scholarly journals Cushion bog plant community responses to passive warming in southern Patagonia

2021 ◽  
Vol 18 (16) ◽  
pp. 4817-4839
Author(s):  
Verónica Pancotto ◽  
David Holl ◽  
Julio Escobar ◽  
María Florencia Castagnani ◽  
Lars Kutzbach
Keyword(s):  
Carbon Dioxide ◽  
Plant Community ◽  
Plant Traits ◽  
Ecosystem Respiration ◽  
Vascular Plant ◽  
Carbon Dioxide Flux ◽  
Tierra Del Fuego ◽  
Near Surface ◽  
Passive Warming ◽  
Southern Patagonia

Abstract. Vascular plant-dominated cushion bogs, which are exclusive to the Southern Hemisphere, are highly productive and constitute large sinks for atmospheric carbon dioxide compared to their moss-dominated counterparts around the globe. In this study, we experimentally investigated how a cushion bog plant community responded to elevated surface temperature conditions as they are predicted to occur in a future climate. We conducted the study in a cushion bog dominated by Astelia pumila on Tierra del Fuego, Argentina. We installed a year-round passive warming experiment using semicircular plastic walls that raised average near-surface air temperatures by between 0.4 and 0.7 ∘C (at the 3 of the 10 treatment plots which were equipped with temperature sensors). We focused on characterizing differences in morphological cushion plant traits and in carbon dioxide exchange dynamics using chamber gas flux measurements. We used a mechanistic modeling approach to quantify physiological plant traits and to partition the net carbon dioxide flux into its two components of photosynthesis and total ecosystem respiration. We found that A. pumila reduced its photosynthetic activity under elevated temperatures. At the same time, we observed enhanced respiration which we largely attribute, due to the limited effect of our passive warming on soil temperatures, to an increase in autotrophic respiration. Passively warmed A. pumila cushions sequestered between 55 % and 85 % less carbon dioxide than untreated control cushions over the main growing season. Our results suggest that even moderate future warming under the SSP1-2.6 scenario could decrease the carbon sink function of austral cushion bogs.

scholarly journals Cushion bog plant community responses to passive warming in southern Patagonia

2020 ◽  
Author(s):  
Verónica Pancotto ◽  
David Holl ◽  
Julio Escobar ◽  
María Florencia Castagnani ◽  
Lars Kutzbach
Keyword(s):  
Carbon Dioxide ◽  
Plant Community ◽  
Plant Traits ◽  
Ecosystem Respiration ◽  
Vascular Plant ◽  
Carbon Dioxide Flux ◽  
Tierra Del Fuego ◽  
Near Surface ◽  
Passive Warming ◽  
Southern Patagonia

Abstract. Vascular plant-dominated cushion bogs, which are exclusive to the southern hemisphere, are highly productive and constitute large sinks for atmospheric carbon dioxide compared to their moss-dominated counterparts around the globe. In this study, we experimentally investigated how a cushion bog plant community responded to elevated surface temperature conditions as they are predicted to occur in a future climate. We conducted the study in a cushion bog dominated by Astelia pumila on Tierra del Fuego, Argentina. We installed a year-round passive warming experiment using semicircular plastic walls that raised average near-surface air temperatures between 0.4 °C and 0.7 °C (n = 3). We focused on characterizing differences in morphological cushion plant traits and in carbon dioxide exchange dynamics using chamber gas flux measurements. We used a mechanistic modeling approach to quantify physiological plant traits and to partition the net carbon dioxide flux into its two components photosynthesis and total ecosystem respiration. We found that A. pumila reduced its photosynthetic activity under elevated temperatures. At the same time, we observed enhanced respiration which we largely attribute, due to the limited effect of our passive warming on soil temperatures, to an increase in autotrophic respiration. Passively warmed A. pumila cushions sequestered between 55 % and 85 % less carbon dioxide than untreated control cushions over the main growing season. These results suggest that future warming could decrease the carbon sink function of austral cushion bogs.

scholarly journals Cushion bogs are stronger carbon dioxide net sinks than moss-dominated bogs as revealed by eddy covariance measurements on Tierra del Fuego, Argentina

2019 ◽  
Vol 16 (17) ◽  
pp. 3397-3423 ◽  
Author(s):  
David Holl ◽  
Verónica Pancotto ◽  
Adrian Heger ◽  
Sergio Jose Camargo ◽  
Lars Kutzbach
Keyword(s):  
Carbon Dioxide ◽  
Eddy Covariance ◽  
Ecosystem Respiration ◽  
Vascular Plant ◽  
Tierra Del Fuego ◽  
Peat Moss ◽  
High Temporal Resolution ◽  
Sink Strength ◽  
Bog Ecosystems ◽  
Annual Nee

Abstract. The near-pristine bog ecosystems of Tierra del Fuego in southernmost Patagonia have so far not been studied in terms of their current carbon dioxide (CO2) sink strength. CO2 flux data from Southern Hemisphere peatlands are scarce in general. In this study, we present CO2 net ecosystem exchange (NEE) fluxes from two Fuegian bog ecosystems with contrasting vegetation communities. One site is located in a glaciogenic valley and developed as a peat moss-dominated raised bog, and the other site is a vascular plant-dominated cushion bog located at the coast of the Beagle Channel. We measured NEE fluxes with two identical eddy covariance (EC) setups at both sites for more than 2 years. With the EC method, we were able to observe NEE fluxes on an ecosystem level and at high temporal resolution. Using a mechanistic modeling approach, we estimated daily NEE models to gap fill and partition the half-hourly net CO2 fluxes into components related to photosynthetic uptake (gross primary production, GPP) and to total ecosystem respiration (TER). We found a larger relative variability of annual NEE sums between both years at the moss-dominated site. A warm and dry first year led to comparably high TER sums. Photosynthesis was also promoted by warmer conditions but less strongly than TER with respect to absolute and relative GPP changes. The annual NEE carbon (C) uptake was more than 3 times smaller in the warm year. Close to the sea at the cushion bog site, the mean temperature difference between both observed years was less pronounced, and TER stayed on similar levels. A higher amount of available radiation in the second observed year led to an increase in GPP (5 %) and NEE (35 %) C uptake. The average annual NEE-C uptake of the cushion bog (-122±76 gm-2a-1, n=2) was more than 4 times larger than the average uptake of the moss-dominated bog (-27±28 gm-2a-1, n=2).

scholarly journals Cushion bogs are stronger carbon dioxide net sinks than moss-dominated bogs as revealed by eddy covariance measurements on Tierra del Fuego, Argentina

2019 ◽  
Author(s):  
David Holl ◽  
Verónica Pancotto ◽  
Adrian Heger ◽  
Sergio Jose Camargo ◽  
Lars Kutzbach
Keyword(s):  
Carbon Dioxide ◽  
Eddy Covariance ◽  
Ecosystem Respiration ◽  
Vascular Plant ◽  
Tierra Del Fuego ◽  
Peat Moss ◽  
High Temporal Resolution ◽  
Sink Strength ◽  
Bog Ecosystems ◽  
Annual Nee

Abstract. The near-pristine bog ecosystems of Tierra del Fuego in southernmost Patagonia have so far not been studied in terms of their current carbon dioxide (CO2) sink strength. CO2 flux data from southern hemisphere peatlands is scarce in general. In this study, we present CO2 net ecosystem exchange (NEE) fluxes from two Fuegian bog ecosystems with contrasting vegetation communities. One site is located in a glaciogenic valley and developed as a peat moss-dominated raised bog, the other site is a vascular plant-dominated cushion bog located at the coast of the Beagle Channel. We measured NEE fluxes with two identical eddy covariance (EC) setups at both sites for more than two years. With the EC method, we were able to observe NEE fluxes on ecosystem level and at high temporal resolution. Using a mechanistic modeling approach, we estimated daily NEE models to gap-fill and partition the half-hourly net CO2 fluxes into components related to photosynthetic uptake (gross primary production, GPP) and to total ecosystem respiration (TER). We found a larger relative variability of annual NEE sums between both years at the moss-dominated site. A warm and dry first year led to comparably high TER sums. Photosynthesis was also promoted by warmer conditions but less strong than TER with respect to absolute and relative GPP changes. The annual NEE-C uptake was more than three times smaller in the warm year. Close to the sea at the cushion bog site, the mean temperature difference between both observed years was less pronounced, and TER stayed on similar levels. A higher amount of available radiation in the second observed year led to an increase of GPP (5 %) and NEE (35 %) carbon (C) uptake. The average annual NEE-C uptake of the cushion bog (−122 ± 76 g m−2 a−1, n = 2) was more than four times larger than the average uptake of the moss-dominated bog (−27 ± 28 g m−2 a−1, n = 2).

scholarly journals Supplementary material to "Cushion bog plant community responses to passive warming in southern Patagonia"

2020 ◽  
Author(s):  
Verónica Pancotto ◽  
David Holl ◽  
Julio Escobar ◽  
María Florencia Castagnani ◽  
Lars Kutzbach
Keyword(s):  
Plant Community ◽  
Community Responses ◽  
Passive Warming ◽  
Southern Patagonia ◽  
Supplementary Material

scholarly journals Carbon dioxide and methane exchange of a patterned subarctic fen during two contrasting growing seasons

2020 ◽  
Author(s):  
Lauri Heiskanen ◽  
Juha-Pekka Tuovinen ◽  
Aleksi Räsänen ◽  
Tarmo Virtanen ◽  
Sari Juutinen ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Plant Community ◽  
Ecosystem Respiration ◽  
Growing Season ◽  
Vegetation Composition ◽  
Flux Chamber ◽  
Growing Seasons ◽  
Community Types ◽  
Eddy Covariance Measurements ◽  
Carbon Dioxide Co2

Abstract. The patterned microtopography of subarctic mires generates a variety of environmental conditions, and carbon dioxide (CO2) and methane (CH4) dynamics vary spatially among different plant community types. We studied the CO2 and CH4 exchange between a subarctic fen and the atmosphere at Kaamanen in northern Finland based on flux chamber and eddy covariance measurements in 2017–2018. We observed strong spatial variation in carbon dynamics between the four main plant community types (PCTs) studied, which were largely controlled by water table level and differences in vegetation composition. The ecosystem respiration (ER) and gross primary productivity (GPP) increased gradually from the wettest PCT to the drier ones, and both ER and GPP were larger for all PCTs during the warmer and drier growing season 2018. We estimated that in 2017 the growing season CO2 balances of the PCTs ranged from −20 g C m−2 (Trichophorum tussock PCT) to 64 g C m−2 (string margin PCT), while in 2018 all PCTs were small CO2 sources (10–22 g C m−2). We observed small growing season CH4 emission sums (

scholarly journals Seasonal variation in ecosystem parameters derived from FLUXNET data

2009 ◽  
Vol 6 (2) ◽  
pp. 2863-2912 ◽  
Author(s):  
M. Groenendijk ◽  
M. K. van der Molen ◽  
A. J. Dolman
Keyword(s):  
Carbon Dioxide ◽  
Seasonal Variation ◽  
Ecosystem Respiration ◽  
Vegetation Type ◽  
Correlation Coefficients ◽  
Carbon Dioxide Flux ◽  
Model Parameters ◽  
Flux Data ◽  
Quality Checks ◽  
Parameter Values

Abstract. The carbon dioxide sink is in a complex way related to weather and climate. In order to better understand the relationship and feedbacks, we present a methodology to simulate observed carbon dioxide flux data with a simple vegetation model (5PM) with weekly varying model parameters. The model parameters explain the interaction between vegetation and seasonal climate more general than the flux data. Two parameters (Rref and E0) are related to ecosystem respiration and three parameters (Jm, α and λ) to photosynthesis and transpiration. We quantified the weekly variability of ecosystem parameters as a function of vegetation type and climate region. After statistical quality checks 121 FLUXNET sites were available for analysis of the weekly varying model parameters. The simulations of these sites have high correlation coefficients (r2=0.6 to 0.8) between the observed and simulated carbon and water fluxes. With weekly parameters we determined average seasonal cycles for the different combinations of vegetation type and climate regions (PFTs). The variation between PFTs is large, which provides an excellent dataset to study the differences in ecosystem characteristics. In general we observed that needleleaf forests and grasslands in warmer climates have relatively constant parameter values during the year. Broadleaf forests in all climate regions have large seasonal variation for each of the five parameters. In boreal regions parameter values are always lower than in temperate regions. A large seasonality of the model parameters indicates a strong relation between vegetation and climate. This suggests that climate change will have the largest impact on the terrestrial carbon fluxes in boreal regions and for deciduous forests, and less for grasslands and evergreen forests.

scholarly journals Quantifying the UK’s Carbon Dioxide Flux: An atmospheric inverse modelling approach using a regional measurement network

2018 ◽  
Author(s):  
Emily D. White ◽  
Matthew Rigby ◽  
Mark F. Lunt ◽  
Anita L. Ganesan ◽  
Alistair J. Manning ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Primary Productivity ◽  
Net Primary Productivity ◽  
Transport Model ◽  
Ecosystem Respiration ◽  
Carbon Dioxide Flux ◽  
Inverse Modelling ◽  
Chemical Transport Model ◽  
The Uk ◽  
The Impact

Abstract. We present a method to derive atmospheric-observation-based estimates of carbon dioxide (CO2) fluxes at the national scale, demonstrated using data from a network of surface tall tower sites across the UK and Ireland over the period 2013–2014. The inversion is carried out using simulations from a Lagrangian chemical transport model and an innovative hierarchical Bayesian Markov chain Monte Carlo (MCMC) framework, which addresses some of the traditional problems faced by inverse modelling studies, such as subjectivity in the specification of model and prior uncertainties. Biospheric fluxes related to gross primary productivity and terrestrial ecosystem respiration are solved separately in the inversion and then combined a posteriori to determine net primary productivity. Two different models, CARDAMOM and JULES, provide prior estimates for these fluxes. We carry out separate inversions to assess the impact of these different priors on the posterior flux estimates and evaluate the differences between the prior and posterior estimates in terms of missing model components. The Numerical Atmospheric dispersion Modelling Environment (NAME) is used to relate fluxes to the measurements taken across the regional network. Posterior CO2 estimates from the two inversions agree within estimated uncertainties, despite large differences in the prior fluxes from the different models. With our method, averaging results from 2013 and 2014, we find a total annual net biospheric flux for the UK of −8 ± 79 Tg CO2 yr−1 (CARDAMOM prior) and −64 ± 85 Tg CO2 yr−1 (JULES prior), where -ve values represent an uptake of CO2. These biospheric CO2 estimates show that annual UK biospheric sources and sinks are roughly in balance. These annual mean estimates are consistently higher than the prior estimates, which show much more pronounced uptake in the summer months.

scholarly journals Quantifying the UK's carbon dioxide flux: an atmospheric inverse modelling approach using a regional measurement network

2019 ◽  
Vol 19 (7) ◽  
pp. 4345-4365 ◽  
Author(s):  
Emily D. White ◽  
Matthew Rigby ◽  
Mark F. Lunt ◽  
T. Luke Smallman ◽  
Edward Comyn-Platt ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Transport Model ◽  
Ecosystem Respiration ◽  
Atmospheric Dispersion ◽  
Terrestrial Ecosystem ◽  
Carbon Dioxide Flux ◽  
Inverse Modelling ◽  
Chemical Transport Model ◽  
The Uk ◽  
The Impact

Abstract. We present a method to derive atmospheric-observation-based estimates of carbon dioxide (CO2) fluxes at the national scale, demonstrated using data from a network of surface tall-tower sites across the UK and Ireland over the period 2013–2014. The inversion is carried out using simulations from a Lagrangian chemical transport model and an innovative hierarchical Bayesian Markov chain Monte Carlo (MCMC) framework, which addresses some of the traditional problems faced by inverse modelling studies, such as subjectivity in the specification of model and prior uncertainties. Biospheric fluxes related to gross primary productivity and terrestrial ecosystem respiration are solved separately in the inversion and then combined a posteriori to determine net ecosystem exchange of CO2. Two different models, Data Assimilation Linked Ecosystem Carbon (DALEC) and Joint UK Land Environment Simulator (JULES), provide prior estimates for these fluxes. We carry out separate inversions to assess the impact of these different priors on the posterior flux estimates and evaluate the differences between the prior and posterior estimates in terms of missing model components. The Numerical Atmospheric dispersion Modelling Environment (NAME) is used to relate fluxes to the measurements taken across the regional network. Posterior CO2 estimates from the two inversions agree within estimated uncertainties, despite large differences in the prior fluxes from the different models. With our method, averaging results from 2013 and 2014, we find a total annual net biospheric flux for the UK of 8±79 Tg CO2 yr−1 (DALEC prior) and 64±85 Tg CO2 yr−1 (JULES prior), where negative values represent an uptake of CO2. These biospheric CO2 estimates show that annual UK biospheric sources and sinks are roughly in balance. These annual mean estimates consistently indicate a greater net release of CO2 than the prior estimates, which show much more pronounced uptake in summer months.

Initial carbon dynamics of perennial grassland conversion for annual cropping in Manitoba

2013 ◽  
Vol 93 (3) ◽  
pp. 379-391 ◽  
Author(s):  
Trevor J. Fraser ◽  
Brian D. Amiro
Keyword(s):  
Carbon Dioxide ◽  
Ecosystem Respiration ◽  
Perennial Grass ◽  
Carbon Dynamics ◽  
Carbon Dioxide Flux ◽  
Control Field ◽  
Initial Carbon ◽  
Grassland Conversion ◽  
Perennial Grassland ◽  
Atmospheric Carbon

Fraser, T. J. and Amiro, B. D. 2013. Initial carbon dynamics of perennial grassland conversion for annual cropping in Manitoba. Can. J. Soil Sci. 93: 379–391. Sequestering atmospheric carbon in agricultural soil is an attractive option for mitigation of rising atmospheric carbon dioxide concentrations. Perennial crops are more likely to gain carbon whereas annual crops are more likely to lose carbon. A pair of eddy covariance towers were set up near Winnipeg Manitoba, Canada, to measure the carbon dioxide flux over adjacent paired perennial grass hay fields with high soil organic carbon. A Treatment field was converted to annual cropping by spraying with herbicide, cutting and tilling. A Control field was cut, but allowed to re-grow. Differences in net ecosystem productivity between the fields were mainly caused by a loss of gross primary productivity in the Treatment field; ecosystem respiration was similar for both fields. When biomass removals and manure applications are included in the carbon budget, the Treatment field lost 149 g C m−2 whereas the Control field sequestered 96 g C m−2, for a net difference of 245 g C m−2 over the June to December period (210 d). This suggests that perennial grass converted for annual cropping can lose more carbon than perennial grassland can sequester in a season.

scholarly journals Response of hydrology and CO<sub>2</sub> flux to experimentally-altered rainfall frequency in a temperate poor fen, southern Ontario, Canada

2017 ◽  
Author(s):  
Danielle D. Radu ◽  
Tim P. Duval
Keyword(s):  
Plant Growth ◽  
Ecosystem Respiration ◽  
Vascular Plant ◽  
Moisture Regime ◽  
Co2 Uptake ◽  
Vegetation Types ◽  
Near Surface ◽  
Poor Fen ◽  
Rainfall Frequency ◽  
Strong Control

Abstract. Predicted changes to the precipitation regime in many parts of the world include intensifying the distribution into lower frequency, large magnitude events. The corresponding alterations to the soil moisture regime may affect plant growth and soil respiration, particularly in peatlands, where large stores of organic carbon are due to gross ecosystem productivity (GEP) exceeding ecosystem respiration (ER). This study uses a combined lab and field approach to examine the effect of changing rainfall frequency on peatland moisture controls on CO2 uptake in an undisturbed cool temperate poor fen. Lab monoliths and field plots containing mosses, sedges, or shrubs received either 2.3, 1, or 0.5 events per week, with total rainfall held constant. Decreasing rain frequency led to lower near-surface volumetric moisture content (VMC), water table (WT), and soil tension for all vegetation types, with minimal effect on evapotranspiration. The presence of sedges in particular led to soil tensions > −100 cm of water of a sizeable duration (37 %) of the experiment. Altered rainfall frequencies affected GEP but had little effect on ER: overall low-frequency rain led to reduced net CO2 uptake for all three vegetation types. VMC had a strong control on GEP and net ecosystem exchange (NEE) of the Sphagnum capillifolium monoliths, and decreasing rainfall frequency influenced these relationships. Overall, communities dominated by mosses became net sources of CO2 after three days without rain, whereas sedge communities remained net sinks for up to 14 days without rain. Results of this study demonstrate the hydrological controls of peatland CO2 exchange dynamics influenced by changing precipitation frequency and suggest these predicted changes in frequency will lead to increased vascular plant growth and limit the carbon-sink function of peatlands.

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