50 results on '"Rinne, Janne"'
Search Results
2. Strong isoprene emission response to temperature in tundra vegetation
- Author
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Seco, Roger, Holst, Thomas, Davie-Martin, Cleo L, Simin, Tihomir, Guenther, Alex, Pirk, Norbert, Rinne, Janne, and Rinnan, Riikka
- Subjects
Earth Sciences ,Atmospheric Sciences ,Climate Action ,Butadienes ,Global Warming ,Hemiterpenes ,Plant Development ,Temperature ,Tundra ,Volatile Organic Compounds ,biosphere-atmosphere interactions ,biogenic volatile organic compound fluxes ,temperature response ,VOC emission modeling ,eddy covariance ,biosphere–atmosphere interactions - Abstract
Emissions of biogenic volatile organic compounds (BVOCs) are a crucial component of biosphere-atmosphere interactions. In northern latitudes, climate change is amplified by feedback processes in which BVOCs have a recognized, yet poorly quantified role, mainly due to a lack of measurements and concomitant modeling gaps. Hence, current Earth system models mostly rely on temperature responses measured on vegetation from lower latitudes, rendering their predictions highly uncertain. Here, we show how tundra isoprene emissions respond vigorously to temperature increases, compared to model results. Our unique dataset of direct eddy covariance ecosystem-level isoprene measurements in two contrasting ecosystems exhibited Q10 (the factor by which the emission rate increases with a 10 °C rise in temperature) temperature coefficients of up to 20.8, that is, 3.5 times the Q10 of 5.9 derived from the equivalent model calculations. Crude estimates using the observed temperature responses indicate that tundra vegetation could enhance their isoprene emissions by up to 41% (87%)-that is, 46% (55%) more than estimated by models-with a 2 °C (4 °C) warming. Our results demonstrate that tundra vegetation possesses the potential to substantially boost its isoprene emissions in response to future rising temperatures, at rates that exceed the current Earth system model predictions.
- Published
- 2022
3. Terpene emissions from boreal wetlands can initiate stronger atmospheric new particle formation than boreal forests
- Author
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Junninen, Heikki, Ahonen, Lauri, Bianchi, Federico, Quéléver, Lauriane, Schallhart, Simon, Dada, Lubna, Manninen, Hanna Elina, Leino, Katri, Lampilahti, Janne, Buenrostro Mazon, Stephany, Rantala, Pekka, Räty, Mari, Kontkanen, Jenni, Negri, Sara, Aliaga, Diego, Garmash, Olga, Alekseychik, Pavel, Lipp, Helina, Tamme, Kalju, Levula, Janne, Sipilä, Mikko, Ehn, Mikael, Worsnop, Douglas, Zilitinkevich, Sergej, Mammarella, Ivan, Rinne, Janne, Vesala, Timo, Petäjä, Tuukka, Kerminen, Veli-Matti, and Kulmala, Markku
- Published
- 2022
- Full Text
- View/download PDF
4. Assimilating Multi-site Eddy-Covariance Data to Calibrate the CH4 Wetland Emission Module in a Terrestrial Ecosystem Model
- Author
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Kallingal, Jalisha Theanutti, primary, Scholze, Marko, additional, Miller, Paul Anthony, additional, Lindström, Johan, additional, Rinne, Janne, additional, Aurela, Mika, additional, Vestin, Patrik, additional, and Weslien, Per, additional
- Published
- 2024
- Full Text
- View/download PDF
5. Soil greenhouse gas emissions from a sisal chronosequence in Kenya
- Author
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Wachiye, Sheila, Merbold, Lutz, Vesala, Timo, Rinne, Janne, Leitner, Sonja, Räsänen, Matti, Vuorinne, Ilja, Heiskanen, Janne, and Pellikka, Petri
- Published
- 2021
- Full Text
- View/download PDF
6. Optimising CH4 simulations from the LPJ-GUESS model v4.1 using an adaptive Markov chain Monte Carlo algorithm.
- Author
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Kallingal, Jalisha T., Lindström, Johan, Miller, Paul A., Rinne, Janne, Raivonen, Maarit, and Scholze, Marko
- Subjects
METHANE ,COST functions ,MEASUREMENT errors ,MARKOV chain Monte Carlo - Abstract
The processes responsible for methane (CH4) emissions from boreal wetlands are complex; hence, their model representation is complicated by a large number of parameters and parameter uncertainties. The arctic-enabled dynamic global vegetation model LPJ-GUESS (Lund–Potsdam–Jena General Ecosystem Simulator) is one such model that allows quantification and understanding of the natural wetland CH4 fluxes at various scales, ranging from local to regional and global, but with several uncertainties. The model contains detailed descriptions of the CH4 production, oxidation, and transport controlled by several process parameters. Complexities in the underlying environmental processes, warming-driven alternative paths of meteorological phenomena, and changes in hydrological and vegetation conditions highlight the need for a calibrated and optimised version of LPJ-GUESS. In this study, we formulated the parameter calibration as a Bayesian problem, using knowledge of reasonable parameters values as priors. We then used an adaptive Metropolis–Hastings (MH)-based Markov chain Monte Carlo (MCMC) algorithm to improve predictions of CH4 emission by LPJ-GUESS and to quantify uncertainties. Application of this method on uncertain parameters allows for a greater search of their posterior distribution, leading to a more complete characterisation of the posterior distribution with a reduced risk of the sample impoverishment that can occur when using other optimisation methods. For assimilation, the analysis used flux measurement data gathered during the period from 2005 to 2014 from the Siikaneva wetlands in Southern Finland with an estimation of measurement uncertainties. The data are used to constrain the processes behind the CH4 dynamics, and the posterior covariance structures are used to explain how the parameters and the processes are related. To further support the conclusions, the CH4 flux and the other component fluxes associated with the flux are examined. The results demonstrate the robustness of MCMC methods to quantitatively assess the interrelationship between objective function choices, parameter identifiability, and data support. The experiment using real observations from Siikaneva resulted in a reduction in the root-mean-square error (RMSE), from 0.044 to 0.023 gC m -2 d -1 , and a 93.89 % reduction in the cost function value. As a part of this work, knowledge about how CH4 data can constrain the parameters and processes is derived. Although the optimisation is performed based on a single site's flux data from Siikaneva, the algorithm is useful for larger-scale multi-site studies for a more robust calibration of LPJ-GUESS and similar models, and the results can highlight where model improvements are needed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
7. Substantial hysteresis in emergent temperature sensitivity of global wetland CH4 emissions
- Author
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Chang, Kuang-Yu, Riley, William J., Knox, Sara H., Jackson, Robert B., McNicol, Gavin, Poulter, Benjamin, Aurela, Mika, Baldocchi, Dennis, Bansal, Sheel, Bohrer, Gil, Campbell, David I., Cescatti, Alessandro, Chu, Housen, Delwiche, Kyle B., Desai, Ankur R., Euskirchen, Eugenie, Friborg, Thomas, Goeckede, Mathias, Helbig, Manuel, Hemes, Kyle S., Hirano, Takashi, Iwata, Hiroki, Kang, Minseok, Keenan, Trevor, Krauss, Ken W., Lohila, Annalea, Mammarella, Ivan, Mitra, Bhaskar, Miyata, Akira, Nilsson, Mats B., Noormets, Asko, Oechel, Walter C., Papale, Dario, Peichl, Matthias, Reba, Michele L., Rinne, Janne, Runkle, Benjamin R. K., Ryu, Youngryel, Sachs, Torsten, Schäfer, Karina V. R., Schmid, Hans Peter, Shurpali, Narasinha, Sonnentag, Oliver, Tang, Angela C. I., Torn, Margaret S., Trotta, Carlo, Tuittila, Eeva-Stiina, Ueyama, Masahito, Vargas, Rodrigo, Vesala, Timo, Windham-Myers, Lisamarie, Zhang, Zhen, and Zona, Donatella
- Published
- 2021
- Full Text
- View/download PDF
8. Carbon dioxide and methane fluxes from mounds of African fungus-growing termites
- Author
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Räsänen, Matti, primary, Vesala, Risto, additional, Rönnholm, Petri, additional, Arppe, Laura, additional, Manninen, Petra, additional, Jylhä, Markus, additional, Rikkinen, Jouko, additional, Pellikka, Petri, additional, and Rinne, Janne, additional
- Published
- 2023
- Full Text
- View/download PDF
9. Assimilating Multi-site Eddy-Covariance Data to Calibrate the CH4 Wetland Emission Module in a Terrestrial Ecosystem Model.
- Author
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Kallingal, Jalisha Theanutti, Scholze, Marko, Miller, Paul Anthony, Lindström, Johan, Rinne, Janne, Aurela, Mika, Vestin, Patrik, and Weslien, Per
- Subjects
WETLANDS ,MARKOV chain Monte Carlo ,COST functions ,EDDY flux - Abstract
In this study, we use a data assimilation framework based on the Adaptive Markov Chain Monte Carlo (MCMC) algorithm to constrain process parameters in LPJ-GUESS using CH
4 eddy covariance flux observations from 14 different natural boreal and temperate wetlands. The objective is to derive a single set of calibrated parameter values. These parameters are then used in the model to validate its CH4 flux output against 5 different types of natural wetlands situated in different locations, assessing their generality for simulating CH4 fluxes from different boreal and temperate wetlands. The results show that the MCMC framework has substantially reduced the cost function (measuring the misfit between simulated and observed CH4 fluxes) and facilitated detailed characterisation of the posterior distribution. A reduction of around 95 % in the cost function and approximately 50 % in RMSE were observed. The validation experiment results indicate that four out of 5 sites successfully reduced RMSE, demonstrating the effectiveness of the framework for estimating CH4 emissions from wetlands not included in the study. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
10. High-resolution spatial patterns and drivers of terrestrial ecosystem carbon dioxide, methane, and nitrous oxide fluxes in the tundra.
- Author
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Virkkala, Anna-Maria, Niittynen, Pekka, Kemppinen, Julia, Marushchak, Maija E., Voigt, Carolina, Hensgens, Geert, Kerttula, Johanna, Happonen, Konsta, Tyystjärvi, Vilna, Biasi, Christina, Hultman, Jenni, Rinne, Janne, and Luoto, Miska
- Subjects
TUNDRAS ,CARBON dioxide ,MACHINE learning ,NITROUS oxide ,PLANT biomass ,SOIL temperature - Abstract
Arctic terrestrial greenhouse gas (GHG) fluxes of carbon dioxide (CO 2), methane (CH 4), and nitrous oxide (N 2 O) play an important role in the global GHG budget. However, these GHG fluxes are rarely studied simultaneously, and our understanding of the conditions controlling them across spatial gradients is limited. Here, we explore the magnitudes and drivers of GHG fluxes across fine-scale terrestrial gradients during the peak growing season (July) in sub-Arctic Finland. We measured chamber-derived GHG fluxes and soil temperature, soil moisture, soil organic carbon and nitrogen stocks, soil pH, soil carbon-to-nitrogen (C/N) ratio, soil dissolved organic carbon content, vascular plant biomass, and vegetation type from 101 plots scattered across a heterogeneous tundra landscape (5 km 2). We used these field data together with high-resolution remote sensing data to develop machine learning models for predicting (i.e., upscaling) daytime GHG fluxes across the landscape at 2 m resolution. Our results show that this region was on average a daytime net GHG sink during the growing season. Although our results suggest that this sink was driven by CO 2 uptake, it also revealed small but widespread CH 4 uptake in upland vegetation types, almost surpassing the high wetland CH 4 emissions at the landscape scale. Average N 2 O fluxes were negligible. CO 2 fluxes were controlled primarily by annual average soil temperature and biomass (both increase net sink) and vegetation type, CH 4 fluxes by soil moisture (increases net emissions) and vegetation type, and N 2 O fluxes by soil C/N (lower C/N increases net source). These results demonstrate the potential of high spatial resolution modeling of GHG fluxes in the Arctic. They also reveal the dominant role of CO 2 fluxes across the tundra landscape but suggest that CH 4 uptake in dry upland soils might play a significant role in the regional GHG budget. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
11. Vertical distribution of sources and sinks of volatile organic compounds within a boreal forest canopy
- Author
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Petersen, Ross, primary, Holst, Thomas, additional, Mölder, Meelis, additional, Kljun, Natascha, additional, and Rinne, Janne, additional
- Published
- 2023
- Full Text
- View/download PDF
12. Optimising CH4 simulations from the LPJ-GUESS model v4.1 using an adaptive MCMC algorithm
- Author
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Kallingal, Jalisha Theanutti, primary, Lindström, Johan, additional, Miller, Paul A, additional, Rinne, Janne, additional, Raivonen, Maarit, additional, and Scholze, Marko, additional
- Published
- 2023
- Full Text
- View/download PDF
13. Supplementary material to "Optimising CH4 simulations from the LPJ-GUESS model v4.1 using an adaptive MCMC algorithm"
- Author
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Kallingal, Jalisha Theanutti, primary, Lindström, Johan, additional, Miller, Paul A, additional, Rinne, Janne, additional, Raivonen, Maarit, additional, and Scholze, Marko, additional
- Published
- 2023
- Full Text
- View/download PDF
14. High-resolution spatial patterns and drivers of terrestrial ecosystem carbon dioxide, methane, and nitrous oxide fluxes in the tundra
- Author
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Virkkala, Anna-Maria, primary, Niittynen, Pekka, additional, Kemppinen, Julia, additional, Marushchak, Maija E., additional, Voigt, Carolina, additional, Hensgens, Geert, additional, Kerttula, Johanna, additional, Happonen, Konsta, additional, Tyystjärvi, Vilna, additional, Biasi, Christina, additional, Hultman, Jenni, additional, Rinne, Janne, additional, and Luoto, Miska, additional
- Published
- 2023
- Full Text
- View/download PDF
15. Supplementary material to "High-resolution spatial patterns and drivers of terrestrial ecosystem carbon dioxide, methane, and nitrous oxide fluxes in the tundra"
- Author
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Virkkala, Anna-Maria, primary, Niittynen, Pekka, additional, Kemppinen, Julia, additional, Marushchak, Maija E., additional, Voigt, Carolina, additional, Hensgens, Geert, additional, Kerttula, Johanna, additional, Happonen, Konsta, additional, Tyystjärvi, Vilna, additional, Biasi, Christina, additional, Hultman, Jenni, additional, Rinne, Janne, additional, and Luoto, Miska, additional
- Published
- 2023
- Full Text
- View/download PDF
16. Assessing CO2 and CH4 fluxes from mounds of African fungus-growing termites
- Author
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Räsänen, Matti, primary, Vesala, Risto, additional, Rönnholm, Petri, additional, Arppe, Laura, additional, Manninen, Petra, additional, Jylhä, Markus, additional, Rikkinen, Jouko, additional, Pellikka, Petri, additional, and Rinne, Janne, additional
- Published
- 2023
- Full Text
- View/download PDF
17. Supplementary material to "Assessing CO2 and CH4 fluxes from mounds of African fungus-growing termites"
- Author
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Räsänen, Matti, primary, Vesala, Risto, additional, Rönnholm, Petri, additional, Arppe, Laura, additional, Manninen, Petra, additional, Jylhä, Markus, additional, Rikkinen, Jouko, additional, Pellikka, Petri, additional, and Rinne, Janne, additional
- Published
- 2023
- Full Text
- View/download PDF
18. Impacts of innovation environments: SmartRail Ecosystem & Mobility Lab Helsinki
- Author
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Lusikka, Toni, Kostiainen, Juho, Rinne, Janne, and Hautala, Raine
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innovation environment ,impact evaluation ,co-creation - Abstract
This paper describes impacts of and experiences from two co-creative innovation environments, the SmartRail Ecosystem and Mobility Lab Helsinki. These innovation environments are investigated and compared to see what similarities and differences the environments have, and furthermore, what kinds of gained benefits and other impacts the environments have produced for different actors. The paper discusses how impacts of ecosystems and enabling innovation collaboration can be evaluated and what is the value of co-creation environments.
- Published
- 2023
19. Seasonal and spatial variation in 13C signature of emitted methane and pore water methane in northern mires
- Author
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Rinne, Janne, primary, Li, Xuefei, additional, Łakomiec, Patryk, additional, Vestin, Patrik, additional, Weslien, Per, additional, Kelly, Julia, additional, Kohl, Lukas, additional, Ström, Lena, additional, Vesala, Timo, additional, and Klemedtsson, Leif, additional
- Published
- 2023
- Full Text
- View/download PDF
20. Eddy covariance observations of CO2, CH4 and N2O fluxes of a drained boreal peatland forest after clear-cutting
- Author
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Peltola, Olli, primary, Tikkasalo, Olli-Pekka, additional, Alekseychik, Pavel, additional, Launiainen, Samuli, additional, Lehtonen, Aleksi, additional, Li, Qian, additional, Peltoniemi, Mikko, additional, Rinne, Janne, additional, Rissanen, Antti, additional, Sarkkola, Sakari, additional, and Mäkipää, Raisa, additional
- Published
- 2023
- Full Text
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21. Carbon uptake in Eurasian boreal forests dominates the high‐latitude net ecosystem carbon budget
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Watts, Jennifer D., primary, Farina, Mary, additional, Kimball, John S., additional, Schiferl, Luke D., additional, Liu, Zhihua, additional, Arndt, Kyle A., additional, Zona, Donatella, additional, Ballantyne, Ashley, additional, Euskirchen, Eugénie S., additional, Parmentier, Frans‐Jan W., additional, Helbig, Manuel, additional, Sonnentag, Oliver, additional, Tagesson, Torbern, additional, Rinne, Janne, additional, Ikawa, Hiroki, additional, Ueyama, Masahito, additional, Kobayashi, Hideki, additional, Sachs, Torsten, additional, Nadeau, Daniel F., additional, Kochendorfer, John, additional, Jackowicz‐Korczynski, Marcin, additional, Virkkala, Anna, additional, Aurela, Mika, additional, Commane, Roisin, additional, Byrne, Brendan, additional, Birch, Leah, additional, Johnson, Matthew S., additional, Madani, Nima, additional, Rogers, Brendan, additional, Du, Jinyang, additional, Endsley, Arthur, additional, Savage, Kathleen, additional, Poulter, Ben, additional, Zhang, Zhen, additional, Bruhwiler, Lori M., additional, Miller, Charles E., additional, Goetz, Scott, additional, and Oechel, Walter C., additional
- Published
- 2023
- Full Text
- View/download PDF
22. Vertical distribution of sources and sinks of VOCs within a boreal forest canopy
- Author
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Petersen, Ross Charles, primary, Holst, Thomas, additional, Mölder, Meelis, additional, Kljun, Natascha, additional, and Rinne, Janne, additional
- Published
- 2022
- Full Text
- View/download PDF
23. The effect of rainfall amount and timing on annual transpiration in a grazed savanna grassland
- Author
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Räsänen, Matti, primary, Aurela, Mika, additional, Vakkari, Ville, additional, Beukes, Johan P., additional, Tuovinen, Juha-Pekka, additional, Van Zyl, Pieter G., additional, Josipovic, Miroslav, additional, Siebert, Stefan J., additional, Laurila, Tuomas, additional, Kulmala, Markku, additional, Laakso, Lauri, additional, Rinne, Janne, additional, Oren, Ram, additional, and Katul, Gabriel, additional
- Published
- 2022
- Full Text
- View/download PDF
24. New contributions of measurements in Europe to the global inventory of the stable isotopic composition of methane
- Author
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Menoud, Malika, primary, van der Veen, Carina, additional, Lowry, Dave, additional, Fernandez, Julianne M., additional, Bakkaloglu, Semra, additional, France, James L., additional, Fisher, Rebecca E., additional, Maazallahi, Hossein, additional, Stanisavljević, Mila, additional, Nęcki, Jarosław, additional, Vinkovic, Katarina, additional, Łakomiec, Patryk, additional, Rinne, Janne, additional, Korbeń, Piotr, additional, Schmidt, Martina, additional, Defratyka, Sara, additional, Yver-Kwok, Camille, additional, Andersen, Truls, additional, Chen, Huilin, additional, and Röckmann, Thomas, additional
- Published
- 2022
- Full Text
- View/download PDF
25. Spatial and temporal variation in δ13C values of methane emitted from a hemiboreal mire: methanogenesis, methanotrophy, and hysteresis
- Author
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Rinne, Janne, primary, Łakomiec, Patryk, additional, Vestin, Patrik, additional, White, Joel D., additional, Weslien, Per, additional, Kelly, Julia, additional, Kljun, Natascha, additional, Ström, Lena, additional, and Klemedtsson, Leif, additional
- Published
- 2022
- Full Text
- View/download PDF
26. Optimising the CH4 simulations from the LPJ-GUESS model using Adaptive MCMC
- Author
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Theanutti Kallingal Jalisha, Scholze Marko, A. Miller Paul, Lindstrom Johan, Rinne Janne, and Raivonen Maarit
- Subjects
AMCMC ,Data assimilation ,Siikaneva ,Methane ,LPJ-GUESS - Abstract
CH4 simulations from the LPJ-GUESS, a process-based dynamic global vegetation model,was calibrated using the daily CH4 flux observations collected at Siikaneva wetlands ( Finland)from 2005 to 2014.Rao-Blackwellised modification ofAdaptive Metropolis MCMC sampling algorithm was used to calibrate the model. The code, data used to input the model and the data used to optimise the model are uploaded.
- Published
- 2022
- Full Text
- View/download PDF
27. Spatial and temporal variation in δ13C values of methane emitted from a hemiboreal mire: methanogenesis, methanotrophy, and hysteresis
- Author
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Rinne, Janne, Łakomiec, Patryk, Vestin, Patrik, White, Joel D., Weslien, Per, Kelly, Julia, Kljun, Natascha, Ström, Lena, and Klemedtsson, Leif
- Abstract
The reasons for spatial and temporal variation in methane emission from mire ecosystems are not fully understood. Stable isotope signatures of the emitted methane can offer clues to the causes of these variations. We measured the methane emission (FCH4) and 13C signature (δ13C) of emitted methane by automated chambers at a hemiboreal mire for two growing seasons. In addition, we used ambient methane mixing ratios and δ13C to calculate a mire-scale 13C signature using a nocturnal boundary-layer accumulation approach. Microbial methanogenic and methanotrophic communities were determined by a captured metagenomics analysis. The chamber measurements showed large and systematic spatial variations in δ13C-CH4 of up to 15 ‰ but smaller and less systematic temporal variation. According to the spatial δ13C–FCH4 relations, methanotrophy was unlikely to be the dominating cause for the spatial variation. Instead, these were an indication of the substrate availability of methanogenesis being a major factor in explaining the spatial variation. Genetic analysis indicated that methanogenic communities at all sample locations were able to utilize both hydrogenotrophic and acetoclastic pathways and could thus adapt to changes in the available substrate. The temporal variation in FCH4 and δ13C over the growing seasons showed hysteresis-like behavior at high-emission locations, indicative of time-lagged responses to temperature and substrate availability. The upscaled chamber measurements and nocturnal boundary-layer accumulation measurements showed similar average δ13C values of −81.3 ‰ and −79.3 ‰, respectively, indicative of hydrogenotrophic methanogenesis at the mire. The close correspondence of the δ13C values obtained by the two methods lends confidence to the obtained mire-scale isotopic signature. This and other recently published data on δ13C values of CH4 emitted from northern mires are considerably lower than the values used in atmospheric inversion studies on methane sources, suggesting a need for revision of the model input.
- Published
- 2022
28. Optimising CH4 simulations from the LPJ-GUESS model v4.1 using an adaptive MCMC algorithm.
- Author
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Kallingal, Jalisha T., Lindström, Johan, Miller, Paul A., Rinne, Janne, Raivonen, Maarit, and Scholze, Marko
- Subjects
MARKOV chain Monte Carlo ,SALT marshes ,ALGORITHMS - Abstract
The processes responsible for methane (CH
4 ) emissions from boreal wetlands are complex, and hence their model representation is complicated by a large number of parameters and parameter uncertainties. The arctic-enabled dynamic global vegetation model LPJ-GUESS is one such model that allows quantification and understanding of the natural wetland CH4 fluxes at various scales ranging from local to regional and global, but with several uncertainties. The model contains detailed descriptions of CH4 production, oxidation, and transport controlled by several process parameters. Complexities in the underlying environmental processes, warming-driven alternative paths of meteorological phenomena, and changes in hydrological and vegetation conditions are highlight the need for a calibrated and optimised version of LPJGUESS. In this study we formulated the parameter calibration as a Bayesian problem, using knowledge of reasonable parameters values as priors. We then used an adaptive Metropolis Hastings (MH) based Markov Chain Monte Carlo (MCMC) algorithm to improve predictions of CH4 emission by LPJ-GUESS and to quantify uncertainties. Application of this method on uncertain parameters allows greater search of their posterior distribution, leading to a more complete characterisation of the posterior distribution with reduced risk of sample impoverishment that can occur when using other optimisation methods. For assimilation, the analysis used flux measurement data gathered during the period 2005 to 2014 from the Siikaneva wetlands in southern Finland with an estimation of measurement uncertainties. The data are used to constrain the processes behind the CH4 dynamics, and the posterior covariance structures are used to explain how the parameters and the processes are related. To further support the conclusions, the CH4 flux and the other component fluxes associated with the flux are examined. The results demonstrate the robustness of MCMC methods to quantitatively assess the interrelationship between objective function choices, parameter identifiability, and data support. As a part of this work, knowledge about how the CH4 data can constrain the parameters and processes is derived. Though the optimisation is performed based on a single site's flux data from Siikaneva, the algorithm is useful for larger-scale multi-site studies for more robust calibration of LPJ-GUESS and similar models, and the results can highlight where model improvements are needed. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
29. High-resolution spatial patterns and drivers of terrestrial ecosystem carbon dioxide, methane, and nitrous oxide fluxes in the tundra.
- Author
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Virkkala, Anna-Maria, Niittynen, Pekka, Kemppinen, Julia, Marushchak, Maija E., Voigt, Carolina, Hensgens, Geert, Kerttula, Johanna, Happonen, Konsta, Tyystjärvi, Vilna, Biasi, Christina, Hultman, Jenni, Rinne, Janne, and Luoto, Miska
- Subjects
TUNDRAS ,CARBON dioxide ,NITROUS oxide ,GROWING season ,SOIL moisture ,PLANT biomass - Abstract
Arctic terrestrial greenhouse gas (GHG) fluxes of carbon dioxide (CO
2 ), methane (CH4 ) and nitrous oxide (N2 O) play an important role in the global GHG budget. However, these GHG fluxes are rarely studied simultaneously, and our understanding of the conditions controlling them across spatial gradients is limited. Here, we explore the magnitudes and drivers of GHG fluxes across fine-scale terrestrial gradients during the peak growing season (July) in sub-Arctic Finland. We measured chamber-derived GHG fluxes and soil temperature, soil moisture, soil organic carbon and nitrogen stocks, soil pH, soil carbon-to-nitrogen (C/N) ratio, soil dissolved organic carbon content, vascular plant biomass, and vegetation type from 101 plots scattered across a heterogeneous tundra landscape (5 km²). We used these field data together with high-resolution remote sensing data to develop machine learning models to predict (i.e., upscale) daytime GHG fluxes across the landscape at 2-m resolution. Our results show that this region was on average a daytime net GHG sink during the growing season. Although our results suggest that this sink was driven by CO2 uptake, it also revealed small but widespread CH4 uptake in upland vegetation types, shifting this region to an average net CH4 sink at the landscape scale during growing season, despite the presence of high-emitting wetlands. Average N2 O fluxes were negligible. CO2 fluxes were controlled primarily by annual average soil temperature and biomass (both increase net sink) and vegetation type, CH4 fluxes by soil moisture (increases net emissions) and vegetation type, and N2 O fluxes by soil C/N (lower C/N increases net source). These results demonstrate the potential of high spatial resolution modelling of GHG fluxes in the Arctic. They also reveal the dominant role of CO2 fluxes across the tundra landscape, but suggest that CH4 uptake might play a significant role in the regional GHG budget. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
30. Assessing CO2 and CH4 fluxes from mounds of African fungus-growing termites.
- Author
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Räsänen, Matti, Vesala, Risto, Rönnholm, Petri, Arppe, Laura, Manninen, Petra, Jylhä, Markus, Rikkinen, Jouko, Pellikka, Petri, and Rinne, Janne
- Subjects
TERMITES ,SAVANNAS ,SOIL respiration ,HETEROTROPHIC respiration ,BIRD nests - Abstract
Termites play an essential role in decomposing dead plant material in tropical ecosystems and are thus major sources of gaseous C emissions in many environments. In African savannas, fungus-growing termites are among the ecologically most influential termite species. We studied the gas exchange from mounds of two closely related fungus-growing species (Macrotermes subhyalinus and M. michaelseni, respectively) in shaded and open habitats together with soil fluxes around the mounds. The fluxes from active termite mounds varied from 116 to 2105 mg CO
2 -C m-2 h-1 for CO2 and from 0.06 to 3.66 mg CH4 -C m-2 h-1 for CH4 fluxes. Mound CO2 fluxes varied seasonally with a 64 % decrease and 35 % increase in the fluxes from dry to wet season at the open grassland and shaded bushland sites, respectively. During the wet season, the CO2 fluxes were significantly correlated with termite mound volume. The diurnal measurements from two M. michaelseni mounds suggest that the gas fluxes peak during daytime and midnight supporting the previously presented model of thermally driven air circulation inside the mound and possibly enhanced ventilation during the night by the opening of foraging routes. The stability of the mound gas fluxes over diurnal and annual scales coincides with the constant nature of the nest internal gas and thermal environment that guarantees continuously favorable conditions for the fungal symbiont. Soil fluxes of both CO2 and CH4 were enhanced at up to 2 m distance from the mounds compared to the local soil respiration, indicating that, in addition to mound ventilation structures, a small proportion of the produced metabolic gases leave the nest also via surrounding soils. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
31. Tropical and Boreal Forest Atmosphere Interactions : A Review
- Author
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Artaxo, Paulo, Hansson, Hans-Christen, Andreae, Meinrat O., Bäck, Jaana, Alves, Eliane Gomes, Barbosa, Henrique M. J., Bender, Frida, Bourtsoukidis, Efstratios, Carbone, Samara, Chi, Jinshu, Decesari, Stefano, Despres, Viviane R., Ditas, Florian, Ezhova, Ekaterina, Fuzzi, Sandro, Hasselquist, Niles J., Heintzenberg, Jost, Holanda, Bruna A., Guenther, Alex, Hakola, Hannele, Heikkinen, Liine, Kerminen, Veli-Matti, Kontkanen, Jenni, Krejci, Radovan, Kulmala, Markku, Lavric, Jost, de Leeuw, Gerrit, Lehtipalo, Katrianne, Machado, Luiz Augusto T., McFiggans, Gordon, Franco, Marco Aurelio M., Meller, Bruno Backes, Morais, Fernando G., Mohr, Claudia, Morgan, William, Nilsson, Mats B., Peichl, Matthias, Petäjä, Tuukka, Prass, Maria, Poehlker, Christopher, Poehlker, Mira L., Poeschl, Ulrich, Von Randow, Celso, Riipinen, Ilona, Rinne, Janne, Rizzo, Luciana, Rosenfeld, Daniel, Silva Dias, Maria A. F., Sogacheva, Larisa, Stier, Philip, Swietlicki, Erik, Soergel, Matthias, Tunved, Peter, Virkkula, Aki, Wang, Jian, Weber, Bettina, Maria Yanez-Serrano, Ana, Zieger, Paul, Mikhailov, Eugene, Smith, James N., Kesselmeier, Juergen, Viikki Plant Science Centre (ViPS), Department of Forest Sciences, Forest Ecology and Management, Ecosystem processes (INAR Forest Sciences), Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, Global Atmosphere-Earth surface feedbacks, Department of Physics, and Air quality research group
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biomass burning ,4112 Forestry ,Tropical forests ,aerosol particles ,LONG-TERM MEASUREMENTS ,LAND-USE CHANGE ,NUCLEATION-MODE PARTICLES ,PRIMARY BIOLOGICAL AEROSOL ,TOWER OBSERVATORY ZOTTO ,114 Physical sciences ,AMAZON RAIN-FOREST ,CLOUD CONDENSATION NUCLEI ,Boreal forests ,Amazonia ,SECONDARY ORGANIC AEROSOL ,BIOMASS BURNING AEROSOLS ,INTERTROPICAL CONVERGENCE ZONE ,biogenic emissions: fires ,climate effects - Abstract
This review presents how the boreal and the tropical forests affect the atmosphere, its chemical composition, its function, and further how that affects the climate and, in return, the ecosystems through feedback processes. Observations from key tower sites standing out due to their long-term comprehensive observations: The Amazon Tall Tower Observatory in Central Amazonia, the Zotino Tall Tower Observatory in Siberia, and the Station to Measure Ecosystem-Atmosphere Relations at Hyytiala in Finland. The review is complemented by short-term observations from networks and large experiments. The review discusses atmospheric chemistry observations, aerosol formation and processing, physiochemical aerosol, and cloud condensation nuclei properties and finds surprising similarities and important differences in the two ecosystems. The aerosol concentrations and chemistry are similar, particularly concerning the main chemical components, both dominated by an organic fraction, while the boreal ecosystem has generally higher concentrations of inorganics, due to higher influence of long-range transported air pollution. The emissions of biogenic volatile organic compounds are dominated by isoprene and monoterpene in the tropical and boreal regions, respectively, being the main precursors of the organic aerosol fraction. Observations and modeling studies show that climate change and deforestation affect the ecosystems such that the carbon and hydrological cycles in Amazonia are changing to carbon neutrality and affect precipitation downwind. In Africa, the tropical forests are so far maintaining their carbon sink. It is urgent to better understand the interaction between these major ecosystems, the atmosphere, and climate, which calls for more observation sites, providing long-term data on water, carbon, and other biogeochemical cycles. This is essential in finding a sustainable balance between forest preservation and reforestation versus a potential increase in food production and biofuels, which are critical in maintaining ecosystem services and global climate stability. Reducing global warming and deforestation is vital for tropical forests.
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- 2022
32. Spatial and temporal variation of 13C signature of methane emitted from a temperate mire: Methanogenesis, methanotrophy, and hysteresis
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Rinne, Janne, Łakomiec, Patryk, Vestin, Patrik, White, Joel D., Weslien, Per, Kelly, Julia, Kljun, Natascha, Ström, Lena, and Klemedtsson, Leif
- Abstract
The reasons for spatial and temporal variation of methane emission from mire ecosystems are not fully understood. Stable isotope signatures of the emitted methane can offer cues to the causes of these variations. We measured the methane emission and 13C-signature of emitted methane by automated chambers at a temperate mire for two growing seasons. In addition, we used ambient methane mixing ratios and δ13C-CH4 to calculate a mire-scale 13C signature using a nocturnal boundary-layer accumulation approach. Microbial methanogenic and methanotrophic communities were determined by a captured metagenomics analysis. The chamber measurements showed large and systematic spatial variations in δ13C-CH4 of up to 15 ‰ but smaller and less systematic temporal variation. The trophic status of methanogenesis was the dominant factor explaining the spatial variation. Genetic analysis indicated that methanogenic communities at all sample locations were able to utilize both hydrogenotrophic and acetoclastic pathways and could thus adapt to trophic status. The temporal variation of methane emission and δ13C-CH4 over the growing seasons showed hysteresis-like behavior, indicative of time-lagged responses to temperature and trophic status. The up-scaled chamber measurements and nocturnal boundary-layer accumulation measurements showed similar average δ13C-CH4 values of -81.3 ‰ and -79.3 ‰, respectively, lending confidence to the use of mire scale isotopic signatures to be used in e.g. atmospheric inversion modelling of methane sources. The results obtained can constrain our theories on the variability of methane emission from mire ecosystems and be useful in development of numerical models of mire biogeochemistry.
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- 2022
33. Reply on RC2
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Rinne, Janne, primary
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- 2022
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34. Strong isoprene emission response to temperature in tundra vegetation
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Seco, Roger, primary, Holst, Thomas, additional, Davie-Martin, Cleo L., additional, Simin, Tihomir, additional, Guenther, Alex, additional, Pirk, Norbert, additional, Rinne, Janne, additional, and Rinnan, Riikka, additional
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- 2022
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35. Tropical and Boreal Forest – Atmosphere Interactions: A Review
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Artaxo, Paulo, primary, Hansson, Hans-Christen, additional, Andreae, Meinrat O., additional, Bäck, Jaana, additional, Alves, Eliane Gomes, additional, Barbosa, Henrique M. J., additional, Bender, Frida, additional, Bourtsoukidis, Efstratios, additional, Carbone, Samara, additional, Chi, Jinshu, additional, Decesari, Stefano, additional, Després, Viviane R., additional, Ditas, Florian, additional, Ezhova, Ekaterina, additional, Fuzzi, Sandro, additional, Hasselquist, Niles J., additional, Heintzenberg, Jost, additional, Holanda, Bruna A., additional, Guenther, Alex, additional, Hakola, Hannele, additional, Heikkinen, Liine, additional, Kerminen, Veli-Matti, additional, Kontkanen, Jenni, additional, Krejci, Radovan, additional, Kulmala, Markku, additional, Lavric, Jost V., additional, De Leeuw, Gerrit, additional, Lehtipalo, Katrianne, additional, Machado, Luiz Augusto T., additional, McFiggans, Gordon, additional, Franco, Marco Aurelio M., additional, Meller, Bruno Backes, additional, Morais, Fernando G., additional, Mohr, Claudia, additional, Morgan, William, additional, Nilsson, Mats B., additional, Peichl, Matthias, additional, Petäjä, Tuukka, additional, Praß, Maria, additional, Pöhlker, Christopher, additional, Pöhlker, Mira L., additional, Pöschl, Ulrich, additional, Von Randow, Celso, additional, Riipinen, Ilona, additional, Rinne, Janne, additional, Rizzo, Luciana V., additional, Rosenfeld, Daniel, additional, Silva Dias, Maria A. F., additional, Sogacheva, Larisa, additional, Stier, Philip, additional, Swietlicki, Erik, additional, Sörgel, Matthias, additional, Tunved, Peter, additional, Virkkula, Aki, additional, Wang, Jian, additional, Weber, Bettina, additional, Yáñez-Serrano, Ana Maria, additional, Zieger, Paul, additional, Mikhailov, Eugene, additional, Smith, James N., additional, and Kesselmeier, Jürgen, additional
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- 2022
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36. Supplementary material to "Spatial and temporal variation of <sup>13</sup>C signature of methane emitted from a temperate mire: Methanogenesis, methanotrophy, and hysteresis"
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Rinne, Janne, primary, Łakomiec, Patryk, additional, Vestin, Patrik, additional, White, Joel D., additional, Weslien, Per, additional, Kelly, Julia, additional, Kljun, Natascha, additional, Ström, Lena, additional, and Klemedtsson, Leif, additional
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- 2022
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37. Spatial and temporal variation of <sup>13</sup>C signature of methane emitted from a temperate mire: Methanogenesis, methanotrophy, and hysteresis
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Rinne, Janne, primary, Łakomiec, Patryk, additional, Vestin, Patrik, additional, White, Joel D., additional, Weslien, Per, additional, Kelly, Julia, additional, Kljun, Natascha, additional, Ström, Lena, additional, and Klemedtsson, Leif, additional
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- 2022
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38. The Integrated Carbon Observation System in Europe
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Heiskanen, Jouni, primary, Brümmer, Christian, additional, Buchmann, Nina, additional, Calfapietra, Carlo, additional, Chen, Huilin, additional, Gielen, Bert, additional, Gkritzalis, Thanos, additional, Hammer, Samuel, additional, Hartman, Susan, additional, Herbst, Mathias, additional, Janssens, Ivan A., additional, Jordan, Armin, additional, Juurola, Eija, additional, Karstens, Ute, additional, Kasurinen, Ville, additional, Kruijt, Bart, additional, Lankreijer, Harry, additional, Levin, Ingeborg, additional, Linderson, Maj-Lena, additional, Loustau, Denis, additional, Merbold, Lutz, additional, Myhre, Cathrine Lund, additional, Papale, Dario, additional, Pavelka, Marian, additional, Pilegaard, Kim, additional, Ramonet, Michel, additional, Rebmann, Corinna, additional, Rinne, Janne, additional, Rivier, Léonard, additional, Saltikoff, Elena, additional, Sanders, Richard, additional, Steinbacher, Martin, additional, Steinhoff, Tobias, additional, Watson, Andrew, additional, Vermeulen, Alex T., additional, Vesala, Timo, additional, Vítková, Gabriela, additional, and Kutsch, Werner, additional
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- 2022
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39. Effects of livestock and wildlife grazing intensity on soil carbon dioxide flux in the savanna grassland of Kenya
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Wachiye, Sheila, primary, Pellikka, Petri, additional, Rinne, Janne, additional, Heiskanen, Janne, additional, Abwanda, Sheila, additional, and Merbold, Lutz, additional
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- 2022
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40. Global inventory of the stable isotopic composition of methane surface emissions, augmented by new measurements in Europe
- Author
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Menoud, Malika, primary, van der Veen, Carina, additional, Lowry, Dave, additional, Fernandez, Julianne M., additional, Bakkaloglu, Semra, additional, France, James L., additional, Fisher, Rebecca E., additional, Maazallahi, Hossein, additional, Stanisavljević, Mila, additional, Nęcki, Jarosław, additional, Vinkovic, Katarina, additional, Łakomiec, Patryk, additional, Rinne, Janne, additional, Korbeń, Piotr, additional, Schmidt, Martina, additional, Defratyka, Sara, additional, Yver-Kwok, Camille, additional, Andersen, Truls, additional, Chen, Huilin, additional, and Röckmann, Thomas, additional
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- 2022
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41. Genetic functional potential displays minor importance in explaining spatial variability of methane fluxes within a Eriophorum vaginatum dominated Swedish peatland
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White, Joel Dawson, primary, Ström, Lena, additional, Lehsten, Veiko, additional, Rinne, Janne, additional, and Ahrén, Dag, additional
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- 2022
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42. Field-scale CH<sub>4</sub> emission at a subarctic mire with heterogeneous permafrost thaw status
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Łakomiec, Patryk, primary, Holst, Jutta, additional, Friborg, Thomas, additional, Crill, Patrick, additional, Rakos, Niklas, additional, Kljun, Natascha, additional, Olsson, Per-Ola, additional, Eklundh, Lars, additional, Persson, Andreas, additional, and Rinne, Janne, additional
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- 2021
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43. Vertical distribution of sources and sinks of VOCs within a boreal forest canopy.
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Petersen, Ross Charles, Holst, Thomas, Mölder, Meelis, Kljun, Natascha, and Rinne, Janne
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AEROSOLS ,AIR quality ,CLIMATOLOGY ,METHANOL ,ACETONE - Abstract
The ecosystem-atmosphere flux of biogenic volatile organic compounds (BVOCs) has important impacts on tropospheric oxidative capacity and the formation of secondary organic aerosols, influencing air quality and climate. Here we present within-canopy measurements of a set of dominant BVOCs in a managed spruce- and pine-dominated boreal forest located at the ICOS station Norunda in Sweden, collected using proton transfer reaction mass spectrometry (PTR-MS) during 2014–2016, and vertical emission profiles derived from these data. Ozone concentrations were simultaneously measured in conjunction with these PTR-MS measurements. The main BVOCs investigated with the PTR-MS were isoprene, monoterpenes, methanol, acetaldehyde, and acetone. The distribution of BVOC sources and sinks in the forest canopy was explored using Lagrangian dispersion matrix methods, in particular continuous near-field theory. The forest canopy was found to contribute ca. 86 % to the total monoterpene emission in summertime, whereas the below-canopy and canopy emission was comparable (ca. 42 % and 58 % respectively) during the autumn period. This result indicates that boreal forest litter and other below-canopy emitters are a principle source for total forest monoterpene emissions during autumn months. During night, our results for methanol, acetone, and acetaldehyde seasonally present strong sinks in the forest canopy, especially in the autumn, likely due to the nighttime formation of dew on vegetation surfaces. [ABSTRACT FROM AUTHOR]
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- 2022
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44. Supplementary material to "The effect of rainfall amount and timing on annual transpiration in a grazed savanna grassland"
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Räsänen, Matti, primary, Aurela, Mika, additional, Vakkari, Ville, additional, Beukes, Johan P., additional, Tuovinen, Juha-Pekka, additional, Van Zyl, Pieter G., additional, Josipovic, Miroslav, additional, Siebert, Stefan J., additional, Laurila, Tuomas, additional, Kulmala, Markku, additional, Laakso, Lauri, additional, Rinne, Janne, additional, Oren, Ram, additional, and Katul, Gabriel, additional
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- 2021
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45. The effect of rainfall amount and timing on annual transpiration in a grazed savanna grassland
- Author
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Räsänen, Matti, primary, Aurela, Mika, additional, Vakkari, Ville, additional, Beukes, Johan P., additional, Tuovinen, Juha-Pekka, additional, Van Zyl, Pieter G., additional, Josipovic, Miroslav, additional, Siebert, Stefan J., additional, Laurila, Tuomas, additional, Kulmala, Markku, additional, Laakso, Lauri, additional, Rinne, Janne, additional, Oren, Ram, additional, and Katul, Gabriel, additional
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- 2021
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46. Spatial and temporal variation of 13C signature of methane emitted from a temperate mire: Methanogenesis, methanotrophy, and hysteresis.
- Author
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Rinne, Janne, Łakomiec, Patryk, Vestin, Patrik, White, Joel D., Weslien, Per, Kelly, Julia, Kljun, Natascha, Ström, Lena, and Klemedtsson, Leif
- Subjects
SPATIAL variation ,METHANE ,ISOTOPIC signatures ,STABLE isotopes ,GROWING season ,HYSTERESIS - Abstract
The reasons for spatial and temporal variation of methane emission from mire ecosystems are not fully understood. Stable isotope signatures of the emitted methane can offer cues to the causes of these variations. We measured the methane emission and
13 C-signature of emitted methane by automated chambers at a temperate mire for two growing seasons. In addition, we used ambient methane mixing ratios and δ13 C-CH4 to calculate a mire-scale13 C signature using a nocturnal boundary-layer accumulation approach. Microbial methanogenic and methanotrophic communities were determined by a captured metagenomics analysis. The chamber measurements showed large and systematic spatial variations in δ13 C-CH4 of up to 15 ‰ but smaller and less systematic temporal variation. The trophic status of methanogenesis was the dominant factor explaining the spatial variation. Genetic analysis indicated that methanogenic communities at all sample locations were able to utilize both hydrogenotrophic and acetoclastic pathways and could thus adapt to trophic status. The temporal variation of methane emission and δ13 C-CH4 over the growing seasons showed hysteresis-like behavior, indicative of time-lagged responses to temperature and trophic status. The up-scaled chamber measurements and nocturnal boundary-layer accumulation measurements showed similar average δ13 C-CH4 values of -81.3 ‰ and -79.3 ‰, respectively, lending confidence to the use of mire scale isotopic signatures to be used in e.g. atmospheric inversion modelling of methane sources. The results obtained can constrain our theories on the variability of methane emission from mire ecosystems and be useful in development of numerical models of mire biogeochemistry. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
47. Global inventory of the stable isotopic composition of methane surface emissions, augmented by new measurements in Europe.
- Author
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Menoud, Malika, der Veen, Carina van, Lowry, Dave, Fernandez, Julianne M., Bakkaloglu, Semra, France, James L., Fisher, Rebecca E., Maazallahi, Hossein, Stanisavljević, Mila, Nęcki, Jarosław, Vinkovic, Katarina, Łakomiec, Patryk, Rinne, Janne, Korbeń, Piotr, Schmidt, Martina, Defratyka, Sara, Yver-Kwok, Camille, Andersen, Truls, Huilin Chen, and Röckmann, Thomas
- Subjects
EMISSION inventories ,CLIMATE change mitigation ,ISOTOPIC signatures ,METHANE ,FOSSIL fuels ,INVENTORIES ,AUTOMOBILE emissions - Abstract
Recent climate change mitigation strategies rely on the reduction of methane (CH
4 ) emissions. δ13 CCH 4 and δ²HCH 4 measurements can be used to distinguish sources and thus to understand the CH4 budget better. The CH4 emission estimates by models are sensitive to the isotopic signatures assigned to each source category, so it is important to provide representative estimates of the different CH4 source isotopic signatures worldwide. We present new measurements of isotope signatures of various, mainly anthropogenic, CH4 sources in Europe, which represent a substantial contribution to the global dataset of source isotopic measurements from the literature, especially for δ²HCH 4 . They improve the definition of δ13 CCH 4 from waste sources, and demonstrate the use of δ²HCH 4 for fossil fuel source attribution. Results from previous studies were combined in a common database that we updated with our new measurements, as well as with additional literature. We found that microbial sources are generally well characterised. The large variability in fossil fuels isotopic compositions requires particular care in the choice of weighting criteria for the calculation of a representative global value. The global dataset could be further improved by measurements from African, South American and Asian countries, as well as more measurements from pyrogenic sources. The final version of the European methane isotope database coupled with a global inventory of fossil and non-fossil δ13 CCH 4 and δ²HCH 4 source signature measurements, is available at: https://doi.org/10.24416/UU01-4PO56T (Menoud et al., 2021a). [ABSTRACT FROM AUTHOR]- Published
- 2022
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- View/download PDF
48. Genetic functional potential displays minor importance in explaining spatial variability of methane fluxes within a Eriophorum vaginatum dominated Swedish peatland.
- Author
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White, Joel D., Ström, Lena, Lehsten, Veiko, Rinne, Janne, and Ahrén, Dag
- Subjects
BIOENGINEERING ,GEOCHEMISTRY ,EARTH system science ,BIOCHEMISTRY ,MICROBIOLOGY ,TUNDRAS ,METHANE ,GEOGRAPHY - Abstract
Microbial communities of methane (CH
4 ) producing methanogens and consuming methanotrophs play an important role for Earth's atmospheric CH4 budget. Despite their global significance, knowledge on how much they control the spatial variation in CH4 fluxes from peatlands is poorly understood. We studied variation in CH4 producing and consuming communities in a natural peatland dominated by Eriophorum vaginatum, via a metagenomics approach using custom designed hybridization-based oligonucleotide probes to focus on taxa and functions associated with methane cycling. We hypothesized that sites with different magnitudes of methane flux are occupied by structurally and functionally different microbial communities, despite the dominance of a single vascular plant species. To investigate this, nine plant-peat mesocosms dominated by the sedge Eriophorum vaginatum, with varying vegetation coverage, were collected from a temperate natural wetland and subjected to a simulated growing season. During the simulated growing season, measurements of CH4 emission, carbon dioxide (CO2 ) exchange and δ13 C signature of emitted CH4 were made. Mesocosms 1 through 9 were classified into three categories according to the magnitude of CH4 flux. Gross primary production and ecosystem respiration followed the same pattern as CH4 fluxes, but this trend was not observed in net ecosystem exchange. We observed that genetic functional potential was of minor importance in explaining spatial variability of CH4 fluxes with only small shifts in taxonomic community and functional genes. In addition, a higher β-diversity was observed in samples with high CH4 emission. Among methanogens, Methanoregula, made up over 50% of the community composition. This, in combination with the remaining hydrogenotrophic methanogens matched the δ13 C isotopic signature of emitted CH4 . However, the presence of acetoclastic and methylotrophic taxa and type I, II and Verrucomicrobia methanotrophs indicates that the microbial community holds the ability to produce and consume CH4 in multiple ways. This is important in terms of future climate scenarios, where peatlands are expected to alter in nutrient status, hydrology, and peat biochemistry. Due to the high functional potential, we expect the community to be highly adaptive to future climate scenarios. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
49. The effect of rainfall amount and timing on annual transpiration in a grazed savanna grassland.
- Author
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Rasanen, Matti, Aurela, Mika, Vakkari, Ville, Beukes, Johan P., Tuovinen, Juha-Pekka, Zyl, Pieter G. Van, Josipovic, Miroslav, Siebert, Stefan J., Laurila, Tuomas, Kulmala, Markku, Laakso, Lauri, Rinne, Janne, Oren, Ram, and Katul, Gabriel
- Abstract
The role of precipitation (P) variability on evapotranspiration (ET) and its two components, transpiration (T) and evaporation (E) from savannas, continues to draw significant research interest given its relevance to a number of eco-hydrological applications. Our study reports on six years of measured ET and estimated T and E from a grazed savanna grassland in Welgegund, South Africa. Annual P varied significantly in amount (508 to 672 mm yr
-1 ), with dry years characterized by infrequent early-season rainfall. T was determined using annual water-use efficiency and gross primary production estimates derived from eddy covariance measurements of latent heat flux and net ecosystem CO2 exchange rates. The computed annual T was nearly constant, 331 ± 11 mm yr-1 (T/ET=0.52), for the four wet years with frequent early wet-season rainfall, whereas annual T was 268 and 175 mm yr-1 during the dry years. Annual T/ET was linearly related to the early wet-season storm frequency. The constancy of annual T during wet years is explained by the moderate water stress of C4 grass and constant annual tree transpiration covering 15% of the landscape. However, grass transpiration declines during dry spells. Moreover, grasses respond to water availability with a dieback-regrowth pattern, reducing leaf area and transpiration during drought. These changes lead to an anomalous monthly T/ET relation to leaf-area index (LAI). The results highlight the role of the C4 grass layer in the hydrological balance and suggest that the grass response to dry spells and drought is reasonably described by precipitation timing. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
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50. Soil Greenhouse Gas Emissions from Dominant Land Use Types in Lowlands and Highlands of Southern Kenya
- Author
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Sheila Wachiye, University of Helsinki, Faculty of Science, Doctoral Programme in Atmospheric Sciences, Helsingin yliopisto, matemaattis-luonnontieteellinen tiedekunta, Ilmakehätieteiden tohtoriohjelma, Helsingfors universitet, matematisk-naturvetenskapliga fakulteten, Doktorandprogrammet i atmosfärvetenskap, Skiba, Ute Maria, Pellikka, Petri, Merbold, Lutz, and Rinne, Janne
- Subjects
geosciences and Geography - Abstract
Land-use changes account for three-quarters of Africa's anthropogenic greenhouse gas (GHG) emissions, yet little is known about these emissions from a wide variety of land uses, especially from the savanna in Sub-Saharan Africa. To address this gap, I conducted four studies (2018 - 2021) to quantify soil GHG emissions from dominant land use types (LUTs) in the Taita Taveta county, southern Kenya. Three studies were carried out in the lowland under savanna grassland (private conservation and community grazing), bushland, maize cropland (Zea mays L.), and sisal plantation. The fourth study was in the highlands under indigenous forest, pine and eucalyptus plantations, woodland, and maize cropland. Each study covered a whole year. Soil GHG concentrations were measured with static GHG chambers and analysed by gas chromatography over eight one-week and weekly campaigns. Environmental factors including soil temperature, volumetric soil moisture content, vegetation, soil physicochemical characteristics and grazing intensity were evaluated. Daily CO2 emissions varied between 5 – 360 mg C m-2 h-1 and differed between sites. In the lowland, grassland under conservation land had the highest CO2 emissions, while cropland and bushland had the lowest. In the highlands, the pine plantation and indigenous forest emitted higher CO2 than eucalyptus and woodland, while cropland emitted the least. Overall, soil organic carbon accounted for 50% variation in CO2 emissions between the LUTs, while grazing accounted for 60% variation between grassland under conservation and the community grazing. In the sisal plantation, the oldest and youngest stands emitted higher CO2 than mature stands, which is consistent with root respiration since soil organic carbon did not differ between stands. During each study year, CO2 emissions were highest in the wet than in the dry season due to the higher soil moisture and vegetation cover. In the lowland, soil moisture alone explained 20 – 70% seasonal variation in CO2 emissions, while vegetation (based on EVI and NDVI; proxies of vegetation status) explained 18 – 82%. The combined influence of soil moisture and vegetation dynamics proved to be a greater control accounting for 75 – 96% of seasonal variation in CO2 emissions. The indigenous forest and pine plantation were affected by soil temperature rather than moisture, but the relationship was very weak (< 20%). In the lowland, soil N2O (-7.7 – 17 µg N m- 2 h-1) and CH4 (-0.4 – 1.9 mg C m-2 h-1) emissions were very low throughout each study period. Most CH4 values were below the limit of detection (LOD; ±0.03 mg C m-2 h-1) and the ones above were sinks rather than sources, and they did not differ between seasons or sites. N2O emissions were highest in cropland and lowest in bushland but did not vary with season. In the maize cropland, manure application was very low and had no effect on N2O emissions. Due to low soil carbon, nitrogen, and moisture content at all LUTs, N2O and CH4 emissions were of minor significance. Among the assessed LUTs, soil carbon content, moisture, and vegetation characteristics were key drivers for soil GHG emissions. The findings of this study address a significant gap in the spatial and temporal variability of soil GHG emissions in Sub-Saharan Africa, which can be used to improve current estimates, thereby improving climate change mitigation measures when identifying and quantifying national contributions. In Africa, land-use changes account for three-quarters of anthropogenic greenhouse gas (GHG: carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4)) emissions. However, few studies have measured these emissions, especially in Sub-Saharan Africa's savanna, where land use changes are accelerating due to population growth. I conducted four studies to quantify soil GHG emissions from dominant land use types (LUTs) in southern Kenya's Taita Taveta county under varying management. Three studies were carried out in the lowland under savanna grassland (private conservation lands, community grazing lands), bushland, maize cropland (Zea mays L.), and sisal plantation, while the fourth in the highlands under indigenous forest, pine and eucalyptus plantations, and woodland, and adjacent maize cropland. Each study covered the whole year. Soil GHG concentrations were measured with static GHG chambers and analysed by gas chromatography. Environmental factors including soil temperature, volumetric soil moisture content, vegetation, soil physicochemical characteristics and grazing intensity were evaluated. Overall, conservation land, which is privately managed, had the highest CO2 emissions in the lowland due to dense grass cover, while cropland and bushland had the lowest. In the highlands, the pine plantation and indigenous forest with higher soil organic carbon emitted higher CO2 than eucalyptus and woodland, while cropland emitted the lowest. Soil organic carbon explained 50% of the variation in CO2 emissions between the studied LUTs, while grazing accounted for 60% difference between grassland under conservation and community grazing. In sisal plantations, the effect of stand age on GHG emissions was studied. It was found that old and young sisal stands emitted more CO2 than mature stands due to higher root respiration which increases with stand age. Harvesting and weeding interfered with root respiration in the mature stands. CO2 emissions were greater in the wet season than in the dry season due to higher soil moisture and vegetation cover. In the lowland, soil moisture explained 20 - 70% of the seasonal variation in CO2 emissions, while vegetation cover explained 18 - 82%. Combined soil moisture and vegetation dynamics accounted for 75-96% of the variation in seasonal CO2 emissions. Indigenous forests and pine plantations were affected by soil temperature more than moisture, but this relationship was very weak (< 20%), probably due to the narrow seasonal variations in soil temperature. N2O and CH4 were very low throughout each study period in the lowland. For CH4, most values were below the limit of detection, and the ones above were sinks rather than sources. Seasons and sites did not affect CH4 values. N2O emissions were highest in cropland and lowest in bushland, but they did not vary by season. Manure application in the maize cropland was very low and had no impact on N2O emissions. Overall, N2O and CH4 emissions were of minor significance at all sites due to the low soil carbon, nitrogen, and moisture conditions. In this way, this study fills a critically important gap in our understanding of soil GHG emissions in sub-Saharan Africa and contributes to better estimates of baseline GHG emissions in Africa, both of which are crucial for reducing uncertainties in global GHG budgets and for informing policymakers when discussing low-emission development strategies.
- Published
- 2022
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