The Experts below are selected from a list of 7635 Experts worldwide ranked by ideXlab platform
Sven Jonasson - One of the best experts on this subject based on the ideXlab platform.
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Ecosystem Respiration depends strongly on photosynthesis in a temperate heath
Biogeochemistry, 2007Co-Authors: Klaus Steenberg Larsen, Sven Jonasson, Andreas Ibrom, Claus Beier, Anders MichelsenAbstract:We measured net Ecosystem CO2 flux (F n) and Ecosystem Respiration (R E), and estimated gross Ecosystem photosynthesis (P g) by difference, for two years in a temperate heath Ecosystem using a chamber method. The exchange rates of carbon were high and of similar magnitude as for productive forest Ecosystems with a net Ecosystem carbon gain during the second year of 293 ± 11 g C m−2 year−1 showing that the carbon sink strength of heather-dominated Ecosystems may be considerable when C. vulgaris is in the building phase of its life cycle. The estimated gross Ecosystem photosynthesis and Ecosystem Respiration from October to March was 22% and 30% of annual flux, respectively, suggesting that both cold-season carbon gain and loss were important in the annual carbon cycle of the Ecosystem. Model fit of R E of a classic, first-order exponential equation related to temperature (second year; R 2 = 0.65) was improved when the P g rate was incorporated into the model (second year; R 2 = 0.79), suggesting that daytime R E increased with increasing photosynthesis. Furthermore, the temperature sensitivity of R E decreased from apparent Q 10 values of 3.3 to 3.9 by the classic equation to a more realistic Q 10 of 2.5 by the modified model. The model introduces R photo, which describes the part of Respiration being tightly coupled to the photosynthetic rate. It makes up 5% of the assimilated carbon dioxide flux at 0°C and 35% at 20°C implying a high sensitivity of Respiration to photosynthesis during summer. The simple model provides an easily applied, non-intrusive tool for investigating seasonal trends in the relationship between Ecosystem carbon sequestration and Respiration.
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temperature and substrate controls on intra annual variation in Ecosystem Respiration in two subarctic vegetation types
Global Change Biology, 2005Co-Authors: Paul Grogan, Sven JonassonAbstract:Arctic Ecosystems are important in the context of climate change because they are expected to undergo the most rapid temperature increases, and could provide a globally significant release of CO2 to the atmosphere from their extensive bulk soil organic carbon reserves. Understanding the relative contributions of bulk soil organic matter and plant-associated carbon pools to Ecosystem Respiration is critical to predicting the response of arctic Ecosystem net carbon balance to climate change. In this study, we determined the variation in Ecosystem Respiration rates from birch forest understory and heath tundra vegetation types in northern Sweden through a full annual cycle. We used a plant biomass removal treatment to differentiate bulk soil organic matter Respiration from total Ecosystem Respiration in each vegetation type. Plant-associated and bulk soil organic matter carbon pools each contributed significantly to Ecosystem Respiration during most phases of winter and summer in the two vegetation types. Ecosystem Respiration rates through the year did not differ significantly between vegetation types despite substantial differences in biomass pools, soil depth and temperature regime. Most (76‐92%) of the intra-annual variation in Ecosystem Respiration rates from these two common mesic subarctic Ecosystems was explained using a first-order exponential equation relating Respiration to substrate chemical quality and soil temperature. Removal of plants and their current year’s litter significantly reduced the sensitivity of Ecosystem Respiration to intra-annual variations in soil temperature for both vegetation types, indicating that Respiration derived from recent plant carbon fixation was more temperature sensitive than Respiration from bulk soil organic matter carbon stores. Accurate assessment of the potential for positive feedbacks from high-latitude Ecosystems to CO2-induced climate change will require the development of Ecosystemlevel physiological models of net carbon exchange that differentiate the responses of major C pools, that account for effects of vegetation type, and that integrate over summer and winter seasons.
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Temperature and substrate controls on intra‐annual variation in Ecosystem Respiration in two subarctic vegetation types
Global Change Biology, 2005Co-Authors: Paul Grogan, Sven JonassonAbstract:Arctic Ecosystems are important in the context of climate change because they are expected to undergo the most rapid temperature increases, and could provide a globally significant release of CO2 to the atmosphere from their extensive bulk soil organic carbon reserves. Understanding the relative contributions of bulk soil organic matter and plant-associated carbon pools to Ecosystem Respiration is critical to predicting the response of arctic Ecosystem net carbon balance to climate change. In this study, we determined the variation in Ecosystem Respiration rates from birch forest understory and heath tundra vegetation types in northern Sweden through a full annual cycle. We used a plant biomass removal treatment to differentiate bulk soil organic matter Respiration from total Ecosystem Respiration in each vegetation type. Plant-associated and bulk soil organic matter carbon pools each contributed significantly to Ecosystem Respiration during most phases of winter and summer in the two vegetation types. Ecosystem Respiration rates through the year did not differ significantly between vegetation types despite substantial differences in biomass pools, soil depth and temperature regime. Most (76‐92%) of the intra-annual variation in Ecosystem Respiration rates from these two common mesic subarctic Ecosystems was explained using a first-order exponential equation relating Respiration to substrate chemical quality and soil temperature. Removal of plants and their current year’s litter significantly reduced the sensitivity of Ecosystem Respiration to intra-annual variations in soil temperature for both vegetation types, indicating that Respiration derived from recent plant carbon fixation was more temperature sensitive than Respiration from bulk soil organic matter carbon stores. Accurate assessment of the potential for positive feedbacks from high-latitude Ecosystems to CO2-induced climate change will require the development of Ecosystemlevel physiological models of net carbon exchange that differentiate the responses of major C pools, that account for effects of vegetation type, and that integrate over summer and winter seasons.
Jay P. Zarnetske - One of the best experts on this subject based on the ideXlab platform.
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Quantification of metabolically active transient storage (MATS) in two reaches with contrasting transient storage and Ecosystem Respiration
Journal of Geophysical Research, 2011Co-Authors: Alba Argerich, Roy Haggerty, Eugenia Marti, Francesc Sabater, Jay P. ZarnetskeAbstract:This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/jgr/.Water transient storage zones are hotspots for metabolic activity in streams although the contribution of different types of transient storage zones to the whole-reach metabolic activity is difficult to quantify. In this study we present a method to measure the fraction of the transient storage that is metabolically active (MATS) in two consecutive reaches with contrasting hydrological and biological characteristics. We used combined additions of resazurin (Raz) and Cl in a reach scoured to bedrock and in a reach containing a deep alluvial deposit. The MATS zones measured 0.002 m² in the bedrock reach (37% of transient storage) and 0.291 m² in the alluvial reach (100% of transient storage). The effective rate coefficient of Raz transformation in the MATS of the bedrock reach was approximately 16 times that of the alluvial reach. However, when we take into account the contribution of the MATS zone to overall metabolic activity, Raz transformation in the MATS zone was 2.2 times slower in the bedrock reach than in the alluvial reach. The difference was similar to the difference in Ecosystem Respiration, which was 1.8 times lower in the bedrock reach than in the alluvial reach, suggesting that the MATS zones were important contributors to Ecosystem Respiration. Results indicate that the quantification of MATS can improve our understanding of the role that transient storage zones play on stream metabolic processes and demonstrate the utility of Raz as a “smart” tracer that provides new information on metabolic activity at a whole-reach and at smaller scale
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Quantification of metabolically active transient storage (MATS) in two reaches with contrasting transient storage and Ecosystem Respiration
Journal of Geophysical Research, 2011Co-Authors: Alba Argerich, Roy Haggerty, Eugenia Marti, Francesc Sabater, Jay P. ZarnetskeAbstract:a deep alluvial deposit. The MATS zones measured 0.002 m 2 in the bedrock reach (37% of transient storage) and 0.291 m 2 in the alluvial reach (100% of transient storage). The effective rate coefficient of Raz transformation in the MATS of the bedrock reach was approximately 16 times that of the alluvial reach. However, when we take into account the contribution of the MATS zone to overall metabolic activity, Raz transformation in the MATS zone was 2.2 times slower in the bedrock reach than in the alluvial reach. The difference was similar to the difference in Ecosystem Respiration, which was 1.8 times lower in the bedrock reach than in the alluvial reach, suggesting that the MATS zones were important contributors to Ecosystem Respiration. Results indicate that the quantification of MATS can improve our understanding of the role that transient storage zones play on stream metabolic processes and demonstrate the utility of Raz as a “smart” tracer that provides new information on metabolic activity at a whole‐reach and at smaller scale. Citation: Argerich, A., R. Haggerty, E. Marti, F. Sabater, and J. Zarnetske (2011), Quantification of metabolically active transient storage (MATS) in two reaches with contrasting transient storage and Ecosystem Respiration, J. Geophys. Res., 116, G03034, doi:10.1029/2010JG001379.
Alba Argerich - One of the best experts on this subject based on the ideXlab platform.
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Ecosystem Respiration increases with biofilm growth and bed forms flume measurements with resazurin
Journal of Geophysical Research, 2014Co-Authors: Roy Haggerty, Miquel Ribot, Gabriel Singer, Eugenia Marti, Alba Argerich, Gemma Agell, Tom J BattinAbstract:In a set of streamside mesocosms, stream Ecosystem Respiration (ER) increased with biofilm biomass and flow heterogeneity (turbulence) generated by impermeable bed forms, even though those bed forms had no hyporheic exchange. Two streamside flumes with gravel beds (single layer of gravel) were operated in parallel. The first flume had no bed forms, and the second flume had 10 cm high dune-shaped bed forms with a wavelength of 1.0 m. Ecosystem Respiration was measured via resazurin reduction to resorufin in each flume at three different biomass stages during biofilm growth. Results support the hypothesis that ER increases with flow heterogeneity generated by bed forms across all biofilm biomass stages. For the same biofilm biomass, ER was up to 1.9 times larger for a flume with 10 cm high impermeable bed forms than for a flume without the bed forms. Further, the amount of increase in ER associated with impermeable bed forms was itself increased as biofilms grew. Regardless of bed forms, biofilms increased transient storage by a factor of approximately 4.
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Quantification of metabolically active transient storage (MATS) in two reaches with contrasting transient storage and Ecosystem Respiration
Journal of Geophysical Research, 2011Co-Authors: Alba Argerich, Roy Haggerty, Eugenia Marti, Francesc Sabater, Jay P. ZarnetskeAbstract:This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/jgr/.Water transient storage zones are hotspots for metabolic activity in streams although the contribution of different types of transient storage zones to the whole-reach metabolic activity is difficult to quantify. In this study we present a method to measure the fraction of the transient storage that is metabolically active (MATS) in two consecutive reaches with contrasting hydrological and biological characteristics. We used combined additions of resazurin (Raz) and Cl in a reach scoured to bedrock and in a reach containing a deep alluvial deposit. The MATS zones measured 0.002 m² in the bedrock reach (37% of transient storage) and 0.291 m² in the alluvial reach (100% of transient storage). The effective rate coefficient of Raz transformation in the MATS of the bedrock reach was approximately 16 times that of the alluvial reach. However, when we take into account the contribution of the MATS zone to overall metabolic activity, Raz transformation in the MATS zone was 2.2 times slower in the bedrock reach than in the alluvial reach. The difference was similar to the difference in Ecosystem Respiration, which was 1.8 times lower in the bedrock reach than in the alluvial reach, suggesting that the MATS zones were important contributors to Ecosystem Respiration. Results indicate that the quantification of MATS can improve our understanding of the role that transient storage zones play on stream metabolic processes and demonstrate the utility of Raz as a “smart” tracer that provides new information on metabolic activity at a whole-reach and at smaller scale
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Quantification of metabolically active transient storage (MATS) in two reaches with contrasting transient storage and Ecosystem Respiration
Journal of Geophysical Research, 2011Co-Authors: Alba Argerich, Roy Haggerty, Eugenia Marti, Francesc Sabater, Jay P. ZarnetskeAbstract:a deep alluvial deposit. The MATS zones measured 0.002 m 2 in the bedrock reach (37% of transient storage) and 0.291 m 2 in the alluvial reach (100% of transient storage). The effective rate coefficient of Raz transformation in the MATS of the bedrock reach was approximately 16 times that of the alluvial reach. However, when we take into account the contribution of the MATS zone to overall metabolic activity, Raz transformation in the MATS zone was 2.2 times slower in the bedrock reach than in the alluvial reach. The difference was similar to the difference in Ecosystem Respiration, which was 1.8 times lower in the bedrock reach than in the alluvial reach, suggesting that the MATS zones were important contributors to Ecosystem Respiration. Results indicate that the quantification of MATS can improve our understanding of the role that transient storage zones play on stream metabolic processes and demonstrate the utility of Raz as a “smart” tracer that provides new information on metabolic activity at a whole‐reach and at smaller scale. Citation: Argerich, A., R. Haggerty, E. Marti, F. Sabater, and J. Zarnetske (2011), Quantification of metabolically active transient storage (MATS) in two reaches with contrasting transient storage and Ecosystem Respiration, J. Geophys. Res., 116, G03034, doi:10.1029/2010JG001379.
Paul Grogan - One of the best experts on this subject based on the ideXlab platform.
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temperature and substrate controls on intra annual variation in Ecosystem Respiration in two subarctic vegetation types
Global Change Biology, 2005Co-Authors: Paul Grogan, Sven JonassonAbstract:Arctic Ecosystems are important in the context of climate change because they are expected to undergo the most rapid temperature increases, and could provide a globally significant release of CO2 to the atmosphere from their extensive bulk soil organic carbon reserves. Understanding the relative contributions of bulk soil organic matter and plant-associated carbon pools to Ecosystem Respiration is critical to predicting the response of arctic Ecosystem net carbon balance to climate change. In this study, we determined the variation in Ecosystem Respiration rates from birch forest understory and heath tundra vegetation types in northern Sweden through a full annual cycle. We used a plant biomass removal treatment to differentiate bulk soil organic matter Respiration from total Ecosystem Respiration in each vegetation type. Plant-associated and bulk soil organic matter carbon pools each contributed significantly to Ecosystem Respiration during most phases of winter and summer in the two vegetation types. Ecosystem Respiration rates through the year did not differ significantly between vegetation types despite substantial differences in biomass pools, soil depth and temperature regime. Most (76‐92%) of the intra-annual variation in Ecosystem Respiration rates from these two common mesic subarctic Ecosystems was explained using a first-order exponential equation relating Respiration to substrate chemical quality and soil temperature. Removal of plants and their current year’s litter significantly reduced the sensitivity of Ecosystem Respiration to intra-annual variations in soil temperature for both vegetation types, indicating that Respiration derived from recent plant carbon fixation was more temperature sensitive than Respiration from bulk soil organic matter carbon stores. Accurate assessment of the potential for positive feedbacks from high-latitude Ecosystems to CO2-induced climate change will require the development of Ecosystemlevel physiological models of net carbon exchange that differentiate the responses of major C pools, that account for effects of vegetation type, and that integrate over summer and winter seasons.
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Temperature and substrate controls on intra‐annual variation in Ecosystem Respiration in two subarctic vegetation types
Global Change Biology, 2005Co-Authors: Paul Grogan, Sven JonassonAbstract:Arctic Ecosystems are important in the context of climate change because they are expected to undergo the most rapid temperature increases, and could provide a globally significant release of CO2 to the atmosphere from their extensive bulk soil organic carbon reserves. Understanding the relative contributions of bulk soil organic matter and plant-associated carbon pools to Ecosystem Respiration is critical to predicting the response of arctic Ecosystem net carbon balance to climate change. In this study, we determined the variation in Ecosystem Respiration rates from birch forest understory and heath tundra vegetation types in northern Sweden through a full annual cycle. We used a plant biomass removal treatment to differentiate bulk soil organic matter Respiration from total Ecosystem Respiration in each vegetation type. Plant-associated and bulk soil organic matter carbon pools each contributed significantly to Ecosystem Respiration during most phases of winter and summer in the two vegetation types. Ecosystem Respiration rates through the year did not differ significantly between vegetation types despite substantial differences in biomass pools, soil depth and temperature regime. Most (76‐92%) of the intra-annual variation in Ecosystem Respiration rates from these two common mesic subarctic Ecosystems was explained using a first-order exponential equation relating Respiration to substrate chemical quality and soil temperature. Removal of plants and their current year’s litter significantly reduced the sensitivity of Ecosystem Respiration to intra-annual variations in soil temperature for both vegetation types, indicating that Respiration derived from recent plant carbon fixation was more temperature sensitive than Respiration from bulk soil organic matter carbon stores. Accurate assessment of the potential for positive feedbacks from high-latitude Ecosystems to CO2-induced climate change will require the development of Ecosystemlevel physiological models of net carbon exchange that differentiate the responses of major C pools, that account for effects of vegetation type, and that integrate over summer and winter seasons.
Roy Haggerty - One of the best experts on this subject based on the ideXlab platform.
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Ecosystem Respiration increases with biofilm growth and bed forms flume measurements with resazurin
Journal of Geophysical Research, 2014Co-Authors: Roy Haggerty, Miquel Ribot, Gabriel Singer, Eugenia Marti, Alba Argerich, Gemma Agell, Tom J BattinAbstract:In a set of streamside mesocosms, stream Ecosystem Respiration (ER) increased with biofilm biomass and flow heterogeneity (turbulence) generated by impermeable bed forms, even though those bed forms had no hyporheic exchange. Two streamside flumes with gravel beds (single layer of gravel) were operated in parallel. The first flume had no bed forms, and the second flume had 10 cm high dune-shaped bed forms with a wavelength of 1.0 m. Ecosystem Respiration was measured via resazurin reduction to resorufin in each flume at three different biomass stages during biofilm growth. Results support the hypothesis that ER increases with flow heterogeneity generated by bed forms across all biofilm biomass stages. For the same biofilm biomass, ER was up to 1.9 times larger for a flume with 10 cm high impermeable bed forms than for a flume without the bed forms. Further, the amount of increase in ER associated with impermeable bed forms was itself increased as biofilms grew. Regardless of bed forms, biofilms increased transient storage by a factor of approximately 4.
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Quantification of metabolically active transient storage (MATS) in two reaches with contrasting transient storage and Ecosystem Respiration
Journal of Geophysical Research, 2011Co-Authors: Alba Argerich, Roy Haggerty, Eugenia Marti, Francesc Sabater, Jay P. ZarnetskeAbstract:This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/jgr/.Water transient storage zones are hotspots for metabolic activity in streams although the contribution of different types of transient storage zones to the whole-reach metabolic activity is difficult to quantify. In this study we present a method to measure the fraction of the transient storage that is metabolically active (MATS) in two consecutive reaches with contrasting hydrological and biological characteristics. We used combined additions of resazurin (Raz) and Cl in a reach scoured to bedrock and in a reach containing a deep alluvial deposit. The MATS zones measured 0.002 m² in the bedrock reach (37% of transient storage) and 0.291 m² in the alluvial reach (100% of transient storage). The effective rate coefficient of Raz transformation in the MATS of the bedrock reach was approximately 16 times that of the alluvial reach. However, when we take into account the contribution of the MATS zone to overall metabolic activity, Raz transformation in the MATS zone was 2.2 times slower in the bedrock reach than in the alluvial reach. The difference was similar to the difference in Ecosystem Respiration, which was 1.8 times lower in the bedrock reach than in the alluvial reach, suggesting that the MATS zones were important contributors to Ecosystem Respiration. Results indicate that the quantification of MATS can improve our understanding of the role that transient storage zones play on stream metabolic processes and demonstrate the utility of Raz as a “smart” tracer that provides new information on metabolic activity at a whole-reach and at smaller scale
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Quantification of metabolically active transient storage (MATS) in two reaches with contrasting transient storage and Ecosystem Respiration
Journal of Geophysical Research, 2011Co-Authors: Alba Argerich, Roy Haggerty, Eugenia Marti, Francesc Sabater, Jay P. ZarnetskeAbstract:a deep alluvial deposit. The MATS zones measured 0.002 m 2 in the bedrock reach (37% of transient storage) and 0.291 m 2 in the alluvial reach (100% of transient storage). The effective rate coefficient of Raz transformation in the MATS of the bedrock reach was approximately 16 times that of the alluvial reach. However, when we take into account the contribution of the MATS zone to overall metabolic activity, Raz transformation in the MATS zone was 2.2 times slower in the bedrock reach than in the alluvial reach. The difference was similar to the difference in Ecosystem Respiration, which was 1.8 times lower in the bedrock reach than in the alluvial reach, suggesting that the MATS zones were important contributors to Ecosystem Respiration. Results indicate that the quantification of MATS can improve our understanding of the role that transient storage zones play on stream metabolic processes and demonstrate the utility of Raz as a “smart” tracer that provides new information on metabolic activity at a whole‐reach and at smaller scale. Citation: Argerich, A., R. Haggerty, E. Marti, F. Sabater, and J. Zarnetske (2011), Quantification of metabolically active transient storage (MATS) in two reaches with contrasting transient storage and Ecosystem Respiration, J. Geophys. Res., 116, G03034, doi:10.1029/2010JG001379.
