scholarly journals The role of vegetation in the CO<sub>2</sub> flux from a tropical urban neighbourhood

2013 ◽  
Vol 13 (3) ◽  
pp. 7267-7310 ◽  
Author(s):  
E. Velasco ◽  
M. Roth ◽  
S. H. Tan ◽  
M. Quak ◽  
S. D. A. Nabarro ◽  
...  
Keyword(s):  
Anthropogenic Activities ◽  
Co2 Flux ◽  
Accurate Estimation ◽  
Urban Vegetation ◽  
Co2 Uptake ◽  
Co2 Fluxes ◽  
Activity Data ◽  
The Difference ◽  
Residential Neighbourhood

Abstract. Urban surfaces are usually net sources of CO2. Vegetation can potentially have an important role in reducing the CO2 emitted by anthropogenic activities in cities, particularly when vegetation is extensive and/or evergreen. Negative daytime CO2 fluxes, for example have been observed during the growing season at suburban sites characterized by abundant vegetation and low population density. A direct and accurate estimation of carbon uptake by urban vegetation is difficult due to the particular characteristics of the urban ecosystem and high variability in tree distribution and species. Here, we investigate the role of urban vegetation in the CO2 flux from a residential neighbourhood in Singapore using two different approaches. CO2 fluxes measured directly by eddy covariance are compared with emissions estimated from emissions factors and activity data. The latter includes contributions from vehicular traffic, household combustion, soil respiration and human breathing. The difference between estimated emissions and measured fluxes should approximate the biogenic flux. In addition, a tree survey was conducted to estimate the annual CO2 sequestration using allometric equations and an alternative model of the metabolic theory of ecology for tropical forests. Palm trees, banana plants and turfgrass were also included in the survey with their annual CO2 uptake obtained from published growth rates. Both approaches agree within 2% and suggest that vegetation captures 8% of the total emitted CO2 in the residential neighbourhood studied. A net uptake of 1.4 ton km−2 day−1 (510 ton km−2 yr−1 ) was estimated from the difference between the daily CO2 uptake by photosynthesis (3.95 ton km−2 ) and release by respiration (2.55 ton km−2). The study shows the importance of urban vegetation at the local scale for climate change mitigation in the tropics.

scholarly journals The role of vegetation in the CO2 flux from a tropical urban neighbourhood

2013 ◽  
Vol 13 (20) ◽  
pp. 10185-10202 ◽  
Author(s):  
E. Velasco ◽  
M. Roth ◽  
S. H. Tan ◽  
M. Quak ◽  
S. D. A. Nabarro ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Anthropogenic Activities ◽  
Co2 Flux ◽  
Accurate Estimation ◽  
Urban Vegetation ◽  
Co2 Uptake ◽  
Total Contribution ◽  
The Difference ◽  
Residential Neighbourhood

Abstract. Urban surfaces are usually net sources of CO2. Vegetation can potentially have an important role in reducing the CO2 emitted by anthropogenic activities in cities, particularly when vegetation is extensive and/or evergreen. A direct and accurate estimation of carbon uptake by urban vegetation is difficult due to the particular characteristics of the urban ecosystem and high variability in tree distribution and species. Here, we investigate the role of urban vegetation in the CO2 flux from a residential neighbourhood in Singapore using two different approaches. CO2 fluxes measured directly by eddy covariance are compared with emissions estimated from emissions factors and activity data. The latter includes contributions from vehicular traffic, household combustion, soil respiration and human breathing. The difference between estimated emissions and measured fluxes should approximate the flux associated with the aboveground vegetation. In addition, a tree survey was conducted to estimate the annual CO2 sequestration using allometric equations and an alternative model of the metabolic theory of ecology for tropical forests. Palm trees, banana plants and turfgrass were also included in the survey with their annual CO2 uptake obtained from published growth rates. Both approaches agree within 2% and suggest that vegetation sequesters 8% of the total emitted CO2 in the residential neighbourhood studied. An uptake of 1.4 ton km−2 day−1 (510 ton km−2 yr−1) was estimated as the difference between assimilation by photosynthesis minus the aboveground biomass respiration during daytime (4.0 ton km−2 day−1) and release by plant respiration at night (2.6 ton km−2 day−1). However, when soil respiration is added to the daily aboveground flux, the biogenic component becomes a net source amounting to 4% of the total CO2 flux and represents the total contribution of urban vegetation to the carbon flux to the atmosphere.

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 Prediction of photosynthesis in Scots pine ecosystems across Europe by a needle-level theory

2018 ◽  
Vol 18 (18) ◽  
pp. 13321-13328
Author(s):  
Pertti Hari ◽  
Steffen Noe ◽  
Sigrid Dengel ◽  
Jan Elbers ◽  
Bert Gielen ◽  
...  
Keyword(s):  
Scots Pine ◽  
Boreal Forests ◽  
Co2 Flux ◽  
Field Studies ◽  
Co2 Assimilation ◽  
Co2 Fluxes ◽  
New Era ◽  
Evergreen Forests ◽  
Transition Times

Abstract. Photosynthesis provides carbon for the synthesis of macromolecules to construct cells during growth. This is the basis for the key role of photosynthesis in the carbon dynamics of ecosystems and in the biogenic CO2 assimilation. The development of eddy-covariance (EC) measurements for ecosystem CO2 fluxes started a new era in the field studies of photosynthesis. However, the interpretation of the very variable CO2 fluxes in evergreen forests has been problematic especially in transition times such as the spring and autumn. We apply two theoretical needle-level equations that connect the variation in the light intensity, stomatal action and the annual metabolic cycle of photosynthesis. We then use these equations to predict the photosynthetic CO2 flux in five Scots pine stands located from the northern timberline to Central Europe. Our result has strong implications for our conceptual understanding of the effects of the global change on the processes in boreal forests, especially of the changes in the metabolic annual cycle of photosynthesis.

scholarly journals The Role of Vegetation in Reducing Anthropogenic CO2 in Bogor City

Agromet ◽  
2018 ◽  
Vol 32 (1) ◽  
pp. 42
Author(s):  
Ariesta Kusuma Wardhani ◽  
Bregas Budianto ◽  
Yon Sugiarto
Keyword(s):  
Air Temperature ◽  
Anthropogenic Activities ◽  
Daily Basis ◽  
Fuel Combustion ◽  
Photosynthesis Rate ◽  
Anova Test ◽  
The Difference ◽  
The City ◽  
One Way Anova

Vegetation has a role in reducing CO<sub>2</sub> from anthropogenic activities through photosynthesis. Fuel combustion is one of the activities that greatly contribute to CO<sub>2</sub> emissions. As a city with many destinations, the possibility of CO<sub>2</sub> emissions will increase in Bogor especially on holidays because of motorized vehicle from other cities. This research aims to determine the absorption capability of vegetation in Bogor City in reducing CO<sub>2</sub> emitted from fuel combustion. We analyzed CO<sub>2</sub> data for 2017 by day to obtain traffic levels in the city assuming that people mobility using vehicle was influenced by day. Then we separated CO<sub>2</sub> data into slow and fast photosynthesis rate based on air temperature. We determined the absorption capability of vegetation at daily basis by calculating the difference between the min and the max of CO<sub>2 </sub>concentration divided by the min of CO<sub>2</sub>. Our results showed that the lowest CO<sub>2</sub> level was in Sunday. On that day, the average air temperatur was high indicating the less CO<sub>2</sub> concentration. Our one-way Anova test confirmed this finding. The finding revealed that the absorption capability of vegetation to reduce anthropogenic CO<sub>2</sub> was still limited. To implement Bogor as green city, more vegetations and gardens are needed to balance an increased CO<sub>2</sub>.

scholarly journals Prediction of photosynthesis in Scots pine ecosystems across Europe by needle-level theory

2017 ◽  
Author(s):  
Pertti Hari ◽  
Steffen Noe ◽  
Sigrid Dengel ◽  
Jan Elbers ◽  
Bert Gielen ◽  
...  
Keyword(s):  
Scots Pine ◽  
Boreal Forests ◽  
Co2 Flux ◽  
Field Studies ◽  
Co2 Fluxes ◽  
New Era ◽  
Evergreen Forests ◽  
Eddy Covariance Measurements ◽  
Transition Times

Abstract. Photosynthesis provides carbon for the synthesis of macromolecules to construct cells during growth. This fact generates the key role of photosynthesis in the carbon dynamics of ecosystems (Taiz et al., 2015) and biogenic CO2 consumption. The development of eddy covariance measurements of ecosystem CO2 fluxes started a new era in the field studies of photosynthesis (Baldocchi et al., 2000). However, the interpretation of the very variable CO2 fluxes in evergreen forests has been problematic especially in transition times such as the spring and autumn. We apply two theoretical needle-level equations that connect the variation in the light intensity, stomatal action and the annual metabolic cycle with photosynthesis. We then show that these equations are able to predict quite precisely and accurately the photosynthetic CO2 flux between the atmosphere and different ecosystems in five Scots pine stands located from northern timberline to Central Europe. Our result has strong implications on the interpretation of the effects of the global change on the processes in boreal forests, especially of the changes in the metabolic annual cycle of photosynthesis.

scholarly journals Temporal and Spatial Characteristics of CO2 Flux in Plateau Urban Wetlands and Their Influencing Factors Based on Eddy Covariance Technique

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1176
Author(s):  
Yi Wu ◽  
Xufeng Mao ◽  
Zhifa Zhang ◽  
Wenjia Tang ◽  
Guangchao Cao ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Influencing Factors ◽  
Co2 Flux ◽  
Accurate Estimation ◽  
Co2 Uptake ◽  
Urban Wetlands ◽  
Spatial Characteristics ◽  
Urban Wetland ◽  
Temporal And Spatial ◽  
Temporal And Spatial Characteristics

Urban wetlands, an important part of the urban ecosystem, play an important role in regional carbon cycles and the carbon balance. To analyze the CO2 source and sink effects of plateau urban wetlands, based on the data measured by an eddy covariance instrument, the temporal and spatial characteristics of CO2 flux and their influencing factors in the urban wetland of Xining City in the Qinghai Province of China during a warm season (July to September 2020) were studied. The results show that: (1) On the daily scale, the CO2 flux exhibited an obvious “U”-type variation, characterized by strong uptake in the daytime and weak emission at night, with an average daily flux of −0.05 mg·m−2·s−1. The CO2 uptake peak of the wetland took place at 13:00 (−0.62 mg·m−2·s−1), and the emission peak occurred at 23:30 (0.34 mg·m−2·s−1); (2) on the monthly scale, the CO2 flux of the wetland in the study period showed a net uptake each month. The flux increased month by month, and the maximum value occurred in September (−142.82 g·m−2·month−1); (3) from a spatial point of view, the river area showed a weak CO2 uptake (−0.07 ± 0.03 mg·m−2·s−1), while the artificial wetland area showed a strong CO2 uptake (−0.14 ± 0.03 mg·m−2·s−1). The former was significantly lower than the latter (p < 0.01); (4) the regression analysis results show that the CO2 flux was significantly correlated with PAR, VPD, Tsoil, and SWC (p < 0.01). The relationships between the flux and PAR, Tsoil, and SWC were rectangular hyperbola (y = 0.2304 − 2 × 10−3x/(0.9037 + 0.0022x), R2 = 0.64), exponential (y = 0.046exp(0.091x), R2 = 0.88), and quadratic (y = −0.0041x2 + 0.1784x − 1.6946, R2 = 0.83), respectively. Under the joint action of various environmental factors, the urban wetland ecosystem in plateau displayed a strong carbon sink function in warm seasons. This study can establish a data scaffold for the accurate estimation of carbon budget of this type of ecosystem.

scholarly journals Uncertainty analysis of eddy covariance CO<sub>2</sub> flux measurements for different EC tower distances using an extended two-tower approach

2014 ◽  
Vol 11 (8) ◽  
pp. 11943-11983
Author(s):  
H. Post ◽  
H. J. Hendricks Franssen ◽  
A. Graf ◽  
M. Schmidt ◽  
H. Vereecken
Keyword(s):  
Eddy Covariance ◽  
Reference Method ◽  
Co2 Flux ◽  
Weather Conditions ◽  
Co2 Fluxes ◽  
Random Uncertainty ◽  
Extended Approach ◽  
Uncertainty Estimates ◽  
Flux Measurements

Abstract. The use of eddy covariance CO2 flux measurements in data assimilation and other applications requires an estimate of the random uncertainty. In previous studies, the two-tower approach has yielded robust uncertainty estimates, but care must be taken to meet the often competing requirements of statistical independence (non-overlapping footprints) and ecosystem homogeneity when choosing an appropriate tower distance. The role of the tower distance was investigated with help of a roving station separated between 8 m and 34 km from a permanent EC grassland station. Random uncertainty was estimated for five separation distances with an extended two-tower approach which removed systematic differences of CO2 fluxes measured at two EC towers. This analysis was made for a dataset where (i) only similar weather conditions at the two sites were included and (ii) an unfiltered one. The extended approach, applied to weather-filtered data for separation distances of 95 m and 173 m gave uncertainty estimates in best correspondence with the independent reference method The introduced correction for systematic flux differences considerably reduced the overestimation of the two-tower based uncertainty of net CO2 flux measurements, e.g. caused by different environmental conditions at both EC towers. It is concluded that the extension of the two-tower approach can help to receive more reliable uncertainty estimates because systematic differences of measured CO2 fluxes which are not part of random error are filtered out.

scholarly journals Effects of Different Water Management and Fertilizer Applications on CO2 Fluxes from a Selected Myanmar Rice (Oryza sativa L.) Cultivar

2020 ◽  
pp. 22-37
Author(s):  
Saw Min ◽  
Martin Rulik
Keyword(s):  
Water Management ◽  
Co2 Emission ◽  
Management Practices ◽  
Oryza Sativa L ◽  
Management Practice ◽  
Co2 Flux ◽  
Organic Manure ◽  
Inorganic Fertilizer ◽  
Co2 Uptake ◽  
Co2 Fluxes

The application of nitrogen fertilizer and the water management practices are important to optimize potential yields in rice cultivation. Moreover, they may affect the emissions patterns of methane (CH4) and carbon dioxide (CO2) emission. Compared to methane, knowledge about the combined effects of different fertilizer rates together with different water management practices on CO2 fluxes are scarce. Therefore, this study aims to assess CO2 fluxes of a selected rice cultivar in response to different fertilizer applications and water management practices. The treatments included two different applications of inorganic fertilizer (recommended rate and farmer’s practice), organic manure application and water management practices; continuous flooding (CF) and alternate wetting and drying (AWD). Mean total CO2 flux in CF was -30.82 g CO2 m-2 d-1 during daytime and 29.64 g CO2 m-2 d-1 during nighttime. Surprisingly, the average net CO2 fluxes were negative under both CF (-49 mg CO2 m-2h-1) and AWD practices (-127 mg CO2 m-2h-1), indicating a net CO2 uptake by the rice plants. Inorganic fertilizer applications led to considerably higher net CO2 emissions compared to the control under both CF and AWD. Conversely, CO2 emission fluxes in the treatment with organic manure showed negative net CO2 fluxes under both water management practices and while revealing the same fresh biomass as observed in other treatments (inorganic fertilizer and control). Taken together, modifications of current cultivation systems toward using organic manure, that emit less CO2, could effectively mitigate CO2 impacts regardless of the selected water management practice.

Abiotic drivers of CO2 fluxes in the transition from the winter-to-spring in coniferous forest and bog in central Siberia

2021 ◽  
Author(s):  
Sung-Bin Park
Keyword(s):  
Coniferous Forest ◽  
Net Ecosystem Exchange ◽  
Co2 Flux ◽  
Multivariate Adaptive Regression Splines ◽  
Co2 Uptake ◽  
Co2 Fluxes ◽  
Legacy Effect ◽  
Uptake Rates ◽  
Before And After ◽  
Soil Temperatures

&lt;p&gt;The transition winter-to-spring is essential for understanding the seasonal dynamics of CO2 flux in high northern latitudes. However, the latest CO2 flux measurements in the two dominant boreal ecosystems, i.e. coniferous forests and bogs are still insufficient. We investigated interannual variability of CO2 fluxes and their major drivers measured in a coniferous forest and a bog from 2013-2017 in Zotino, Russia. To better understand the controlling factors, we utilized the&amp;#160; Multivariate Adaptive Regression Splines (MARS) model. The two ecosystems showed clear differences in the timing of the start of CO2 uptake and CO2 flux rates before and after snowmelt. Both ecosystems started the net CO2 uptake even the snowmelt was incompleted. CO2 flux variations of coniferous forest were more sensitive to changes in air temperature than soil temperature than that of the bog. It is likely that intermittent frost events can reduce the magnitude of CO2 uptake rates of both ecosystems, however, CO2 uptake rates increased with a similar level as pre-frost within a few days. In 2015, both ecosystems reached the highest cumulative net ecosystem exchange of CO2 because of the unusually warm temperature in May compared to the study period.&amp;#160;Our findings reveal that continuous and long-term monitoring of the effects of air and soil temperatures on vegetation productivity as well as their legacy effect in subarctic ecosystems required further to be studied.&lt;/p&gt;

scholarly journals Mechanisms of the Sea–Air CO<sub>2</sub> Flux Seasonal Cycle biases in CMIP5 Earth Systems Models in the Southern Ocean

2017 ◽  
Author(s):  
N. Precious Mongwe ◽  
Marcello Vichi ◽  
Pedro M. S. Monteiro
Keyword(s):  
Southern Ocean ◽  
Seasonal Cycle ◽  
Dissolved Inorganic Carbon ◽  
Co2 Flux ◽  
Cmip5 Models ◽  
Co2 Uptake ◽  
Co2 Solubility ◽  
Group A ◽  
Group B

Abstract. The Southern Ocean forms a key component of the global carbon cycle. Recent studies, however, show that CMIP5 Earth System Models (ESM) disagree on the representation of the seasonal cycle of the CO2 flux (FCO2) and compare poorly to observations in the Southern Ocean. This model-observations bias has important implications on the ability of ESMs to predict century scale CO2 sink and related climate feedbacks. In this study, we used a specialized diagnostic analysis on 10 CMIP5 models in the Southern Ocean to discriminate the role of the major drivers, namely the temperature control and the concentration of dissolved inorganic carbon (DIC). Our analysis shows that the FCO2 biases in CMIP5 models cluster in two major groups. Group A models (MPI-ESM-MR, NorESM2 and HadGEM-ES) are characterized by exaggerated primary production such that biologically driven DIC changes mainly regulate the seasonal cycle of FCO2. Group-B (CMCC-CESM, GFDL-ESM2M, IPSL-CM5A-MR, MRI-ESM, CanESM2, CNRS-CERFACS) overestimates the role of temperature and thus the change in CO2 solubility becomes a dominant driver of FCO2 variability. While CMIP5 models mostly show a singular dominant influence of these two extremes, observations show a modest influence of both, with a dominance of DIC regulation. We found that CMIP5 models overestimate cooling and warming rates during autumn and spring with respect to observations. Because of this, the role of solubility is overestimated, particularly during these seasons (autumn and spring) in group B models, to the extent of contradicting the biological CO2 uptake during spring. Group A does not show this solubility driven bias due to the overestimation of DIC draw down. This finding strongly implies that the inability of the CMIP5 ESMs to resolve CO2 biological uptake during spring might be crucially related to the sensitivity of the pCO2 to temperature in addition to underestimated biological CO2 uptake.

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