scholarly journals The current state of CO2 flux chamber studies in the Arctic tundra

2017 ◽  
Vol 42 (2) ◽  
pp. 162-184 ◽  
Author(s):  
Anna-Maria Virkkala ◽  
Tarmo Virtanen ◽  
Aleksi Lehtonen ◽  
Janne Rinne ◽  
Miska Luoto
Keyword(s):  
Carbon Balance ◽  
Ecosystem Respiration ◽  
Vegetation Type ◽  
Gross Primary Production ◽  
Co2 Flux ◽  
Arctic Tundra ◽  
The Arctic ◽  
Environmental Drivers ◽  
Soil Conditions ◽  
Flux Chamber

The Arctic tundra plays an important role in the carbon cycle as it stores 50% of global soil organic carbon reservoirs. The processes (fluxes) regulating these stocks are predicted to change due to direct and indirect effects of climate change. Understanding the current and future carbon balance calls for a summary of the level of knowledge regarding chamber-derived carbon dioxide (CO2) flux studies. Here, we describe progress from recently (2000–2016) published studies of growing-season CO2 flux chamber measurements, namely GPP (gross primary production), ER (ecosystem respiration), and NEE (net ecosystem exchange), in the tundra region. We review the study areas and designs along with the explanatory environmental drivers used. Most of the studies were conducted in Alaska and Fennoscandia, and we stress the need for measuring fluxes in other tundra regions, particularly in more extreme climatic, productivity, and soil conditions. Soil respiration and other greenhouse gas measurements were seldom included in the studies. Although most of the environmental drivers of CO2 fluxes have been relatively well investigated (such as the effect of vegetation type and soil microclimate on fluxes), soil nutrients, other greenhouse gases and disturbance regimes require more research as they might define the future carbon balance. Particular attention should be paid to the effects of shrubification, geomorphology, and other disturbance effects such as fire events, and disease and herbivore outbreaks. An improved conceptual framework and understanding of underlying processes of biosphere–atmosphere CO2 exchange will provide more information on carbon cycling in the tundra.

scholarly journals Microscale drivers of summer CO2 fluxes in the Svalbard High Arctic tundra

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Marta Magnani ◽  
Ilaria Baneschi ◽  
Mariasilvia Giamberini ◽  
Brunella Raco ◽  
Antonello Provenzale
Keyword(s):  
Ecosystem Respiration ◽  
Vegetation Type ◽  
Gross Primary Production ◽  
Arctic Tundra ◽  
High Arctic ◽  
The Arctic ◽  
Small Scale ◽  
Arctic Ecosystems ◽  
Additional Source ◽  
And Storage

AbstractHigh-Arctic ecosystems are strongly affected by climate change, and it is still unclear whether they will become a carbon source or sink in the next few decades. In turn, such knowledge gaps on the drivers and the processes controlling CO2 fluxes and storage make future projections of the Arctic carbon budget a challenging goal. During summer 2019, we extensively measured CO2 fluxes at the soil–vegetation–atmosphere interface, together with basic meteoclimatic variables and ecological characteristics in the Bayelva river basin near Ny Ålesund, Spitzbergen, Svalbard (NO). By means of multi-regression models, we identified the main small-scale drivers of CO2 emission (Ecosystem Respiration, ER), and uptake (Gross Primary Production, GPP) in this tundra biome, showing that (i) at point scale, the temporal variability of fluxes is controlled by the classical drivers, i.e. air temperature and solar irradiance respectively for ER and GPP, (ii) at site scale, the heterogeneity of fractional vegetation cover, soil moisture and vegetation type acted as additional source of variability for both CO2 emissions and uptake. The assessment of the relative importance of such drivers in the multi-regression model contributes to a better understanding of the terrestrial carbon dioxide exchanges and of Critical Zone processes in the Arctic tundra.

scholarly journals Effects of a windthrow disturbance on the carbon balance of a broadleaf deciduous forest in Hokkaido, Japan

2015 ◽  
Vol 12 (23) ◽  
pp. 6837-6851 ◽  
Author(s):  
K. Yamanoi ◽  
Y. Mizoguchi ◽  
H. Utsugi
Keyword(s):  
Forest Management ◽  
Carbon Balance ◽  
Deciduous Forest ◽  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Co2 Flux ◽  
White Birch ◽  
Eddy Covariance Method ◽  
Area Index

Abstract. Forests play an important role in the terrestrial carbon balance, with most being in a carbon sequestration stage. The net carbon releases that occur result from forest disturbance, and windthrow is a typical disturbance event affecting the forest carbon balance in eastern Asia. The CO2 flux has been measured using the eddy covariance method in a deciduous broadleaf forest (Japanese white birch, Japanese oak, and castor aralia) in Hokkaido, where incidental damage by the strong Typhoon Songda in 2004 occurred. We also used the biometrical method to demonstrate the CO2 flux within the forest in detail. Damaged trees amounted to 40 % of all trees, and they remained on site where they were not extracted by forest management. Gross primary production (GPP), ecosystem respiration (Re), and net ecosystem production were 1350, 975, and 375 g C m−2 yr−1 before the disturbance and 1262, 1359, and −97 g C m−2 yr−1 2 years after the disturbance, respectively. Before the disturbance, the forest was an evident carbon sink, and it subsequently transformed into a net carbon source. Because of increased light intensity at the forest floor, the leaf area index and biomass of the undergrowth (Sasa kurilensis and S. senanensis) increased by factors of 2.4 and 1.7, respectively, in 3 years subsequent to the disturbance. The photosynthesis of Sasa increased rapidly and contributed to the total GPP after the disturbance. The annual GPP only decreased by 6 % just after the disturbance. On the other hand, the annual Re increased by 39 % mainly because of the decomposition of residual coarse-wood debris. The carbon balance after the disturbance was controlled by the new growth and the decomposition of residues. The forest management, which resulted in the dead trees remaining at the study site, strongly affected the carbon balance over the years. When comparing the carbon uptake efficiency at the study site with that at others, including those with various kinds of disturbances, we emphasized the importance of forest management as well as disturbance type in the carbon balance.

scholarly journals Can land degradation drive differences in the C exchange of two similar semiarid ecosystems?

2018 ◽  
Vol 15 (1) ◽  
pp. 263-278 ◽  
Author(s):  
Ana López-Ballesteros ◽  
Cecilio Oyonarte ◽  
Andrew S. Kowalski ◽  
Penélope Serrano-Ortiz ◽  
Enrique P. Sánchez-Cañete ◽  
...  
Keyword(s):  
Vadose Zone ◽  
Land Degradation ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Co2 Flux ◽  
C Sequestration ◽  
Co2 Exchange ◽  
Striking Difference ◽  
Soil Variables ◽  
Natural Site

Abstract. Currently, drylands occupy more than one-third of the global terrestrial surface and are recognized as areas vulnerable to land degradation. The concept of land degradation stems from the loss of an ecosystem's biological productivity due to long-term loss of natural vegetation or depletion of soil nutrients. Drylands' key role in the global carbon (C) balance has been recently demonstrated, but the effects of land degradation on C sequestration by these ecosystems still need to be investigated. In the present study, we compared net C and water vapor fluxes, together with satellite, meteorological and vadose zone (CO2, water content and temperature) measurements, between two nearby (∼ 23 km) experimental sites representing “natural” (i.e., site of reference) and “degraded” grazed semiarid grasslands. We utilized data acquired over 6 years from two eddy covariance stations located in southeastern Spain with highly variable precipitation magnitude and distribution. Results show a striking difference in the annual C balances with an average net CO2 exchange of 196 ± 40 (C release) and −23 ± 2 g C m−2 yr−1 (C fixation) for the degraded and natural sites, respectively. At the seasonal scale, differing patterns in net CO2 fluxes were detected over both growing and dry seasons. As expected, during the growing seasons, greater net C uptake over longer periods was observed at the natural site. However, a much greater net C release, probably derived from subterranean ventilation, was measured at the degraded site during drought periods. After subtracting the nonbiological CO2 flux from net CO2 exchange, flux partitioning results point out that, during the 6 years of study, gross primary production, ecosystem respiration and water use efficiency were, on average, 9, 2 and 10 times higher, respectively, at the natural site versus the degraded site. We also tested differences in all monitored meteorological and soil variables and CO2 at 1.50 m belowground was the variable showing the greatest intersite difference, with ∼ 1000 ppm higher at the degraded site. Thus, we believe that subterranean ventilation of this vadose zone CO2, previously observed at both sites, partly drives the differences in C dynamics between them, especially during the dry season. It may be due to enhanced subsoil–atmosphere interconnectivity at the degraded site.

scholarly journals High Rates of Ecosytem Metabolism in Five Western Rivers

2011 ◽  
Vol 33 ◽  
pp. 115-118
Author(s):  
Robert Hall ◽  
Jennifer Tank ◽  
Michelle Baker ◽  
Emma Rosi-Marshall ◽  
Michael Grace ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Primary Production ◽  
Carbon Cycling ◽  
Carbon Balance ◽  
Carbon Fixation ◽  
Higher Plants ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Total Rate ◽  
Global Carbon

Primary production and respiration are core functions of river ecosystems that in part determine the carbon balance. Gross primary production (GPP) is the total rate of carbon fixation by autotrophs such as algae and higher plants and is equivalent to photosynthesis. Ecosystem respiration (ER) measures rate at which organic carbon is mineralized to CO2 by all organisms in an ecosystem. Together these fluxes can indicate the base of the food web to support animal production (Marcarelli et al. 2011), can predict the cycling of other elements (Hall and Tank 2003), and can link ecosystems to global carbon cycling (Cole et al. 2007).

scholarly journals Seasonal and annual variation of carbon fluxes in a young Siberian larch (<i>Larix sibirica</i>) plantation in Iceland

2009 ◽  
Vol 6 (4) ◽  
pp. 6601-6634 ◽  
Author(s):  
B. Bjarnadottir ◽  
B. D. Sigurdsson ◽  
A. Lindroth
Keyword(s):  
Carbon Balance ◽  
Climatic Factors ◽  
Ecosystem Respiration ◽  
Abiotic Factors ◽  
Gross Primary Production ◽  
Seasonal Pattern ◽  
Soil Water Potential ◽  
Siberian Larch ◽  
Frost Damage ◽  
Spring Frost

Abstract. This study reports 3-year measurements (2004–2006) of net ecosystem exchange (NEE) over a 12–14 year old Siberian larch forest in Iceland established on previously grazed heath land pasture that had been site-prepared prior to planting. The study evaluated interannual and seasonal variation of NEE and its component fluxes, gross primary production (GPP) and ecosystem respiration (Re), with the aim to clarify how climatic factors controlled the site's carbon balance. The young plantation acted as a relatively strong sink for CO2 during all of the three years, with a net sequestration of −375, −566 and −245 g CO2 m−2 for years 2004, 2005 and 2006, respectively. The annual carbon balance was strongly influenced by climatic factors leading to a high inter-annual variability in NEE. This variation was more related to variation in carbon efflux (Re) than carbon uptake (GPP). The abiotic factors that showed the strongest correlation to Re were air temperature during the growing season and soil water potential. The GPP mostly followed the seasonal pattern in irradiance, except in 2005, when the plantation experienced severe spring frost damage that set the GPP back to zero. It was not expected that the rather slow-growing Siberian larch plantation would be such a strong sink for atmospheric CO2 only twelve years after site preparation and afforestation.

scholarly journals Patterns of Arctic Tundra Greenness Based on Spatially Downscaled Solar-Induced Fluorescence

2019 ◽  
Vol 11 (12) ◽  
pp. 1460 ◽  
Author(s):  
Dongjie Fu ◽  
Fenzhen Su ◽  
Juan Wang ◽  
Yijie Sui
Keyword(s):  
Satellite Remote Sensing ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Gross Primary Production ◽  
Remote Sensing Data ◽  
Arctic Region ◽  
Arctic Tundra ◽  
The Arctic ◽  
Global Inventory ◽  
The Arctic Region

A general greening trend in the Arctic tundra biome has been indicated by satellite remote sensing data over recent decades. However, since 2011, there have been signs of browning trends in many parts of the region. Previous research on tundra greenness across the Arctic region has relied on the satellite-derived normalized difference vegetation index (NDVI). In this research, we initially used spatially downscaled solar-induced fluorescence (SIF) data to analyze the spatiotemporal variation of Arctic tundra greenness (2007–2013). The results derived from the SIF data were also compared with those from two NDVIs (the Global Inventory Modeling and Mapping Studies NDVI3g and MOD13Q1 NDVI), and the eddy-covariance (EC) observed gross primary production (GPP). It was found that most parts of the Arctic tundra below 75° N were browning (–0.0098 mW/m2/sr/nm/year, where sr is steradian and nm is nanometer) using SIF, whereas spatially and temporally heterogeneous trends (greening or browning) were obtained based on the two NDVI products. This research has further demonstrated that SIF data can provide an alternative direct proxy for Arctic tundra greenness.

scholarly journals Observed and modelled ecosystem respiration and gross primary production of a grassland in southwestern France

2010 ◽  
Vol 7 (1) ◽  
pp. 429-462 ◽  
Author(s):  
C. Albergel ◽  
J.-C. Calvet ◽  
A.-L. Gibelin ◽  
S. Lafont ◽  
J.-L. Roujean ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Primary Production ◽  
Root Zone ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Net Ecosystem Exchange ◽  
Co2 Flux ◽  
Single Equation ◽  
Complex Model ◽  
Area Index

Abstract. In this work, a simple representation of the soil moisture effect on the ecosystem respiration is implemented into the A-gs version of the Interactions between Soil, Biosphere, and Atmosphere (ISBA) model. It results in an improvement of the modelled CO2 flux over a grassland, in southwestern France. The former temperature-only dependent respiration formulation used in ISBA-A-gs is not able to model the limitation of the respiration under dry conditions. In addition to soil moisture and soil temperature, the only parameter required in this formulation is the ecosystem respiration parameter Re25. It can be estimated by the mean of eddy covariance measurements of turbulent nighttime CO2 flux (i.e. ecosystem respiration). The resulting correlation between observed and modelled net ecosystem exchange is r2=0.63 with a bias of −2.18 μmol m−2 s−1. It is shown that when CO2 observations are not available, it is possible to use a more complex model, able to represent the heterotrophic respiration and all the components of the autotrophic respiration, to estimate Re25 with similar results. The modelled ecosystem respiration estimates are provided by the Carbon Cycle (CC) version of ISBA (ISBA-CC). ISBA-CC is a version of ISBA able to simulate all the respiration components whereas ISBA-A-gs uses a single equation for ecosystem respiration. ISBA-A-gs is easier to handle and more convenient than ISBA-CC for practical use in atmospheric or hydrological models. Surface water and energy flux observations as well as gross primary production (GPP) estimates are compared with model outputs. The dependence of GPP to air temperature is investigated. The observed GPP is less sensitive to temperature than the modelled GPP. Finally, the simulations of the ISBA-A-gs model are analysed over a seven year period (2001–2007). Modelled soil moisture and leaf area index (LAI) are confronted with the observed root-zone soil moisture content (m3 m−3), and with LAI estimates derived from surface reflectance measurements.

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 Ecosystem CO2 flux rates in relation to vegetation type and age of Leymus arenarius dunes on Surtsey

2015 ◽  
Vol 13 ◽  
pp. 9-15
Author(s):  
Bjarni D. Sigurdsson ◽  
Guðrún Stefánsdóttir
Keyword(s):  
Soil Respiration ◽  
Primary Succession ◽  
Ecosystem Respiration ◽  
Vegetation Type ◽  
Co2 Flux ◽  
Surface Cover ◽  
The Past ◽  
Belowground Processes ◽  
Initial Soil ◽  
Leymus Arenarius

The primary succession on the 50 year old volcanic island of Surtsey, Iceland, has been intensively studied. Initial soil development and other belowground processes are important drivers of primary succession but frequently overseen. A Leymus arenarius and Honckenya peploides dominated plant community has formed a relatively stable successional sere on the island, where external inputs of nutrients remain low. These plants have had a stable <10% aboveground surface cover during the past 20 years, but less is known about their belowground development. We investigated the organic matter (carbon) output and input processes (soil respiration, ecosystem respiration and photosynthesis) of the community and how they were affected by soil temperature, soil water content, vegetation and age of L. arenarius dunes. We found that both soil respiration and root stocks have increased substantially from 1987, when an earlier study was conducted. The same pattern was found when different aged L. arenarius dunes were studied. L. arenarius had a stronger effect on the soil respiration fluxes than its surface cover might indicate, through its much higher photosynthesis rates than H. peploides. The study furthermore illustrated how water stress may temporally limit belowground processes in this coastal community.

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