mander; Kaido Soosaar; Veiko Uri. 2018. "Annual net nitrogen mineralization and litter flux in well-drained downy birch, Norway spruce and Scots pine forest ecosystems." Silva Fennica 52, no. 4: 1.
Raili Torga; Ülo Mander; Kaido Soosaar; Priit Kupper; Arvo Tullus; Katrin Rosenvald; Ivika Ostonen; Sander Kutti; Jaak Jaagus; Jaak Sõber; Martin Maddison; Ants Kaasik; Krista Lõhmus. Weather extremes and tree species shape soil greenhouse gas fluxes in an experimental fast-growing deciduous forest of air humidity manipulation. Ecological Engineering 2017, 106, 369 -377.
AMA StyleRaili Torga, Ülo Mander, Kaido Soosaar, Priit Kupper, Arvo Tullus, Katrin Rosenvald, Ivika Ostonen, Sander Kutti, Jaak Jaagus, Jaak Sõber, Martin Maddison, Ants Kaasik, Krista Lõhmus. Weather extremes and tree species shape soil greenhouse gas fluxes in an experimental fast-growing deciduous forest of air humidity manipulation. Ecological Engineering. 2017; 106 ():369-377.
Chicago/Turabian StyleRaili Torga; Ülo Mander; Kaido Soosaar; Priit Kupper; Arvo Tullus; Katrin Rosenvald; Ivika Ostonen; Sander Kutti; Jaak Jaagus; Jaak Sõber; Martin Maddison; Ants Kaasik; Krista Lõhmus. 2017. "Weather extremes and tree species shape soil greenhouse gas fluxes in an experimental fast-growing deciduous forest of air humidity manipulation." Ecological Engineering 106, no. : 369-377.
Estimation of the carbon (C) storages and fluxes in different forest ecosystems is essential for understanding their C sequestration ability. Grey alder (Alnus incana (L.) Moench) is a fast growing tree species with a great potential for short-rotation forestry in the Nordic and Baltic countries and its stands are considered C accumulating ecosystems. We hypothesized that grey alder stands growing at fertile sites act as C sinks in the young and middle-age stages, while mature stands become C sources as a consequence of declined net primary production (NPP). Net ecosystem production (NEP) was studied in five grey alder stands aged between 9 and 40 years. It was found that the NEP of the studied grey alder stands of different ages varied from −1.98 to +4.14 t C ha−1 yr−1. The oldest grey alder stand proved to be a weak C source (−0.77 t C ha−1 yr−1). However, also young alder stands regenerated in a clear-cut area may emit C in the earlier stage, owing to previous cutting and decomposition of organic residues matter. In this aspect, the land use history is of great significance. Leaf litter accounted for the largest (44–61%) annual organic C input to soil, the fine roots contributed with 12–32% and the herbaceous understorey (aboveground + belowground), with 14–26% to it. Annual cumulative soil heterotrophic respiration (Rh) in the studied stands ranged between 2.6 and 5.8 t C ha−1 yr−1; C leaching was negligible, being 10–30 kg C ha−1 yr−1. The C sequestration to soil depended on previous land use; in the first forest generation, i.e. a stand growing on previous agricultural land, the annual Corg input into soil exceeded Rh, which indicated C accumulation in soil. Although grey alder stands are generally C accumulating ecosystems, the annual biomass production of the studied stands was highly variable; thus annual NEP depended on the effect of the year rather than on stand age. The current study demonstrates that use of repeated time-series measurements applied for stands of different development stages can provide more detailed estimation of C accumulation in forest ecosystems.
V. Uri; Mai Kukumägi; J. Aosaar; M. Varik; H. Becker; K. Soosaar; Gunnar Morozov; K. Ligi; A. Padari; I. Ostonen; K. Karoles. Carbon budgets in fertile grey alder (Alnus incana (L.) Moench.) stands of different ages. Forest Ecology and Management 2017, 396, 55 -67.
AMA StyleV. Uri, Mai Kukumägi, J. Aosaar, M. Varik, H. Becker, K. Soosaar, Gunnar Morozov, K. Ligi, A. Padari, I. Ostonen, K. Karoles. Carbon budgets in fertile grey alder (Alnus incana (L.) Moench.) stands of different ages. Forest Ecology and Management. 2017; 396 ():55-67.
Chicago/Turabian StyleV. Uri; Mai Kukumägi; J. Aosaar; M. Varik; H. Becker; K. Soosaar; Gunnar Morozov; K. Ligi; A. Padari; I. Ostonen; K. Karoles. 2017. "Carbon budgets in fertile grey alder (Alnus incana (L.) Moench.) stands of different ages." Forest Ecology and Management 396, no. : 55-67.
Peatland restoration may provide a potential after-use option to mitigate the negative climate impact of abandoned peat extraction areas; currently, however, knowledge about restoration effects on the annual balances of carbon (C) and greenhouse gas (GHG) exchanges is still limited. The aim of this study was to investigate the impact of contrasting mean water table levels (WTLs) on the annual C and GHG balances of restoration treatments with high (ResH) and low (ResL) WTL relative to an unrestored bare peat (BP) site. Measurements of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes were conducted over a full year using the closed chamber method and complemented by measurements of abiotic controls and vegetation cover. Three years following restoration, the difference in the mean WTL resulted in higher bryophyte and lower vascular plant cover in ResH relative to ResL. Consequently, greater gross primary production and autotrophic respiration associated with greater vascular plant cover were observed in ResL compared to ResH. However, the means of the measured net ecosystem CO2 exchanges (NEE) were not significantly different between ResH and ResL. Similarly, no significant differences were observed in the respective means of CH4 and N2O exchanges. In comparison to the two restored sites, greater net CO2, similar CH4 and greater N2O emissions occurred in BP. On the annual scale, ResH, ResL and BP were C sources of 111, 103 and 268 g C m−2 yr−1 and had positive GHG balances of 4.1, 3.8 and 10.2 t CO2 eq ha−1 yr−1, respectively. Thus, the different WTLs had a limited impact on the C and GHG balances in the two restored treatments 3 years following restoration. However, the C and GHG balances in ResH and ResL were considerably lower than in BP due to the large reduction in CO2 emissions. This study therefore suggests that restoration may serve as an effective method to mitigate the negative climate impacts of abandoned peat extraction areas.
Järvi Järveoja; Matthias Peichl; Martin Maddison; Kaido Soosaar; Kai Vellak; Edgar Karofeld; Alar Teemusk; Ülo Mander. Impact of water table level on annual carbon and greenhouse gas balances of a restored peat extraction area. Biogeosciences 2016, 13, 2637 -2651.
AMA StyleJärvi Järveoja, Matthias Peichl, Martin Maddison, Kaido Soosaar, Kai Vellak, Edgar Karofeld, Alar Teemusk, Ülo Mander. Impact of water table level on annual carbon and greenhouse gas balances of a restored peat extraction area. Biogeosciences. 2016; 13 (9):2637-2651.
Chicago/Turabian StyleJärvi Järveoja; Matthias Peichl; Martin Maddison; Kaido Soosaar; Kai Vellak; Edgar Karofeld; Alar Teemusk; Ülo Mander. 2016. "Impact of water table level on annual carbon and greenhouse gas balances of a restored peat extraction area." Biogeosciences 13, no. 9: 2637-2651.
Grey alder is a wide spread tree species in the Baltic region and a promising species for short rotation forestry. The symbiotic dinitrogen (N2) fixation ability makes this tree important for the regulation of nitrogen (N) cycle in forested areas. In a homogeneous 32-year-old natural grey alder stand (GAS) and an adjacent clear-cut (CC) in South-East Estonia (58°17′ N; 27°17′ E; set up in May 2011) we analyzed net nitrogen mineralization (NNM; with incubated bags), N leaching (with plate lysimeters), and nitrous oxide (N2O) fluxes (with static chambers). The total annual NNM did not intensify in the CC area: in the upper 0–20 cm soil layer the NNM was 169.9 and 157.0 kg ha−1 in the (GAS) and in the CC, respectively. In both cases, the share of nitrification was 100% and NNM intensity was the highest in July. During the snow-melt in April, both in the GAS and in the CC site the leaching of total N was up to 25 kg N month−1, whereas in the rest of study period it was negligible in both sites. Harvesting slightly decreased N2O emission, however, it was low at both study sites (−0.55 to 19.75 and −0.77 to 7.43 kg N2O ha−1 yr−1 in the GAS and the CC, respectively). Management of grey alder stands by traditional silvicultural methods (clear-cuts) did not to increased hazardous N losses through leaching.
Hardo Becker; Veiko Uri; Jürgen Aosaar; Mats Varik; Ülo Mander; Kaido Soosaar; Raili Hansen; Alar Teemusk; Gunnar Morozov; Sander Kutti; Krista Lõhmus. The effects of clear-cut on net nitrogen mineralization and nitrogen losses in a grey alder stand. Ecological Engineering 2015, 85, 237 -246.
AMA StyleHardo Becker, Veiko Uri, Jürgen Aosaar, Mats Varik, Ülo Mander, Kaido Soosaar, Raili Hansen, Alar Teemusk, Gunnar Morozov, Sander Kutti, Krista Lõhmus. The effects of clear-cut on net nitrogen mineralization and nitrogen losses in a grey alder stand. Ecological Engineering. 2015; 85 ():237-246.
Chicago/Turabian StyleHardo Becker; Veiko Uri; Jürgen Aosaar; Mats Varik; Ülo Mander; Kaido Soosaar; Raili Hansen; Alar Teemusk; Gunnar Morozov; Sander Kutti; Krista Lõhmus. 2015. "The effects of clear-cut on net nitrogen mineralization and nitrogen losses in a grey alder stand." Ecological Engineering 85, no. : 237-246.
Ülo Mander; Martin Maddison; Kaido Soosaar; Helen Koger; Alar Teemusk; Jaak Truu; Reinhard Well; Mathieu Sebilo. The impact of a pulsing water table on wastewater purification and greenhouse gas emission in a horizontal subsurface flow constructed wetland. Ecological Engineering 2015, 80, 69 -78.
AMA StyleÜlo Mander, Martin Maddison, Kaido Soosaar, Helen Koger, Alar Teemusk, Jaak Truu, Reinhard Well, Mathieu Sebilo. The impact of a pulsing water table on wastewater purification and greenhouse gas emission in a horizontal subsurface flow constructed wetland. Ecological Engineering. 2015; 80 ():69-78.
Chicago/Turabian StyleÜlo Mander; Martin Maddison; Kaido Soosaar; Helen Koger; Alar Teemusk; Jaak Truu; Reinhard Well; Mathieu Sebilo. 2015. "The impact of a pulsing water table on wastewater purification and greenhouse gas emission in a horizontal subsurface flow constructed wetland." Ecological Engineering 80, no. : 69-78.
Known as biogeochemical hotspots in landscapes, riparian buffer zones exhibit considerable potential concerning mitigation of groundwater contaminants such as nitrate, but may in return enhance the risk for indirect N2O emission. Here we aim to assess and to compare two riparian gray alder forests in terms of gaseous N2O and N2 fluxes and dissolved N2O, N2, and NO3(-) in the near-surface groundwater. We further determine for the first time isotopologue ratios of N2O dissolved in the riparian groundwater in order to support our assumption that it mainly originated from denitrification. The study sites, both situated in Estonia, northeastern Europe, receive contrasting N loads from adjacent uphill arable land. Whereas N2O emissions were rather small at both sites, average gaseous N2-to-N2O ratios inferred from closed-chamber measurements and He-O laboratory incubations were almost four times smaller for the heavily loaded site. In contrast, groundwater parameters were less variable among sites and between landscape positions. Campaign-based average (15)N site preferences of N2O (SP) in riparian groundwater ranged between 11 and 44 ‰. Besides the strong prevalence of N2 emission over N2O fluxes and the correlation pattern between isotopologue and water quality data, this comparatively large range highlights the importance of denitrification and N2O reduction in both riparian gray alder stands.
Ulo Mander; Reinhard Well; Daniel Weymann; Kaido Soosaar; Martin Maddison; Arno Kanal; Krista Löhmus; Jaak Truu; Jürgen Augustin; Julien Tournebize. Isotopologue Ratios of N2O and N2Measurements Underpin the Importance of Denitrification in Differently N-Loaded Riparian Alder Forests. Environmental Science & Technology 2014, 48, 11910 -11918.
AMA StyleUlo Mander, Reinhard Well, Daniel Weymann, Kaido Soosaar, Martin Maddison, Arno Kanal, Krista Löhmus, Jaak Truu, Jürgen Augustin, Julien Tournebize. Isotopologue Ratios of N2O and N2Measurements Underpin the Importance of Denitrification in Differently N-Loaded Riparian Alder Forests. Environmental Science & Technology. 2014; 48 (20):11910-11918.
Chicago/Turabian StyleUlo Mander; Reinhard Well; Daniel Weymann; Kaido Soosaar; Martin Maddison; Arno Kanal; Krista Löhmus; Jaak Truu; Jürgen Augustin; Julien Tournebize. 2014. "Isotopologue Ratios of N2O and N2Measurements Underpin the Importance of Denitrification in Differently N-Loaded Riparian Alder Forests." Environmental Science & Technology 48, no. 20: 11910-11918.
Floods control greenhouse gas (GHG) emissions in floodplains; however, there is a lack of data on the impact of short-term events on emissions. We studied the short-term effect of changing groundwater (GW) depth on the emission of (GHG) carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) in two riparian grey alder (Alnus incana) stands of different age in Kambja, southern Estonia, using the opaque static chamber (five replicates in each site) and gas chromatography methods. The average carbon and total nitrogen content in the soil of the old alder (OA) stand was significantly higher than in the young alder (YA) stand. In both stands, one part was chosen for water table manipulation (Manip) and another remained unchanged with a stable and deeper GW table. Groundwater table manipulation (flooding) significantly increases CH4 emission (average: YA-Dry 468, YA-Manip 8,374, OA-Dry 468, OA-Manip 4,187 μg C m−2 h−1) and decreases both CO2 (average: OA-Dry 138, OA-Manip 80 mg C m−2 h−1) and N2O emissions (average: OA-Dry 23.1, OA-Manip 11.8 μg N m−2 h−1) in OA sites. There was no significant difference in CO2 and CH4 emissions between the OA and YA sites, whereas in OA sites with higher N concentration in the soil, the N2O emission was significantly higher than at the YA sites. The relative CO2 and CH4 emissions (the soil C stock-related share of gaseous losses) were higher in manipulated plots showing the highest values in the YA-Manip plot (0.03 and 0.0030 % C day−1, respectively). The soil N stock-related N2O emission was very low achieving 0.000019 % N day−1 in the OA-Dry plot. Methane emission shows a negative correlation with GW, whereas the 20 cm depth is a significant limit below which most of the produced CH4 is oxidized. In terms of CO2 and N2O, the deeper GW table significantly increases emission. In riparian zones of headwater streams, the short-term floods (e.g. those driven by extreme climate events) may significantly enhance methane emission whereas the long-term lowering of the groundwater table is a more important initiator of N2O fluxes from riparian gley soils than flood pulses.
Ülo Mander; Martin Maddison; Kaido Soosaar; Alar Teemusk; Arno Kanal; Veiko Uri; Jaak Truu. The impact of a pulsing groundwater table on greenhouse gas emissions in riparian grey alder stands. Environmental Science and Pollution Research 2014, 22, 2360 -2371.
AMA StyleÜlo Mander, Martin Maddison, Kaido Soosaar, Alar Teemusk, Arno Kanal, Veiko Uri, Jaak Truu. The impact of a pulsing groundwater table on greenhouse gas emissions in riparian grey alder stands. Environmental Science and Pollution Research. 2014; 22 (4):2360-2371.
Chicago/Turabian StyleÜlo Mander; Martin Maddison; Kaido Soosaar; Alar Teemusk; Arno Kanal; Veiko Uri; Jaak Truu. 2014. "The impact of a pulsing groundwater table on greenhouse gas emissions in riparian grey alder stands." Environmental Science and Pollution Research 22, no. 4: 2360-2371.
Predicting N2O (nitrous oxide) and CH4 (methane) emissions from peatlands is challenging because of the complex coaction of biogeochemical factors. This study uses data from a global soil and gas sampling campaign. The objective is to analyse N2O and CH4 emissions in terms of peat physical and chemical conditions. Our study areas were evenly distributed across the A, C and D climates of the Köppen classification. Gas measurements using static chambers, groundwater analysis and gas and peat sampling for further laboratory analysis have been conducted in 13 regions evenly distributed across the globe. In each study area at least two study sites were established. Each site featured at least three sampling plots, three replicate chambers and corresponding soil pits and one observation well per plot. Gas emissions were measured during 2–3 days in at least three sessions. A log-log linear function limits N2O emissions in relation to soil TIN (total inorganic nitrogen). The boundary line of N2O in terms of soil temperature is semilog linear. The closest representation of the relationship between N2O and soil moisture is a local regression curve with its optimum at 60–70 %. Semilog linear upper boundaries describe the effects of soil moisture and soil temperature to CH4 best.
Jaan Pärn; Anto Aasa; Sergey Egorov; Ilya Filippov; Geofrey Gabiri; Iuliana Gheorghe; Järvi Järveoja; Kuno Kasak; Fatima Laggoun-Defarge; Charles Kizza Luswata; Martin Maddison; William J. Mitsch; Hlynur Oskarsson; Stéphanie Pellerin; Jüri-Ott Salm; Kristina Sohar; Kaido Soosaar; Alar Teemusk; Moses M. Tenywa; Jorge A. Villa; Christina Vohla; Ulo Mander. Global Boundary Lines of N2O and CH4 Emission in Peatlands. The Role of Natural and Constructed Wetlands in Nutrient Cycling and Retention on the Landscape 2014, 87 -102.
AMA StyleJaan Pärn, Anto Aasa, Sergey Egorov, Ilya Filippov, Geofrey Gabiri, Iuliana Gheorghe, Järvi Järveoja, Kuno Kasak, Fatima Laggoun-Defarge, Charles Kizza Luswata, Martin Maddison, William J. Mitsch, Hlynur Oskarsson, Stéphanie Pellerin, Jüri-Ott Salm, Kristina Sohar, Kaido Soosaar, Alar Teemusk, Moses M. Tenywa, Jorge A. Villa, Christina Vohla, Ulo Mander. Global Boundary Lines of N2O and CH4 Emission in Peatlands. The Role of Natural and Constructed Wetlands in Nutrient Cycling and Retention on the Landscape. 2014; ():87-102.
Chicago/Turabian StyleJaan Pärn; Anto Aasa; Sergey Egorov; Ilya Filippov; Geofrey Gabiri; Iuliana Gheorghe; Järvi Järveoja; Kuno Kasak; Fatima Laggoun-Defarge; Charles Kizza Luswata; Martin Maddison; William J. Mitsch; Hlynur Oskarsson; Stéphanie Pellerin; Jüri-Ott Salm; Kristina Sohar; Kaido Soosaar; Alar Teemusk; Moses M. Tenywa; Jorge A. Villa; Christina Vohla; Ulo Mander. 2014. "Global Boundary Lines of N2O and CH4 Emission in Peatlands." The Role of Natural and Constructed Wetlands in Nutrient Cycling and Retention on the Landscape , no. : 87-102.
Abandoned peat extraction areas are continuous emitters of GHGs; hence, abandonment of peat extraction areas should immediately be followed by conversion to an appropriate after-use. Our primary aim was to clarify the atmospheric impact of reed canary grass (RCG, Phalaris arundinacea L.) cultivation on an abandoned peat extraction area and to compare it to other after-treatment alternatives. We performed a life-cycle assessment for five different after-use options for a drained organic soil withdrawn from peat extraction: (I) bare peat soil (no management), (II) non-fertilised Phalaris cultivation, (III) fertilised Phalaris cultivation, (IV) afforestation, and (V) rewetting. Our results showed that on average the non-fertilised and fertilised Phalaris alternatives had a cooling effect on the atmosphere (−10,837 and −477 kg CO2-eq ha−1 year−1, respectively), whereas afforestation, rewetting, and no-management alternatives contributed to global warming (9,511, 8,195, and 2,529 kg CO2-eq ha−1 year−1, respectively). The main components influencing the global warming potential of different after-use alternatives were site GHG emissions, carbon assimilation by plants, and emissions from combustion, while management-related emissions played a relatively minor role. The results of this study indicate that, from the perspective of atmospheric impact, the most suitable after-use option for an abandoned peat extraction area is cultivation of RCG.
Järvi Järveoja; Janika Laht; Martin Maddison; Kaido Soosaar; Ivika Ostonen; Ülo Mander. Mitigation of greenhouse gas emissions from an abandoned Baltic peat extraction area by growing reed canary grass: life-cycle assessment. Regional Environmental Change 2012, 13, 781 -795.
AMA StyleJärvi Järveoja, Janika Laht, Martin Maddison, Kaido Soosaar, Ivika Ostonen, Ülo Mander. Mitigation of greenhouse gas emissions from an abandoned Baltic peat extraction area by growing reed canary grass: life-cycle assessment. Regional Environmental Change. 2012; 13 (4):781-795.
Chicago/Turabian StyleJärvi Järveoja; Janika Laht; Martin Maddison; Kaido Soosaar; Ivika Ostonen; Ülo Mander. 2012. "Mitigation of greenhouse gas emissions from an abandoned Baltic peat extraction area by growing reed canary grass: life-cycle assessment." Regional Environmental Change 13, no. 4: 781-795.