scholarly journals Earlier Snowmelt May Lead to Late Season Declines in Plant Productivity and Carbon Sequestration in Arctic Tundra Ecosystems

2021 ◽  
Author(s):  
Donatella Zona ◽  
Peter Lafleur ◽  
Koen Hufkens ◽  
Barbara Bailey ◽  
Beniamino Gioli ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Carbon Balance ◽  
Co2 Sequestration ◽  
Growing Season ◽  
The Arctic ◽  
Environmental Drivers ◽  
Soil Hydrology ◽  
Tundra Vegetation ◽  
The Impact ◽  
Tundra Ecosystems

Abstract Arctic warming is affecting snow cover and soil hydrology, with consequences for carbon sequestration in tundra ecosystems. The scarcity of observations in the Arctic has limited our understanding of the impact of covarying environmental drivers on the carbon balance of tundra ecosystems. In this study, we address some of these uncertainties through a novel record of 119 site-years of summer data from eddy covariance towers representing dominant tundra vegetation types located on continuous permafrost in the Arctic.Here we found that earlier snowmelt was associated with more net CO2 sequestration and higher gross primary productivity (GPP) only in June and July, but with lower net carbon sequestration and lower GPP in August. Although higher evapotranspiration (ET) can result in soil drying with the progression of the summer, we did not find significantly lower soil moisture with earlier snowmelt, nor evidence for a water stress that affected GPP in the peak and late growing season. Our results suggest that climate change and the associated increased length in the growing season might not benefit these northern tundra ecosystems if they are not able to continue sequestering CO2 later in the season.

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.

The role of soil characteristics on measured and modelled carbon dioxide and energy fluxes for Arctic dwarf shrub tundra sites

2020 ◽  
Author(s):  
Gesa Meyer ◽  
Elyn Humphreys ◽  
Joe Melton ◽  
Peter Lafleur ◽  
Philip Marsh ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Growing Season ◽  
Cold Season ◽  
Soil Characteristics ◽  
Heat Fluxes ◽  
Dwarf Shrub ◽  
The Arctic ◽  
Sensible Heat ◽  
Shrub Tundra ◽  
Tundra Ecosystems

<p>Four years of growing season eddy covariance measurements of net carbon dioxide (CO<sub>2</sub>) and energy fluxes were used to examine the similarities/differences in surface-atmosphere interactions at two dwarf shrub tundra sites within Canada’s Southern Arctic ecozone, separated by approximately 1000 km. Both sites, Trail Valley Creek (TVC) and Daring Lake (DL1), are characterised by similar climate (with some differences in radiation due to latitudinal differences), vegetation composition and structure, and are underlain by continuous permafrost, but differ in their soil characteristics. Total atmospheric heating (the sum of latent and sensible heat fluxes) was similar at the two sites. However, at DL1, where the surface organic layer was thinner and mineral soil coarser in texture, latent heat fluxes were greater, sensible heat fluxes were lower, soils were warmer and the active layer thicker. At TVC, cooler soils likely kept ecosystem respiration relatively low despite similar total growing season productivity. As a result, the 4-year mean net growing season ecosystem CO<sub>2 </sub>uptake (May 1 - September 30) was almost twice as large at TVC (64 ± 19 g C m<sup>-2</sup>) compared to DL1 (33 ± 11 g C m<sup>-2</sup>). These results highlight that soil and thaw characteristics are important to understand variability in surface-atmosphere interactions among tundra ecosystems.</p><p>As recent studies have shown, winter fluxes play an important role in the annual CO<sub>2</sub> balance of Arctic tundra ecosystems. However, flux measurements were not available at TVC and DL1 during the cold season. Thus, the process-based ecosystem model CLASSIC (the Canadian Land Surface Scheme including biogeochemical Cycles, formerly CLASS-CTEM) was used to simulate year-round fluxes. In order to represent the Arctic shrub tundra better, shrub and sedge plant functional types were included in CLASSIC and results were evaluated using measurements at DL1. Preliminary results indicate that cold season CO<sub>2</sub> losses are substantial and may exceed the growing season CO<sub>2</sub> uptake at DL1 during 2010-2017. The joint use of observations and models is valuable in order to better constrain the Arctic CO<sub>2</sub> balance.  </p>

scholarly journals Carbon balance of a grazed savanna grassland ecosystem in South Africa

2016 ◽  
Author(s):  
Matti Räsänen ◽  
Mika Aurela ◽  
Ville Vakkari ◽  
Johan P. Beukes ◽  
Pieter G. Van Zyl ◽  
...  
Keyword(s):  
South Africa ◽  
Carbon Dioxide ◽  
Carbon Balance ◽  
Ecosystem Respiration ◽  
Functional Relation ◽  
Growing Season ◽  
Tree Cover ◽  
Environmental Drivers ◽  
Terrestrial Vegetation ◽  
Yearly Variation

Abstract. Tropical savannas and grasslands are estimated to contribute significantly to the total primary production of all terrestrial vegetation. Large parts of African savannas and grasslands are used for agriculture and cattle grazing, but the carbon flux data available from these areas is limited. This study explores carbon dioxide fluxes measured with the eddy covariance method for three years at a grazed savanna grassland in Welgegund, South Africa. The tree cover around the measurement site, grazed by cattle and sheep, was around 15 %. The night-time respiration was not significantly dependent on either soil moisture or soil temperature on a weekly temporal scale, whereas on an annual time scale higher respiration rates were observed when soil temperatures were higher. The yearly carbon dioxide balances of the growing seasons 2010–11, 2011–12 and 2012–13 were −85, 67 and 139 g C m−2 yr−1, respectively. The yearly variation was largely determined by the changes in the early wet season fluxes (September to November) and in the mid-growing season fluxes (December to January). Early rainfall enhanced the respiratory capacity of the ecosystem throughout the year, whereas during the mid-growing season high rainfall resulted in high carbon uptake. This study underlines the difficulty in establishing a functional relation between the total ecosystem respiration and the environmental drivers in savanna ecosystems. Furthermore, the high inter-annual variation of carbon balance in savanna ecosystems is difficult to relate to environmental drivers.

scholarly journals Underestimated effects of low temperature during early growing season on carbon sequestration of a subtropical coniferous plantation

2011 ◽  
Vol 8 (6) ◽  
pp. 1667-1678 ◽  
Author(s):  
W.-J. Zhang ◽  
H.-M. Wang ◽  
F.-T. Yang ◽  
Y.-H. Yi ◽  
X.-F. Wen ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Air Temperature ◽  
Growing Season ◽  
Carbon Uptake ◽  
Summer Drought ◽  
Eddy Flux ◽  
Season Length ◽  
Growing Season Length ◽  
Coniferous Plantation ◽  
The Impact

Abstract. The impact of air temperature in early growing season on the carbon sequestration of a subtropical coniferous plantation was discussed through analyzing the eddy flux observations at Qianyanzhou (QYZ) site in southern China from 2003 to 2008. This site experienced two cold early growing seasons (with temperature anomalies of 2–5 °C) in 2005 and 2008, and a severe summer drought in 2003. Results indicated that the low air temperature from January to March was the major factor controlling the inter-annual variations in net carbon uptake at this site, rather than the previously thought summer drought. The accumulative air temperature from January to February showed high correlation (R2=0.970, p<0.001) with the annual net ecosystem production (NEP). This was due to the controls of early-month temperature on the plant phenology developing and the growing season length at this subtropical site. The cold spring greatly shortened the growing season length and therefore reduced the carbon uptake period. The eddy flux observations showed a carbon loss of 4.04 g C m−2 per growing-season day at this coniferous forest site. On the other hand, the summer drought also reduced the net carbon uptake strength because the photosynthesis was more sensitive to water deficit stress than the ecosystem respiration. However, the impact of summer drought occurred within a relatively shorter period and the carbon sequestration went back to the normal level once the drought was relieved.

scholarly journals Climate-driven changes in functional biogeography of Arctic marine fish communities

2017 ◽  
Vol 114 (46) ◽  
pp. 12202-12207 ◽  
Author(s):  
André Frainer ◽  
Raul Primicerio ◽  
Susanne Kortsch ◽  
Magnus Aune ◽  
Andrey V. Dolgov ◽  
...  
Keyword(s):  
Climate Change ◽  
Functional Traits ◽  
Marine Environment ◽  
Ecosystem Functioning ◽  
Barents Sea ◽  
Spatial Scales ◽  
Fish Communities ◽  
The Arctic ◽  
Environmental Drivers ◽  
The Impact

Climate change triggers poleward shifts in species distribution leading to changes in biogeography. In the marine environment, fish respond quickly to warming, causing community-wide reorganizations, which result in profound changes in ecosystem functioning. Functional biogeography provides a framework to address how ecosystem functioning may be affected by climate change over large spatial scales. However, there are few studies on functional biogeography in the marine environment, and none in the Arctic, where climate-driven changes are most rapid and extensive. We investigated the impact of climate warming on the functional biogeography of the Barents Sea, which is characterized by a sharp zoogeographic divide separating boreal from Arctic species. Our unique dataset covered 52 fish species, 15 functional traits, and 3,660 stations sampled during the recent warming period. We found that the functional traits characterizing Arctic fish communities, mainly composed of small-sized bottom-dwelling benthivores, are being rapidly replaced by traits of incoming boreal species, particularly the larger, longer lived, and more piscivorous species. The changes in functional traits detected in the Arctic can be predicted based on the characteristics of species expected to undergo quick poleward shifts in response to warming. These are the large, generalist, motile species, such as cod and haddock. We show how functional biogeography can provide important insights into the relationship between species composition, diversity, ecosystem functioning, and environmental drivers. This represents invaluable knowledge in a period when communities and ecosystems experience rapid climate-driven changes across biogeographical regions.

Responses to simulated grazing and browsing of vegetation available to caribou in the Arctic

1994 ◽  
Vol 72 (8) ◽  
pp. 1426-1435 ◽  
Author(s):  
Jean-Pierre Ouellet ◽  
Stan Boutin ◽  
Doug C. Heard
Keyword(s):  
Chemical Composition ◽  
Net Primary Production ◽  
Growing Season ◽  
The Arctic ◽  
Wet Meadow ◽  
Net Production ◽  
Total Nonstructural Carbohydrates ◽  
Simulated Grazing ◽  
High Degree ◽  
The Impact

We investigated the consequences of simulated grazing and browsing on net primary production and chemical composition (nutrients, fiber, and total nonstructural carbohydrates) of some plant types available to caribou on Southampton Island, Northwest Territories, Canada. Clipping experiments were conducted in three large exclosures (22 × 22 m) on one deciduous (Salix lanata), one evergreen (Cassiope tetragona), and one semi-evergreen (Dryas integrifolia) shrub species and two types of sedges (Carex scirpoidea and wet-meadow sedges). The impact of various clipping regimes was analyzed in the growing season during which the treatments were applied and at the end of the following growing season. Clipping, for the most part, reduced plant net production. Responses differed among and within plant types according to the timing and intensity of clipping. In some cases maximum net production of plants was not restored during the recovery year, although grazing and browsing pressure was lifted. Clipping modified the chemical composition of S. lanata, D. integrifolia, and the two types of sedges investigated. In clipped sedges, nitrogen, magnesium, potassium, and phosphorus levels in regrowth were above the maximum obtained from controls at any point during the growing season. These chemical changes possibly enhanced the quality of these plants as food for herbivores. Because plant types that showed a high degree of compensatory growth also showed an increase in quality following clipping, herbivores might benefit if they reselect these plants over the course of the growing season. Growth of S. lanata is negatively affected by clipping and represents an important component of the caribou's summer diet, therefore willows are expected to decrease in abundance as the caribou population increases. The decrease in abundance of deciduous shrubs may have important consequences for the caribou's range use and population dynamics.

scholarly journals Impact of vessel traffic on the home ranges and movement of shorthorn sculpin (Myoxocephalus scorpius) in the nearshore environment of the high Arctic

2018 ◽  
Vol 75 (12) ◽  
pp. 2390-2400 ◽  
Author(s):  
Silviya V. Ivanova ◽  
Steven T. Kessel ◽  
Justin Landry ◽  
Caitlin O’Neill ◽  
Montana F. McLean ◽  
...  
Keyword(s):  
Acoustic Telemetry ◽  
Open Water ◽  
High Arctic ◽  
The Arctic ◽  
Environmental Drivers ◽  
Home Ranges ◽  
Shorthorn Sculpin ◽  
Arctic Fish ◽  
Myoxocephalus Scorpius ◽  
The Impact

Sea ice reduction in the Arctic is allowing for increased vessel traffic and activity. Vessel noise is a known anthropogenic disturbance, but its effects on Arctic fish are largely unknown. Using acoustic telemetry — Vemco positioning system — we quantified the home ranges and fine-scale movement types (MT) of shorthorn sculpin (Myoxocephalus scorpius), a common benthic Arctic fish, in response to vessels and environmental drivers during open water over 3 years (2012–2014). Low overlap of core home ranges (50%) for all years and a change of overall MT proportions (significant in 2012 only) were observed when vessels were present compared with absent. However, changes in MTs associated with vessel presence were not consistent between years. Photoperiod was the only environmental driver that influenced (R2 = 0.32) MTs of sculpin. This is the first study of vessel impacts on Arctic fish using acoustic telemetry and demonstrates that individuals alter their behavior and home ranges when vessels are present. Given increasing vessel traffic in the Arctic, additional study on the impact of vessels on these ecosystems is warranted.

scholarly journals Response of vegetation and carbon fluxes to brown lemming herbivory in Northern Alaska

2021 ◽  
Author(s):  
Jessica Plein ◽  
Rulon W. Clark ◽  
Kyle A. Arndt ◽  
Walter C. Oechel ◽  
Douglas Stow ◽  
...  
Keyword(s):  
Carbon Fluxes ◽  
Arctic Tundra ◽  
The Arctic ◽  
Co2 Uptake ◽  
Co2 Fluxes ◽  
Environmental Controls ◽  
Global Rate ◽  
Tundra Ecosystem ◽  
The Impact ◽  
Tundra Ecosystems

Abstract. The Arctic is warming at double the average global rate, affecting the carbon cycle of tundra ecosystems. Most research on carbon fluxes from Arctic tundra ecosystems has focused on abiotic environmental controls (e.g. temperature, rainfall, or radiation). However, Arctic tundra vegetation, and therefore the carbon balance of these ecosystems, can be substantially impacted by herbivory. In this study we tested how vegetation consumption by brown lemmings (Lemmus trimucronatus) can impact carbon exchange of a wet-sedge tundra ecosystem near Utqiaġvik, Alaska during the summer, and the recovery of vegetation during a following summer. We placed brown lemmings in individual enclosure plots and tested the impact of lemmings’ herbivory on carbon dioxide (CO2) and methane (CH4) fluxes and the normalized difference vegetation index (NDVI) immediately after lemming removal and during the following growing season. During the first summer of the experiment, lemmings’ herbivory reduced plant biomass (as shown by the decrease in the NDVI) and decreased CO2 uptake, while not significantly impacting CH4 emissions. Methane emissions were likely not significantly affected due to CH4 being produced deeper in the soil and escaping from the stem bases of the vascular plants. The summer following the lemming treatments, NDVI and CO2 fluxes returned to magnitudes similar to those observed before the start of the experiment, suggesting recovery of the vegetation, and a transitory nature of the impact of lemming herbivory. Overall, lemming herbivory has short-term but substantial effects on carbon sequestration by vegetation and might contribute to the considerable interannual variability in CO2 fluxes from tundra ecosystems.

scholarly journals Underestimated effects of low temperature during early growing season on carbon sequestration of a subtropical coniferous plantation

2011 ◽  
Vol 8 (1) ◽  
pp. 1411-1444
Author(s):  
W.-J. Zhang ◽  
H.-M. Wang ◽  
F.-T. Yang ◽  
Y.-H. Yi ◽  
X.-F. Wen ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Air Temperature ◽  
Growing Season ◽  
Carbon Uptake ◽  
Summer Drought ◽  
Eddy Flux ◽  
Season Length ◽  
Growing Season Length ◽  
Coniferous Plantation ◽  
The Impact

Abstract. The impact of air temperature in early months on the carbon sequestration of a subtropical coniferous plantation was discussed by analyzing the eddy flux observations at Qianyanzhou (QYZ) site located in southern China from 2003 to 2008. This site experienced two cold early growing seasons (with temperature anomalies of 2–5° C) in 2005 and 2008, and also a severe summer drought in 2003. Results indicated that the low air temperature from January to March was the major factor controlling the inter-annual variations in net carbon uptake at this site, rather than the previously thought summer drought. The accumulative air temperature from January to February showed high correlation (R2 = 0.970, p < 0.001) with the annual net ecosystem production (NEP). This was due to the controls of early-months temperature on the plant phenology developing and the growing season length at this subtropical site. The cold spring greatly shortened the growing season length and therefore reduced the carbon uptake period. The eddy flux observations showed a carbon loss of 4.04 g C m−2 per growing-season day at this coniferous forest site. On the other hand, the summer drought also reduced the net carbon uptake strength because the photosynthesis was more sensitive to water deficit stress than the ecosystem respiration. However, the impact of summer drought occurred within a relatively shorter period and the carbon sequestration went back to the normal level once the drought was relieved.

Consideration of Geopolitical Challenges within the Analysis of Geoenvironmental Risks for Oil and Gas Development of the Russian Arctic

2019 ◽  
Vol 16 (6) ◽  
pp. 50-59
Author(s):  
O. P. Trubitsina ◽  
V. N. Bashkin
Keyword(s):  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Optimal Operation ◽  
The Arctic ◽  
Stage Model ◽  
Oil And Gas Development ◽  
Gas Industry ◽  
The Impact ◽  
Further Development ◽  
Geopolitical Risks

The article is devoted to the consideration of geopolitical challenges for the analysis of geoenvironmental risks (GERs) in the hydrocarbon development of the Arctic territory. Geopolitical risks (GPRs), like GERs, can be transformed into opposite external environment factors of oil and gas industry facilities in the form of additional opportunities or threats, which the authors identify in detail for each type of risk. This is necessary for further development of methodological base of expert methods for GER management in the context of the implementational proposed two-stage model of the GER analysis taking to account GPR for the improvement of effectiveness making decisions to ensure optimal operation of the facility oil and gas industry and minimize the impact on the environment in the geopolitical conditions of the Arctic.The authors declare no conflict of interest

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