Contrasting carbon dioxide fluxes between a drying shrub wetland in Northern Wisconsin, USA, and nearby forests

Abstract. Wetland biogeochemistry is strongly influenced by water and temperature dynamics, and these interactions are currently poorly represented in ecosystem and climate models. A decline in water table of approximately 30 cm was observed at a wetland in Northern Wisconsin, USA over a period from 2001–2007, which was highly correlated with an increase in daily soil temperature variability. Eddy covariance measurements of carbon dioxide exchange were compared with measured CO2 fluxes at two nearby forests in order to distinguish wetland effects from regional trends. As wetland water table declined, both ecosystem respiration and ecosystem production increased by over 20% at the wetland, while forest CO2 fluxes had no significant trends. Net ecosystem exchange of carbon dioxide at the wetland was not correlated with water table, but wetland evapotranspiration decreased substantially as the water table declined. These results suggest that changes in hydrology may not have a large impact on shrub wetland carbon balance over inter-annual time scales due to opposing responses in both ecosystem respiration and productivity.

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The impact of a declining water table on observed carbon fluxes at a northern temperate wetland

Biogeosciences Discussions ◽

10.5194/bgd-6-2659-2009 ◽

2009 ◽

Vol 6 (1) ◽

pp. 2659-2696 ◽

Cited By ~ 4

Author(s):

B. N. Sulman ◽

A. R. Desai ◽

B. D. Cook ◽

N. Saliendra ◽

D. S. Mackay

Keyword(s):

Water Table ◽

Climate Models ◽

Ecosystem Respiration ◽

Net Ecosystem Exchange ◽

High Water ◽

Carbon Dioxide Exchange ◽

Yearly Average ◽

Ecosystem Water Use Efficiency ◽

Wetland Biogeochemistry ◽

The Impact

Abstract. Wetland biogeochemistry is strongly influenced by water and temperature dynamics, and these interactions are currently poorly represented in ecosystem and climate models. A decline in water table of approximately 6 cm/year was observed at a wetland in northern Wisconsin, USA over a period from 2001–2007. Eddy covariance measurements of carbon dioxide exchange in conjunction with the declining water table revealed an increase in ecosystem respiration of over 20% as water table depth fell through a range between 5 and 35 cm below the surface. Ecosystem respiration was not correlated with water table outside of this range. The limits of the range were dependent on temperature, with the effect of water table penetrating deeper at higher temperatures. Yearly average ecosystem production was approximately 20% higher in years with low water table than in years with high water table. As the water table declined, evapotranspiration decreased and ecosystem water use efficiency increased. Wetland net ecosystem exchange was not correlated with water table, but in 2007, a year with an exceptionally dry growing season, the wetland site was a net carbon source. These results suggest that changes in hydrology may not have a large impact on wetland carbon flux over inter-annual time scales due to opposing responses in both ecosystem respiration and productivity. However, this balance appears to be sensitive to changes in the seasonal distribution of precipitation.

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MODELING OF THE SEASONAL COURSE OF CARBON EXCHANGE IN WETLAND ECOSYSTEMS

Ecology Economy Informatics System analysis and mathematical modeling of ecological and economic systems ◽

10.23885/2500-395x-2020-1-5-56-61 ◽

2020 ◽

Vol 1 (5) ◽

pp. 56-61

Author(s):

E. A. Dyukarev ◽

◽

Keyword(s):

Carbon Dioxide ◽

Western Siberia ◽

Ecosystem Respiration ◽

Net Ecosystem Exchange ◽

Growing Season ◽

Biological Productivity ◽

Carbon Dioxide Fluxes ◽

Wetland Ecosystems ◽

Bog Ecosystems ◽

Two Parameters

The paper summarizes the results of expeditionary studies to study biological productivity, carbon dioxide fluxes in the bog ecosystems of the Central Taiga of Western Siberia. The paper summarizes the results of expeditionary studies to study biological productivity, carbon dioxide fluxes in the bog ecosystems of the Central Taiga of Western Siberia. Measurements of carbon dioxide fluxes were carried out from July 7 to July 14, 2019 at six observation sites located on the territory of typical wetland ecosystems of eutrophic, mesotrophic and oligotrophic types, taking into account the diversity of microlandscapes. Automatic measurements of the CO2 fluxes were carried out using the Licor LI-8100A soil respiration system. To extend the obtained observation data to other periods and to calculate the annual carbon balance of the ecosystem, a net ecosystem exchange (NEE) model was proposed, and the net fluxes of greenhouse gases for the growing season were calculated. The model uses air temperature and incoming photosynthetically active radiation as explanatory factors for gross primary production and ecosystem respiration. The model was calibrated in accordance with field measurements of carbon dioxide fluxes. For each observation site, six parameters were determined: two parameters for the photosynthesis model, two parameters for the respiration model and two for the biomass growth model. As a result of calculations for the period from May to October 2019, time series of fluxes of carbon dioxide absorption by vegetation during photosynthesis, CO2 release during ecosystem respiration, and the resulting flux – net ecosystem exchange were obtained. In the annual course, an increase in the intensity of photosynthesis during the daytime is associated with both the annual course of solar radiation and the accumulation of plant biomass. It was found that the net ecosystem exchange varies more strongly than its components. The NEE for ecosystems without vegetation is always positive. NEE is negative for the hollow and the open transit mesotrophic fen on any day of the growing season. Other ecosystems show both positive and negative daily mean fluxes. Wetland ecosystems with large biomass storages have significant fluxes (more than 1500 g CO2 / m2 ) associated with photosynthesis, but they also have a large expenditure component of carbon exchange (750–2200 g / m2 ). As a result, it was found that the greatest total absorption of carbon dioxide is observed in the mesotrophic sedge- menyanthes fen (1062 g / m2 ) and in the low ryam, taking into account the tree layer (603 g / m2 ). Other wetlands accumulate 244–466 g / m2 from the atmosphere during the growing season.

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Assessing the impact of exceptional inter-annual climatic variability on rates of net ecosystem carbon dioxide exchange at Clara bog.

10.5194/egusphere-egu21-13414 ◽

2021 ◽

Author(s):

Matthew Saunders ◽

Ruchita Ingle ◽

Shane Regan

Keyword(s):

Water Table ◽

Elevated Temperatures ◽

Ecosystem Respiration ◽

Anthropogenic Activities ◽

Climatic Variability ◽

Growing Season ◽

Carbon Dioxide Exchange ◽

Mean Annual Temperature ◽

Monitoring Networks ◽

The Impact

Peatland ecosystems are integral to the mitigation of climate change as they represent significant terrestrial carbon sinks. In Ireland, peatlands cover ~20% of the land area but hold up to 75% of the soil organic carbon stock however many of these ecosystems (~85% of the total area) have been degraded due to anthropogenic activities such as agriculture, forestry and extraction for horticulture or energy. Furthermore, the carbon stocks that remain in these systems are vulnerable to inter-annual variation in climate, such as changes in precipitation and temperature, which can alter the hydrological status of these systems leading to changes in key biogeochemical processes and carbon and greenhouse gas exchange.&#160; During 2018 exceptional drought and heatwave conditions were reported across Northwestern Europe, where reductions in precipitation coupled with elevated temperatures were observed. Exceptional inter-annual climatic variability was also observed at Clara bog, a near natural raised bog in the Irish midlands when data from 2018 and 2019 were compared. Precipitation in 2018 was ~300 mm lower than 2019 while the average mean annual temperature was 0.5&#176;C higher. The reduction in precipitation, particularly during the growing season in 2018, consistently lowered the water table where ~150 consecutive days where the water table was >5cm below the surface of the bog were observed at the central ecotope location. The differing hydrological conditions between years resulted in the study area, as determined by the flux footprint of the eddy covariance tower, acting as a net source of carbon of 53.5 g C m-2 in 2018 and a net sink of 125.2 g C m-2 in 2019. The differences in the carbon dynamics between years were primarily driven by enhanced ecosystem respiration (Reco) and lower rates of Gross Primary Productivity (GPP) in the drier year, where the maximum monthly ratio of GPP:Reco during the growing season was 0.96 g C m-2 month in 2018 and 1.14 g C m-2 month in 2019. This study highlights both the vulnerability and resilience of these ecosystems to exceptional inter-annual climatic variability and emphasises the need for long-term monitoring networks to enhance our understanding of the impacts of these events when they occur.

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Evaluating terrestrial CO2 flux diagnoses and uncertainties from a simple land surface model and its residuals

Biogeosciences ◽

10.5194/bg-11-217-2014 ◽

2014 ◽

Vol 11 (2) ◽

pp. 217-235 ◽

Cited By ~ 16

Author(s):

T. W. Hilton ◽

K. J. Davis ◽

K. Keller

Keyword(s):

Carbon Dioxide ◽

Parameter Estimation ◽

North American ◽

Land Surface ◽

Atmospheric Carbon Dioxide ◽

Ecosystem Respiration ◽

Land Surface Model ◽

Net Ecosystem Exchange ◽

Surface Model ◽

Considerable Uncertainty

Abstract. Global terrestrial atmosphere–ecosystem carbon dioxide fluxes are well constrained by the concentration and isotopic composition of atmospheric carbon dioxide. In contrast, considerable uncertainty persists surrounding regional contributions to the net global flux as well as the impacts of atmospheric and biological processes that drive the net flux. These uncertainties severely limit our ability to make confident predictions of future terrestrial biological carbon fluxes. Here we use a simple light-use efficiency land surface model (the Vegetation Photosynthesis Respiration Model, VPRM) driven by remotely sensed temperature, moisture, and phenology to diagnose North American gross ecosystem exchange (GEE), ecosystem respiration, and net ecosystem exchange (NEE) for the period 2001 to 2006. We optimize VPRM parameters to eddy covariance (EC) NEE observations from 65 North American FluxNet sites. We use a separate set of 27 cross-validation FluxNet sites to evaluate a range of spatial and temporal resolutions for parameter estimation. With these results we demonstrate that different spatial and temporal groupings of EC sites for parameter estimation achieve similar sum of squared residuals values through radically different spatial patterns of NEE. We also derive a regression model to estimate observed VPRM errors as a function of VPRM NEE, temperature, and precipitation. Because this estimate is based on model-observation residuals it is comprehensive of all the error sources present in modeled fluxes. We find that 1 km interannual variability in VPRM NEE is of similar magnitude to estimated 1 km VPRM NEE errors.

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Carbon Dioxide Fluxes and Carbon Stocks under Conservation Agricultural Practices in South Africa

Agriculture ◽

10.3390/agriculture10090374 ◽

2020 ◽

Vol 10 (9) ◽

pp. 374 ◽

Cited By ~ 2

Author(s):

Patrick Nyambo ◽

Chiduza Cornelius ◽

Tesfay Araya

Keyword(s):

South Africa ◽

Carbon Dioxide ◽

Soil Moisture ◽

Carbon Stock ◽

Crop Residue ◽

Agricultural Practices ◽

Carbon Stocks ◽

Residue Management ◽

Co2 Fluxes ◽

Carbon Dioxide Fluxes

Understanding the impacts of agricultural practices on carbon stocks and CO2 emission is imperative in order to recommend low emission strategies. The objective of this study was to investigate the effects of tillage, crop rotation, and residue management on soil CO2 fluxes, carbon stock, soil temperature, and moisture in the semi-arid conditions in the Eastern Cape of South Africa. The field trial was laid out as a split-split-plot design replicated three times. The main plots were tillage viz conventional tillage (CT) and no-till (NT). The sub-plots were allocated to crop rotations viz maize–fallow–maize (MFM), maize–oat–maize (MOM), and maize–vetch–maize (MVM). Crop residue management was in the sub-sub plots, viz retention (R+), removal (R−), and biochar (B). There were no significant interactions (p > 0.05) with respect to the cumulative CO2 fluxes, soil moisture, and soil temperature. Crop residue retention significantly increased the soil moisture content relative to residue removal, but was not different to biochar application. Soil tilling increased the CO2 fluxes by approximately 26.3% relative to the NT. The carbon dioxide fluxes were significantly lower in R− (2.04 µmoL m−2 s−1) relative to the R+ (2.32 µmoL m−2 s−1) and B treatments (2.36 µmoL m−2 s−1). The carbon dioxide fluxes were higher in the summer (October–February) months compared to the winter period (May–July), irrespective of treatment factors. No tillage had a significantly higher carbon stock at the 0-5 cm depth relative to CT. Amending the soils with biochar resulted in significantly lower total carbon stock relative to both R+ and R−. The results of the study show that NT can potentially reduce CO2 fluxes. In the short term, amending soils with biochar did not reduce the CO2 fluxes compared to R+, however the soil moisture increases were comparable.

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From sink to source: long-term (2002-2019) trends and anomalies in net ecosystem exchange of CO2 from a Scottish temperate peatland.

10.5194/egusphere-egu2020-5967 ◽

2020 ◽

Author(s):

Karen Hei-Laan Yeung ◽

Carole Helfter ◽

Neil Mullinger ◽

Mhairi Coyle ◽

Eiko Nemitz

Keyword(s):

Water Table ◽

Ecosystem Respiration ◽

Net Ecosystem Exchange ◽

Growing Season ◽

Water Table Depth ◽

Sink Strength ◽

Summer Drought ◽

C Cycle ◽

Dry Spell

Peatlands North of 45&#730; represent one of the largest terrestrial carbon (C) stores. They play an important role in the global C-cycle, and their ability to sequester carbon is controlled by multiple, often competing, factors including precipitation, temperature and phenology. Land-atmosphere exchange of carbon dioxide (CO2) is dynamic, and exhibits marked seasonal and inter-annual variations which can effect the overall carbon sink strength in both the short- and long-term.Due to increased incidences of climate anomalies in recent years, long-term datasets are essential to disambiguate natural variability in Net Ecosystem Exchange (NEE) from shorter-term fluctuations. This is particularly important at high latitudes (>45&#730;N) where the majority of global peatlands are found. With increasing pressure from stressors such as climate and land-use change, it has been predicted that with a ca. 3oC global temperature rise by 2100, UK peatlands could become a net source of C.NEE of CO2 has been measured using the eddy-covariance (EC) method at Auchencorth Moss (55&#176;47&#8217;32 N, 3&#176;14&#8217;35 W, 267 m a.s.l.), a temperate, lowland, ombrotrophic peatland in central Scotland, continuously since 2002. Alongside EC data, we present a range of meteorological parameters measured at site including soil temperature, total solar and photosynthetically active radiation (PAR), rainfall, and, since April 2007, half-hourly water table depth readings. The length of record and range of measurements make this dataset an important resource as one of the longest term records of CO2 fluxes from a temperate peatland.Although seasonal cycles of gross primary productivity (GPP) were highly variable between years, the site was a consistent CO2 sink for the period 2002-2012. However, net annual losses of CO2 have been recorded on several occasions since 2013. Whilst NEE tends to be positively correlated with the length of growing season, anomalies in winter weather also explain some of the variability in CO2 sink strength the following summer.Additionally, water table depth (WTD) plays a crucial role, affecting both GPP and ecosystem respiration (Reco). Relatively dry summers in recent years have contributed to shifting the balance between Reco and GPP: prolonged periods of low WTD were typically accompanied by an increase in Reco, and a decrease in GPP, hence weakening the overall CO2 sink strength. Extreme events such as drought periods and cold winter temperatures can have significant and complex effects on NEE, particularly when such meteorological anomalies co-occur. For example, a positive annual NEE occurred in 2003 when Europe experienced heatwave and summer drought. More recently, an unusually long spell of snow lasting until the end of March delayed the onset of the 2018 growing season by up to 1.5 months compared to previous years. This was followed by a prolonged dry spell in summer 2018, which weakened GPP, increased Reco and led to a net annual loss of 47.4 ton CO2-C km-2. It is clear that the role of Northern peatlands within the carbon cycle is being modified, driven by changes in climate at both local and global scales.

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Seasonal variations in carbon dioxide exchange in an alpine wetland meadow on the Qinghai-Tibetan Plateau

Biogeosciences ◽

10.5194/bg-7-1207-2010 ◽

2010 ◽

Vol 7 (4) ◽

pp. 1207-1221 ◽

Cited By ~ 59

Author(s):

L. Zhao ◽

J. Li ◽

S. Xu ◽

H. Zhou ◽

Y. Li ◽

...

Keyword(s):

Carbon Dioxide ◽

Tibetan Plateau ◽

Carbon Sink ◽

Ecosystem Respiration ◽

Gross Primary Production ◽

Carbon Dioxide Exchange ◽

Research Station ◽

Rain Event ◽

Area Index ◽

Alpine Wetland

Abstract. Alpine wetland meadow could functions as a carbon sink due to it high soil organic content and low decomposition. However, the magnitude and dynamics of carbon stock in alpine wetland ecosystems are not well quantified. Therefore, understanding how environmental variables affect the processes that regulate carbon fluxes in alpine wetland meadow on the Qinghai-Tibetan Plateau is critical. To address this issue, Gross Primary Production (GPP), Ecosystem Respiration (Reco), and Net Ecosystem Exchange (NEE) were examined in an alpine wetland meadow using the eddy covariance method from October 2003 to December 2006 at the Haibei Research Station of the Chinese Academy of Sciences. Seasonal patterns of GPP and Reco were closely associated with leaf area index (LAI). The Reco showed a positive exponential to soil temperature and relatively low Reco occurred during the non-growing season after a rain event. This result is inconsistent with the result observed in alpine shrubland meadow. In total, annual GPP were estimated at 575.7, 682.9, and 630.97 g C m−2 in 2004, 2005, and 2006, respectively. Meanwhile, the Reco were equal to 676.8, 726.4, 808.2 g C m−2, and thus the NEE were 101.1, 44.0 and 173.2 g C m−2. These results indicated that the alpine wetland meadow was a moderately source of carbon dioxide (CO2). The observed carbon dioxide fluxes in the alpine wetland meadow were higher than other alpine meadow such as Kobresia humilis meadow and shrubland meadow.

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