Long-term experimentally deepened snow decreases growing-season respiration in a low- and high-arctic tundra ecosystem

2016 ◽  
Vol 121 (5) ◽  
pp. 1236-1248 ◽  
Author(s):  
Philipp R. Semenchuk ◽  
Casper T. Christiansen ◽  
Paul Grogan ◽  
Bo Elberling ◽  
Elisabeth J. Cooper
Keyword(s):  
Growing Season ◽  
Arctic Tundra ◽  
High Arctic ◽  
Tundra Ecosystem

scholarly journals The effect of a permafrost disturbance on growing-season carbon-dioxide fluxes in a high Arctic tundra ecosystem

2015 ◽  
Vol 12 (23) ◽  
pp. 19781-19817
Author(s):  
A. E. Cassidy ◽  
A. Christen ◽  
G. H. R. Henry
Keyword(s):  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Net Ecosystem Exchange ◽  
Growing Season ◽  
Arctic Tundra ◽  
High Arctic ◽  
Carbon Dioxide Fluxes ◽  
Tundra Ecosystem ◽  
Retrogressive Thaw Slump ◽  
Measurement Period

Abstract. Soil carbon stored in high-latitude permafrost landscapes is threatened by warming, and could contribute significant amounts of carbon to the atmosphere and hydrosphere as permafrost thaws. Permafrost disturbances, especially active layer detachments and retrogressive thaw slumps, have increased in frequency and magnitude across the Fosheim Peninsula, Ellesmere Island, Canada. To determine the effects of retrogressive thaw slumps on net ecosystem exchange (NEE) of CO2 in high Arctic tundra, we used two eddy covariance (EC) tower systems to simultaneously and continuously measure CO2 fluxes from a disturbed site and the surrounding undisturbed tundra. During the 32-day measurement period in the 2014 growing season the undisturbed tundra was a small net sink (NEE = −0.12 g C m−2 d−1); however, the disturbed terrain of the retrogressive thaw slump was a net source (NEE = +0.39 g C m−2 d−1). Over the measurement period, the undisturbed tundra sequestered 3.84 g C m−2, while the disturbed tundra released 12.48 g C m−2. Before full leaf out in early July, the undisturbed tundra was a small source of CO2, but shifted to a sink for the remainder of the sampling season (July), whereas the disturbed tundra remained a source of CO2 throughout the season. A static chamber system was also used to measure fluxes in the footprints of the two towers, in both disturbed and undisturbed tundra, and fluxes were partitioned into ecosystem respiration (Re) and gross primary production (GPP). Average GPP and Re found in disturbed tundra were smaller (+0.41 μmol m−2 s−1 and +0.50 μmol m−2 s−1, respectively) than those found in undisturbed tundra (+1.21 μmol m−2 s−1 and +1.00 μmol m−2 s−1, respectively). Our measurements indicated clearly that the permafrost disturbance changed the high Arctic tundra system from a sink to a source for CO2 during the growing season.

scholarly journals The effect of a permafrost disturbance on growing-season carbon-dioxide fluxes in a high Arctic tundra ecosystem

2016 ◽  
Vol 13 (8) ◽  
pp. 2291-2303 ◽  
Author(s):  
Alison E. Cassidy ◽  
Andreas Christen ◽  
Gregory H. R. Henry
Keyword(s):  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Net Ecosystem Exchange ◽  
Growing Season ◽  
Arctic Tundra ◽  
High Arctic ◽  
Carbon Dioxide Fluxes ◽  
Tundra Ecosystem ◽  
Retrogressive Thaw Slump ◽  
Measurement Period

Abstract. Soil carbon stored in high-latitude permafrost landscapes is threatened by warming and could contribute significant amounts of carbon to the atmosphere and hydrosphere as permafrost thaws. Thermokarst and permafrost disturbances, especially active layer detachments and retrogressive thaw slumps, are present across the Fosheim Peninsula, Ellesmere Island, Canada. To determine the effects of retrogressive thaw slumps on net ecosystem exchange (NEE) of CO2 in high Arctic tundra, we used two eddy covariance (EC) tower systems to simultaneously and continuously measure CO2 fluxes from a disturbed site and the surrounding undisturbed tundra. During the 32-day measurement period in the 2014 growing season, the undisturbed tundra was a small net sink (NEE  =  −0.1 g C m−2 d−1); however, the disturbed terrain of the retrogressive thaw slump was a net source (NEE  =  +0.4 g C m−2 d−1). Over the measurement period, the undisturbed tundra sequestered 3.8 g C m−2, while the disturbed tundra released 12.5 g C m−2. Before full leaf-out in early July, the undisturbed tundra was a small source of CO2 but shifted to a sink for the remainder of the sampling season (July), whereas the disturbed tundra remained a source of CO2 throughout the season. A static chamber system was also used to measure daytime fluxes in the footprints of the two towers, in both disturbed and undisturbed tundra, and fluxes were partitioned into ecosystem respiration (Re) and gross primary production (GPP). Average GPP and Re found in disturbed tundra were smaller (+0.40 µmol m−2 s−1 and +0.55 µmol m−2 s−1, respectively) than those found in undisturbed tundra (+1.19 µmol m−2 s−1 and +1.04 µmol m−2 s−1, respectively). Our measurements indicated clearly that the permafrost disturbance changed the high Arctic tundra system from a sink to a source for CO2 during the majority of the growing season (late June and July).

scholarly journals Increased Turnover but Little Change in the Carbon Balance of High-Arctic Tundra Exposed to Whole Growing Season Warming

2004 ◽  
Vol 36 (3) ◽  
pp. 298-307 ◽  
Author(s):  
Fleur L. Marchand ◽  
Ivan Nijs ◽  
Hans J. de Boeck ◽  
Fred Kockelbergh ◽  
Sofie Mertens ◽  
...  
Keyword(s):  
Carbon Balance ◽  
Growing Season ◽  
Arctic Tundra ◽  
High Arctic

scholarly journals Partitioning net ecosystem exchange of CO<sub>2</sub> on the pedon scale in the Lena River Delta, Siberia

2019 ◽  
Vol 16 (7) ◽  
pp. 1543-1562 ◽  
Author(s):  
Tim Eckhardt ◽  
Christian Knoblauch ◽  
Lars Kutzbach ◽  
David Holl ◽  
Gillian Simpson ◽  
...  
Keyword(s):  
Growing Season ◽  
Arctic Tundra ◽  
River Delta ◽  
Environmental Drivers ◽  
Co2 Fluxes ◽  
Lena River ◽  
Hydrological Conditions ◽  
Tundra Ecosystem ◽  
Water Saturated ◽  
Lena River Delta

Abstract. Arctic tundra ecosystems are currently facing amplified rates of climate warming. Since these ecosystems store significant amounts of soil organic carbon, which can be mineralized to carbon dioxide (CO2) and methane (CH4), rising temperatures may cause increasing greenhouse gas fluxes to the atmosphere. To understand how net the ecosystem exchange (NEE) of CO2 will respond to changing climatic and environmental conditions, it is necessary to understand the individual responses of the processes contributing to NEE. Therefore, this study aimed to partition NEE at the soil–plant–atmosphere interface in an arctic tundra ecosystem and to identify the main environmental drivers of these fluxes. NEE was partitioned into gross primary productivity (GPP) and ecosystem respiration (Reco) and further into autotrophic (RA) and heterotrophic respiration (RH). The study examined CO2 flux data collected during the growing season in 2015 using closed-chamber measurements in a polygonal tundra landscape in the Lena River Delta, northeastern Siberia. To capture the influence of soil hydrology on CO2 fluxes, measurements were conducted at a water-saturated polygon center and a well-drained polygon rim. These chamber-measured fluxes were used to model NEE, GPP, Reco, RH, RA, and net primary production (NPP) at the pedon scale (1–10 m) and to determine cumulative growing season fluxes. Here, the response of in situ measured RA and RH fluxes from permafrost-affected soils of the polygonal tundra to hydrological conditions have been examined. Although changes in the water table depth at the polygon center sites did not affect CO2 fluxes from RH, rising water tables were linked to reduced CO2 fluxes from RA. Furthermore, this work found the polygonal tundra in the Lena River Delta to be a net sink for atmospheric CO2 during the growing season. The NEE at the wet, depressed polygon center was more than twice that at the drier polygon rim. These differences between the two sites were caused by higher GPP fluxes due to a higher vascular plant density and lower Reco fluxes due to oxygen limitation under water-saturated conditions at the polygon center in comparison to the rim. Hence, soil hydrological conditions were one of the key drivers for the different CO2 fluxes across this highly heterogeneous tundra landscape.

scholarly journals Two years with extreme and little snowfall: effects on energy partitioning and surface energy exchange in a high-Arctic tundra ecosystem

2016 ◽  
Vol 10 (4) ◽  
pp. 1395-1413 ◽  
Author(s):  
Christian Stiegler ◽  
Magnus Lund ◽  
Torben Røjle Christensen ◽  
Mikhail Mastepanov ◽  
Anders Lindroth
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Snow Cover ◽  
Energy Exchange ◽  
Surface Energy Balance ◽  
Arctic Tundra ◽  
High Arctic ◽  
Snow Accumulation ◽  
Heat Fluxes ◽  
Tundra Ecosystem

Abstract. Snow cover is one of the key factors controlling Arctic ecosystem functioning and productivity. In this study we assess the impact of strong variability in snow accumulation during 2 subsequent years (2013–2014) on the land–atmosphere interactions and surface energy exchange in two high-Arctic tundra ecosystems (wet fen and dry heath) in Zackenberg, Northeast Greenland. We observed that record-low snow cover during the winter 2012/2013 resulted in a strong response of the heath ecosystem towards low evaporative capacity and substantial surface heat loss by sensible heat fluxes (H) during the subsequent snowmelt period and growing season. Above-average snow accumulation during the winter 2013/2014 promoted summertime ground heat fluxes (G) and latent heat fluxes (LE) at the cost of H. At the fen ecosystem a more muted response of LE, H and G was observed in response to the variability in snow accumulation. Overall, the differences in flux partitioning and in the length of the snowmelt periods and growing seasons during the 2 years had a strong impact on the total accumulation of the surface energy balance components. We suggest that in a changing climate with higher temperature and more precipitation the surface energy balance of this high-Arctic tundra ecosystem may experience a further increase in the variability of energy accumulation, partitioning and redistribution.

scholarly journals Modelling of growing season methane fluxes in a high-Arctic wet tundra ecosystem 1997–2010 using in situ and high-resolution satellite data

Tellus B ◽  
2013 ◽  
Vol 65 (1) ◽  
pp. 19722 ◽  
Author(s):  
Torbern Tagesson ◽  
Mikhail Mastepanov ◽  
Meelis Mölder ◽  
Mikkel P. Tamstorf ◽  
Lars Eklundh ◽  
...  
Keyword(s):  
High Resolution ◽  
Satellite Data ◽  
Growing Season ◽  
High Arctic ◽  
Tundra Ecosystem ◽  
Methane Fluxes

scholarly journals Soil organic carbon depletion and degradation in surface soil after long-term non-growing season warming in High Arctic Svalbard

2019 ◽  
Vol 646 ◽  
pp. 158-167 ◽  
Author(s):  
Philipp R. Semenchuk ◽  
Eveline J. Krab ◽  
Mattias Hedenström ◽  
Carly A. Phillips ◽  
Francisco J. Ancin-Murguzur ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Surface Soil ◽  
Growing Season ◽  
High Arctic

scholarly journals Quantifying Muskox Plant Biomass Removal and Spatial Relocation of Nitrogen in a High Arctic Tundra Ecosystem

2016 ◽  
Vol 48 (2) ◽  
pp. 229-240 ◽  
Author(s):  
Jesper B. Mosbacher ◽  
Ditte K. Kristensen ◽  
Anders Michelsen ◽  
Mikkel Stelvig ◽  
Niels M. Schmidt
Keyword(s):  
Plant Biomass ◽  
Arctic Tundra ◽  
High Arctic ◽  
Tundra Ecosystem ◽  
Biomass Removal
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