Environmental control of net ecosystem CO2 exchange in a treed, moderately rich fen in northern Alberta

Syed, Kamran H.; Flanagan, Lawrence B.; Carlson, Peter J.; Glenn, Aaron J.; Gaalen, K. Eric Van

doi:10.1016/j.agrformet.2006.03.022

Cited by 115 publications

(161 citation statements)

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“…Syed et al (2006) reported ER, GEP, and NEE of 1.5, 1.89, and −0.38 µmol m −2 s −1 in a wetland dominated by shrubs and stunted trees, and Humphreys et al (2006) also reported fluxes of similar magnitudes in a comparison of several northern wetland sites. Both these studies also observed a strong correlation between ER and GEP, which our results confirm at our wetland site.…”

Section: Discussionmentioning

confidence: 87%

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

et al. 2009

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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 CO 2 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 CO 2 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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Section: Discussionmentioning

confidence: 87%

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

et al. 2009

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“…The only site with a large bias in annual NEP was AB-Fen. Observation-based estimations of NEP in this fen were extremely high, totalling 176 g C from May to October, in comparison with other sites (Syed et al, 2006). This treed fen had a high peat density and LAI and large variation in the WTD, which, accompanied by high spring temperatures, resulted in high ecosystem photosynthesis capacity and production .…”

Section: Annual Net Ecosystem Productionmentioning

confidence: 87%

Integrating peatlands into the coupled Canadian Land Surface Scheme (CLASS) v3.6 and the Canadian Terrestrial Ecosystem Model (CTEM) v2.0

Verseghy

Melton

2016

Geosci. Model Dev.

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Abstract. Peatlands, which contain large carbon stocks that must be accounted for in the global carbon budget, are poorly represented in many earth system models. We integrated peatlands into the coupled Canadian Land Surface Scheme (CLASS) and the Canadian Terrestrial Ecosystem Model (CTEM), which together simulate the fluxes of water, energy, and CO 2 at the land surface-atmosphere boundary in the family of Canadian Earth system models (CanESMs). New components and algorithms were added to represent the unique features of peatlands, such as their characteristic ground floor vegetation (mosses), the slow decomposition of carbon in the water-logged soils and the interaction between the water, energy, and carbon cycles. This paper presents the modifications introduced into the CLASS-CTEM modelling framework together with site-level evaluations of the model performance for simulated water, energy and carbon fluxes at eight different peatland sites. The simulated daily gross primary production (GPP) and ecosystem respiration are well correlated with observations, with values of the Pearson correlation coefficient higher than 0.8 and 0.75 respectively. The simulated mean annual net ecosystem production at the eight test sites is 87 g C m −2 yr −1 , which is 22 g C m −2 yr −1 higher than the observed annual mean. The general peatland model compares well with other site-level and regional-level models for peatlands, and is able to represent bogs and fens under a range of climatic and geographical conditions.

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“…However, a higher yearly CO 2 accumulation rate of −144 g C m −2 in a treed fen in the same boreal region is reported by Syed et al (2006). Methane (CH 4 ) is also an important component of the C balance in peatland ecosystems.…”

Section: Discussionmentioning

confidence: 99%

Carbon dioxide flux and net primary production of a boreal treed bog: Responses to warming and water-table-lowering simulations of climate change

et al. 2015

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Abstract. Midlatitude treed bogs represent significant carbon (C) stocks and are highly sensitive to global climate change. In a dry continental treed bog, we compared three sites: control, recent (1-3 years; experimental) and older drained (10-13 years), with water levels at 38, 74 and 120 cm below the surface, respectively. At each site we measured carbon dioxide (CO 2 ) fluxes and estimated tree root respiration (R r ; across hummock-hollow microtopography of the forest floor) and net primary production (NPP) of trees during the growing seasons (May to October) of 2011-2013. The CO 2 -C balance was calculated by adding the net CO 2 exchange of the forest floor (NE ff − R r ) to the NPP of the trees.From cooler and wetter 2011 to the driest and the warmest 2013, the control site was a CO 2 -C sink of 92, 70 and 76 g m −2 , the experimental site was a CO 2 -C source of 14, 57 and 135 g m −2 , and the drained site was a progressively smaller source of 26, 23 and 13 g CO 2 -C m −2 . The short-term drainage at the experimental site resulted in small changes in vegetation coverage and large net CO 2 emissions at the microforms. In contrast, the longer-term drainage and deeper water level at the drained site resulted in the replacement of mosses with vascular plants (shrubs) on the hummocks and lichen in the hollows leading to the highest CO 2 uptake at the drained hummocks and significant losses in the hollows. The tree NPP (including above-and belowground growth and litter fall) in 2011 and 2012 was significantly higher at the drained site (92 and 83 g C m −2 ) than at the experimental (58 and 55 g C m −2 ) and control (52 and 46 g C m −2 ) sites.We also quantified the impact of climatic warming at all water table treatments by equipping additional plots with open-top chambers (OTCs) that caused a passive warming on average of ∼ 1 • C and differential air warming of ∼ 6 • C at midday full sun over the study years. Warming significantly enhanced shrub growth and the CO 2 sink function of the drained hummocks (exceeding the cumulative respiration losses in hollows induced by the lowered water level × warming). There was an interaction of water level with warming across hummocks that resulted in the largest net CO 2 uptake at the warmed drained hummocks. Thus in 2013, the warming treatment enhanced the sink function of the control site by 13 g m −2 , reduced the source function of the experimental by 10 g m −2 and significantly enhanced the sink function of the drained site by 73 g m −2 . Therefore, drying and warming in continental bogs is expected to initially accelerate CO 2 -C losses via ecosystem respiration, but persistent drought and warming is expected to restore the peatland's original CO 2 -C sink function as a result of the shifts in vegetation composition and productivity between the microforms and increased NPP of trees over time.

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Environmental control of net ecosystem CO2 exchange in a treed, moderately rich fen in northern Alberta

Cited by 115 publications

References 53 publications

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

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

Integrating peatlands into the coupled Canadian Land Surface Scheme (CLASS) v3.6 and the Canadian Terrestrial Ecosystem Model (CTEM) v2.0

Carbon dioxide flux and net primary production of a boreal treed bog: Responses to warming and water-table-lowering simulations of climate change

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