scholarly journals Spatial and temporal patterns of biophysical variables and their influence on CO2 flux in a high arctic wetland

2021 ◽  
Author(s):  
Sarah Luce
Keyword(s):  
Climate Change ◽  
Carbon Sources ◽  
Co2 Flux ◽  
High Arctic ◽  
Co2 Exchange ◽  
Co2 Production ◽  
Co2 Uptake ◽  
Spatial And Temporal Patterns ◽  
Carbon Cycles ◽  
Arctic Wetlands

Arctic wetlands have been globally important carbon reservoirs throughout the past but climate change is threatening to shift their status to carbon sources. Increasing Arctic temperatures are depleting perennial snowpacks these wetlands depend upon as their hydrological inputs which is altering their environmental conditions and carbon cycles. The objective of this study is to investigate how the physical conditions of Arctic wetlands will be altered by climate change and what influence these changes will have on CO2 exchange. High spatial and temporal resolution biophysical data from a high Arctic wetland, collected over the growing season of 2015, was used for this analysis. The results from this study indicate that the wetland is at risk of thawing and drying out under a warmer climate regime. CO2 emissions were found to increase most significantly with increased air temperatures, while CO2 uptake increased with increases in solar radiation and soil moisture. Combined, these results suggest that CO2 production in the soil will increase while CO2 uptake will decrease in Arctic wetlands as climate change continues.

scholarly journals Spatial and temporal patterns of biophysical variables and their influence on CO2 flux in a high arctic wetland

2021 ◽  
Author(s):  
Sarah Luce
Keyword(s):  
Climate Change ◽  
Carbon Sources ◽  
Co2 Flux ◽  
High Arctic ◽  
Co2 Exchange ◽  
Co2 Production ◽  
Co2 Uptake ◽  
Spatial And Temporal Patterns ◽  
Carbon Cycles ◽  
Arctic Wetlands

Arctic wetlands have been globally important carbon reservoirs throughout the past but climate change is threatening to shift their status to carbon sources. Increasing Arctic temperatures are depleting perennial snowpacks these wetlands depend upon as their hydrological inputs which is altering their environmental conditions and carbon cycles. The objective of this study is to investigate how the physical conditions of Arctic wetlands will be altered by climate change and what influence these changes will have on CO2 exchange. High spatial and temporal resolution biophysical data from a high Arctic wetland, collected over the growing season of 2015, was used for this analysis. The results from this study indicate that the wetland is at risk of thawing and drying out under a warmer climate regime. CO2 emissions were found to increase most significantly with increased air temperatures, while CO2 uptake increased with increases in solar radiation and soil moisture. Combined, these results suggest that CO2 production in the soil will increase while CO2 uptake will decrease in Arctic wetlands as climate change continues.

The Effects of Predicted Soil Moisture and Temperature Increase on CO2 Exchange within a High Arctic Ecosystem

2018 ◽  
Author(s):  
Sarah Jackson
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Co2 Flux ◽  
High Arctic ◽  
Co2 Exchange ◽  
The Arctic ◽  
Co2 Production ◽  
Arctic Ecosystems ◽  
Arctic Regions ◽  
Snow Fences

With 2014 being the warmest year on record and 10 of the warmest years occurring after 1997, it is essential to understand the effects of this warming on CO2 exchange. It was also discovered that much of this warming is focused in the Arctic regions, which are sensitive to changes in temperature (Cole & McCarthy, 2015). My research examines the effects of enhanced snowfall and soil temperature on the exchange of CO2 between the land and the atmosphere in a high arctic environment. The research is taking place at Cape Bounty Arctic Watershed Observatory (CBAWO) on Melville Island, Nunavut as part of the International Tundra Experiment (ITEX). The goal of ITEX is to better understand the effects of increased summer temperature and increased snowfall on arctic ecosystems. This is a full factorial experiment including treatments varying precipitation (and likely soil moisture), soil temperature, moisture and temperature together, and a control that is at ambient soil moisture and temperature. Snow fences are used to enhance precipitation, while open-topped transparent chambers are used to increase soil temperature. In a companion lab experiment, I look at the effects of different soil moisture levels and temperatures on soil CO2 production in a more controlled environment. Two temperatures, two moisture levels, and eight replicates of each will be established in sealed incubation chambers, and soils will be incubated for 33 days. Presently a significant relationship has been found between soil moisture and CO2 flux within the field experiment.

scholarly journals Patterns of longer-term climate change effects on CO<sub>2</sub> efflux from biocrusted soils differ from those observed in the short term

2018 ◽  
Vol 15 (14) ◽  
pp. 4561-4573 ◽  
Author(s):  
Anthony Darrouzet-Nardi ◽  
Sasha C. Reed ◽  
Edmund E. Grote ◽  
Jayne Belnap
Keyword(s):  
Climate Change ◽  
Monsoon Season ◽  
Vascular Plant ◽  
Precipitation Amount ◽  
Co2 Flux ◽  
Co2 Exchange ◽  
Plant Responses ◽  
Co2 Efflux ◽  
Climate Change Effects ◽  
Altered Precipitation

Abstract. Biological soil crusts (biocrusts) are predicted to be sensitive to the increased temperature and altered precipitation associated with climate change. We assessed the effects of these factors on soil carbon dioxide (CO2) balance in biocrusted soils using a sequence of manipulations over a 9-year period. We warmed biocrusted soils by 2 and, later, by 4 ∘C to better capture updated forecasts of future temperature at a site on the Colorado Plateau, USA. We also watered soils to alter monsoon-season precipitation amount and frequency and had plots that received both warming and altered precipitation treatments. Within treatment plots, we used 20 automated flux chambers to monitor net soil exchange (NSE) of CO2 hourly, first in 2006–2007 and then again in 2013–2014, for a total of 39 months. Net CO2 efflux from biocrusted soils in the warming treatment increased a year after the experiment began (2006–2007). However, after 9 years and even greater warming (4 ∘C), results were more mixed, with a reversal of the increase in 2013 (i.e., controls showed higher net CO2 efflux than treatment plots) and with similarly high rates in all treatments during 2014, a wet year. Over the longer term, we saw evidence of reduced photosynthetic capacity of the biocrusts in response to both the temperature and altered precipitation treatments. Patterns in biocrusted soil CO2 exchange under experimentally altered climate suggest that (1) warming stimulation of CO2 efflux was diminished later in the experiment, even in the face of greater warming; and (2) treatment effects on CO2 flux patterns were likely driven by changes in biocrust species composition and by changes in root respiration due to vascular plant responses.

scholarly journals An empirical model simulating long-term diurnal CO<sub>2</sub> flux for diverse vegetation types

2008 ◽  
Vol 5 (5) ◽  
pp. 4001-4034
Author(s):  
M. Saito ◽  
S. Maksyutov ◽  
R. Hirata ◽  
A. D. Richardson
Keyword(s):  
Empirical Model ◽  
Vapor Pressure Deficit ◽  
Ecosystem Respiration ◽  
Co2 Flux ◽  
Co2 Exchange ◽  
Physiological Parameters ◽  
Co2 Uptake ◽  
Diurnal Variability ◽  
Terrestrial Biomes

Abstract. We present an empirical model for the estimation of diurnal variability in net ecosystem CO2 exchange (NEE). The model is based on the use of a nonrectangular hyperbola for photosynthetic response of canopy and was constructed by using a dataset obtained from the AmeriFlux network and containing continuous eddy covariance CO2 flux from 26 ecosystems over seven biomes. The model uses simplified empirical expression of seasonal variability in biome-specific physiological parameters with air temperature, vapor pressure deficit, and precipitation. The physiological parameters of maximum CO2 uptake rate by the canopy and ecosystem respiration had biome-specific responses to environmental variables. The estimated physiological parameters had reasonable magnitudes and seasonal variation and gave reasonable timing of the beginning and end of the growing season over various biomes, but they were less satisfactory for disturbed grassland and savanna than for forests. Comparison with observational data revealed that the diurnal cycle of NEE was generally well predicted all year round by the model. The model gave satisfactory results even for tundra, which had very small amplitudes of NEE variability. These results suggest that this model with biome-specific parameters will be applicable to numerous terrestrial biomes, particularly forest ones.

scholarly journals CO<sub>2</sub> flux determination by closed-chamber methods can be seriously biased by inappropriate application of linear regression

2007 ◽  
Vol 4 (6) ◽  
pp. 1005-1025 ◽  
Author(s):  
L. Kutzbach ◽  
J. Schneider ◽  
T. Sachs ◽  
M. Giebels ◽  
H. Nykänen ◽  
...  
Keyword(s):  
Linear Regression ◽  
Nonlinear Regression ◽  
Co2 Flux ◽  
Exponential Model ◽  
Co2 Uptake ◽  
Co2 Fluxes ◽  
Closed Chamber ◽  
Exponential Regression ◽  
Closure Time ◽  
Over Time

Abstract. Closed (non-steady state) chambers are widely used for quantifying carbon dioxide (CO2) fluxes between soils or low-stature canopies and the atmosphere. It is well recognised that covering a soil or vegetation by a closed chamber inherently disturbs the natural CO2 fluxes by altering the concentration gradients between the soil, the vegetation and the overlying air. Thus, the driving factors of CO2 fluxes are not constant during the closed chamber experiment, and no linear increase or decrease of CO2 concentration over time within the chamber headspace can be expected. Nevertheless, linear regression has been applied for calculating CO2 fluxes in many recent, partly influential, studies. This approach has been justified by keeping the closure time short and assuming the concentration change over time to be in the linear range. Here, we test if the application of linear regression is really appropriate for estimating CO2 fluxes using closed chambers over short closure times and if the application of nonlinear regression is necessary. We developed a nonlinear exponential regression model from diffusion and photosynthesis theory. This exponential model was tested with four different datasets of CO2 flux measurements (total number: 1764) conducted at three peatlands sites in Finland and a tundra site in Siberia. Thorough analyses of residuals demonstrated that linear regression was frequently not appropriate for the determination of CO2 fluxes by closed-chamber methods, even if closure times were kept short. The developed exponential model was well suited for nonlinear regression of the concentration over time c(t) evolution in the chamber headspace and estimation of the initial CO2 fluxes at closure time for the majority of experiments. However, a rather large percentage of the exponential regression functions showed curvatures not consistent with the theoretical model which is considered to be caused by violations of the underlying model assumptions. Especially the effects of turbulence and pressure disturbances by the chamber deployment are suspected to have caused unexplainable curvatures. CO2 flux estimates by linear regression can be as low as 40% of the flux estimates of exponential regression for closure times of only two minutes. The degree of underestimation increased with increasing CO2 flux strength and was dependent on soil and vegetation conditions which can disturb not only the quantitative but also the qualitative evaluation of CO2 flux dynamics. The underestimation effect by linear regression was observed to be different for CO2 uptake and release situations which can lead to stronger bias in the daily, seasonal and annual CO2 balances than in the individual fluxes. To avoid serious bias of CO2 flux estimates based on closed chamber experiments, we suggest further tests using published datasets and recommend the use of nonlinear regression models for future closed chamber studies.

scholarly journals There is a silver lining: carbon footprint reduction by holding Preventive Cardiology conference 2020 virtually

2021 ◽  
Vol 28 (Supplement_1) ◽  
Author(s):  
T Batool ◽  
A Neven ◽  
Y Vanrompay ◽  
M Adnan ◽  
P Dendale
Keyword(s):  
Climate Change ◽  
Co2 Emissions ◽  
Carbon Footprint ◽  
Carbon Emission ◽  
Ghg Emissions ◽  
Air Travel ◽  
Co2 Production ◽  
Scientific Conference ◽  
Preventive Cardiology ◽  
Transport Modes

Abstract Funding Acknowledgements Type of funding sources: Other. Main funding source(s): Special Research Fund (BOF), Hasselt University Introduction The transportation sector is one of the major sectors influencing climate change, contributing around 16% of total Greenhouse gases (GHG) emissions. Aviation contributes to 12% of the transport related emissions. Among other climate change impacts, elevated heat exposure is associated with increased cardiac events and exposure to air pollution caused by GHG emissions has also well-known association with increased cardiovascular related morbidity and mortality. The global temperature rise should be restricted to less than 2 °C which requires keeping carbon emission (CO2) less than 2900 billion tonnes by the end of the 21st century. Assuming air travel a major contributing source to GHG, this study aims to raise the awareness about potential carbon emissions reduction due to air travel of international events like a scientific conference. Purpose Due to the global pandemic of COVID-19, the Preventive cardiology conference 2020 which was planned to be held at Malaga Spain, instead was held in virtual online way. This study aims to calculate the contribution of reduced CO2  emissions in tons due to ESC preventive cardiology conference 2020, which was then held online and air travel of the registered participants was avoided. Methods Anonymized participant registration information was used to determine the country and city of the 949 registered participants of the Preventive Cardiology conference 2020. It is assumed that participants would have travelled from the closest airports from their reported city locations to Malaga airport, Spain. At first, the closest city airports were determined using Google maps and flights information, then the flight emissions (direct and indirect CO2-equivalent emissions) per passenger for the given flight distances were calculated. The CO2 emissions (tons) were calculated for round trips in economy class from the participants of 68 nationalities (excluding 60 participants from Spain as they are assumed to take other modes of transport than airplane). Results In total, 1156.51 tons of CO2  emissions were saved by turning the physical conference into a virtual event. This emission amount is equivalent to the annual CO2 production of 108 people living in high-income countries. Conclusion The pandemic situation has forced us to rethink the necessity of trips by air and has shown us the feasibility of digitally organized events. The information from this study can add to the awareness about reduced amount of carbon emission due to air travel by organizing events in a virtual way when possible. Apart from only digitally organized events there are others options to reduce the carbon footprint of conferences such as limiting the number of physical attendees, encouraging the use of relatively sustainable transport modes for participants from nearby countries (e.g. international trains and use of active transport modes at conference venue etc.) and including CO2 emission offsetting costs.

scholarly journals Climate Change Drives Widespread and Rapid Thermokarst Development in Very Cold Permafrost in the Canadian High Arctic

2019 ◽  
Vol 46 (12) ◽  
pp. 6681-6689 ◽  
Author(s):  
Louise M. Farquharson ◽  
Vladimir E. Romanovsky ◽  
William L. Cable ◽  
Donald A. Walker ◽  
Steven V. Kokelj ◽  
...  
Keyword(s):  
Climate Change ◽  
High Arctic ◽  
Canadian High Arctic

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.

Carbon sources for lake food webs in the Canadian High Arctic and other regions of Arctic North America

Polar Biology ◽  
2010 ◽  
Vol 33 (8) ◽  
pp. 1111-1123 ◽  
Author(s):  
John Chételat ◽  
Louise Cloutier ◽  
Marc Amyot
Keyword(s):  
North America ◽  
Food Webs ◽  
Carbon Sources ◽  
High Arctic ◽  
Canadian High Arctic
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