Carbon fluxes and nitrogen availability along an urban–rural gradient in a desert landscape

2009 ◽  
Vol 13 (1) ◽  
pp. 1-21 ◽  
Author(s):  
Brenda A. Koerner ◽  
Jeffrey M. Klopatek
Keyword(s):  
Nitrogen Availability ◽  
Carbon Fluxes ◽  
Urban Rural ◽  
Desert Landscape

scholarly journals A model for urban biogenic CO<sub>2</sub> fluxes: Solar-Induced Fluorescence for Modeling Urban biogenic Fluxes (SMUrF v1)

2021 ◽  
Vol 14 (6) ◽  
pp. 3633-3661
Author(s):  
Dien Wu ◽  
John C. Lin ◽  
Henrique F. Duarte ◽  
Vineet Yadav ◽  
Nicholas C. Parazoo ◽  
...  
Keyword(s):  
Urban Areas ◽  
Fossil Fuel ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Growing Season ◽  
Carbon Fluxes ◽  
Co2 Fluxes ◽  
Biogenic Carbon ◽  
Urban Rural ◽  
Biogenic Fluxes

Abstract. When estimating fossil fuel carbon dioxide (FFCO2) emissions from observed CO2 concentrations, the accuracy can be hampered by biogenic carbon exchanges during the growing season, even for urban areas where strong fossil fuel emissions are found. While biogenic carbon fluxes have been studied extensively across natural vegetation types, biogenic carbon fluxes within an urban area have been challenging to quantify due to limited observations and differences between urban and rural regions. Here we developed a simple model representation, i.e., Solar-Induced Fluorescence (SIF) for Modeling Urban biogenic Fluxes (“SMUrF”), that estimates the gross primary production (GPP) and ecosystem respiration (Reco) over cities around the globe. Specifically, we leveraged space-based SIF, machine learning, eddy-covariance (EC) flux data, and ancillary remote-sensing-based products, and we developed algorithms to gap-fill fluxes for urban areas. Grid-level hourly mean net ecosystem exchange (NEE) fluxes are extracted from SMUrF and evaluated against (1) non-gap-filled measurements at 67 EC sites from FLUXNET during 2010–2014 (r>0.7 for most data-rich biomes), (2) independent observations at two urban vegetation and two crop EC sites over Indianapolis from August 2017 to December 2018 (r=0.75), and (3) an urban biospheric model based on fine-grained land cover classification in Los Angeles (r=0.83). Moreover, we compared SMUrF-based NEE with inventory-based FFCO2 emissions over 40 cities and addressed the urban–rural contrast in both the magnitude and timing of CO2 fluxes. To illustrate the application of SMUrF, we used it to interpret a few summertime satellite tracks over four cities and compared the urban–rural gradient in column CO2 (XCO2) anomalies due to NEE against XCO2 enhancements due to FFCO2 emissions. With rapid advances in space-based measurements and increased sampling of SIF and CO2 measurements over urban areas, SMUrF can be useful to inform the biogenic CO2 fluxes over highly vegetated regions during the growing season.

scholarly journals Effects of nitrogen fertilization on the understorey carbon balance over the growing season in a boreal Pine forest

2013 ◽  
Vol 10 (8) ◽  
pp. 14093-14113
Author(s):  
D. B. Metcalfe ◽  
B. Eisele ◽  
N. J. Hasselquist
Keyword(s):  
Boreal Forests ◽  
Nitrogen Availability ◽  
Growing Season ◽  
Carbon Fluxes ◽  
Nitrogen Addition ◽  
Carbon Uptake ◽  
Sink Strength ◽  
Understorey Vegetation ◽  
Ecosystem Carbon ◽  
Photosynthetic Carbon

Abstract. Boreal forests play a key role in the global carbon cycle and are facing rapid shifts in nitrogen availability with poorly understood consequences for ecosystem function and global climate. We quantified the effects of nitrogen availability on carbon fluxes from a relatively understudied component of these forests – understorey vegetation – at three intervals over the summer growing period in a northern Swedish Scots Pine stand. Nitrogen addition altered both photosynthetic carbon uptake and respiratory release, but the magnitude and direction of this effect depended on the time during the growing season and the amount of nitrogen added. Specifically, nitrogen addition stimulated net ecosystem carbon uptake only in the late growing season. We find evidence for species-specific control of understorey carbon sink strength, as photosynthesis per unit ground area was positively correlated only with the abundance of the vascular plant Vaccinium myrtillus and no others. Comparison of photosynthetic carbon uptake with data on plant carbon dioxide release from the study site, indicate that understorey vegetation photosynthate was mainly supplying respiratory demands for much of the year. Only in the late season with nitrogen addition did understorey vegetation appear to experience a large surplus of carbon in excess of respiratory requirements. Further work, simultaneously comparing all major biomass and respiratory carbon fluxes in understorey and tree vegetation, is required to resolve the likely impacts of environmental changes on whole-ecosystem carbon sequestration in boreal forests.

scholarly journals Effects of nitrogen fertilization on the forest floor carbon balance over the growing season in a boreal pine forest

2013 ◽  
Vol 10 (12) ◽  
pp. 8223-8231 ◽  
Author(s):  
D. B. Metcalfe ◽  
B. Eisele ◽  
N. J. Hasselquist
Keyword(s):  
Boreal Forests ◽  
Forest Floor ◽  
Nitrogen Availability ◽  
Environmental Changes ◽  
Vascular Plant ◽  
Growing Season ◽  
Carbon Fluxes ◽  
Nitrogen Addition ◽  
Sink Strength ◽  
Understorey Vegetation

Abstract. Boreal forests play a key role in the global carbon cycle and are facing rapid shifts in nitrogen availability with poorly understood consequences for ecosystem function and global climate change. We quantified the effects of increasing nitrogen availability on carbon fluxes from a relatively understudied component of these forests – the forest floor – at three intervals over the summer growing period in a northern Swedish Scots pine stand. Nitrogen addition altered both the uptake and release of carbon dioxide from the forest floor, but the magnitude and direction of this effect depended on the time during the growing season and the amount of nitrogen added. Specifically, nitrogen addition stimulated net forest floor carbon uptake only in the late growing season. We find evidence for species-specific control of forest floor carbon sink strength, as photosynthesis per unit ground area was positively correlated only with the abundance of the vascular plant Vaccinium myrtillus and no others. Comparison of understorey vegetation photosynthesis and respiration from the study site indicates that understorey vegetation photosynthate was mainly supplying respiratory demands for much of the year. Only in the late season with nitrogen addition did understorey vegetation appear to experience a large surplus of carbon in excess of respiratory requirements. Further work, simultaneously comparing all major biomass and respiratory carbon fluxes in forest floor and tree vegetation, is required to resolve the likely impacts of environmental changes on whole-ecosystem carbon sequestration in boreal forests.

scholarly journals A Model for Urban Biogenic CO<sub>2</sub> Fluxes: Solar-Induced Fluorescence for Modeling Urban biogenic Fluxes (SMUrF v1)

2020 ◽  
Author(s):  
Dien Wu ◽  
John C. Lin ◽  
Henrique F. Duarte ◽  
Vineet Yadav ◽  
Nicholas C. Parazoo ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Urban Areas ◽  
Fossil Fuel ◽  
Ecosystem Respiration ◽  
Growing Season ◽  
Carbon Fluxes ◽  
Co2 Fluxes ◽  
Biogenic Carbon ◽  
Urban Rural ◽  
Biogenic Fluxes

Abstract. When estimating fossil fuel carbon dioxide (FFCO2) emissions from observed CO2 concentrations, the accuracy can be hampered by biogenic carbon exchanges during the growing season even for urban areas where strong fossil fuel emissions are found. While biogenic carbon fluxes have been studied extensively across natural vegetation types, biogenic carbon fluxes within an urban area have been challenging to quantify due to limited observations and differences between urban versus rural regions. Here we developed a simple model representation, i.e., Solar-Induced Fluorescence (SIF) for Modeling Urban biogenic Fluxes ("SMUrF"), that estimates the gross primary production (GPP) and ecosystem respiration (Reco) over cities around the globe. Specifically, we leveraged space-based SIF, machine learning, eddy-covariance flux data, and additional remote sensing-based products, and developed algorithms to gap fill fluxes for urban areas. Grid-level hourly mean net ecosystem exchange (NEE) are extracted from SMUrF and evaluated against 1) non-gapfilled measurements at 67 eddy-covariance (EC) sites from FLUXNET during 2010–2014 (r > 0.7 for most data-rich biomes), 2) independent observations at two urban vegetation and two crop EC sites over Indianapolis from Aug 2017 to Dec 2018 (r = 0.75), and 3) an urban biospheric model based on fine-grained land cover classification within Los Angeles (r = 0.83). Moreover, we compared SMUrF-based NEE with inventory-based FFCO2 emissions over 40 cities and addressed the urban-rural contrast regarding both the magnitude and timing of CO2 fluxes. By examining a few summertime satellite tracks over four cities, we found that the urban-rural gradient in column CO2 (XCO2) anomalies due to NEE can sometimes reach ~ 0.5 ppm and be close to XCO2 enhancements due to FFCO2 emissions. With rapid advances in space-based measurements and increased sampling of SIF and CO2 measurements over urban areas, SMUrF can be useful for informing the biogenic CO2 fluxes over highly vegetated regions during the growing season.

Socio-Economic Characteristics of Immigrants in Western Greece Region: Urban – Rural Continuum or Divide?

2006 ◽  
Vol 3 (2) ◽  
pp. 91-105 ◽  
Author(s):  
Theodoros Iosifides ◽  
Thanasis Kizos ◽  
Elektra Petracou ◽  
Ekaterini Malliotaki ◽  
Konstantina Katsimantou ◽  
...  
Keyword(s):  
Rural Areas ◽  
Urban Centers ◽  
Spatial Factors ◽  
Limited Role ◽  
Urban Rural ◽  
Of Greece ◽  
Western Greece

This paper aims at an investigation of factors of differentiation of basic social and economic characteristics of foreign immigrants in the Region of Western Greece. The paper explores whether the thesis of urban-rural divide is relevant for the differentiation of immigrants’ socio-economic characteristics in a typical Region of Greece, where there is a strong interplay between major urban centers and large rural areas. Findings show that spatial factors play a very limited role in the differentiation of socio-economic characteristics of immigrants and indicate that other factors are more important. Thus, and as regards socio-economic characteristics of immigrants, the overall picture is that of urban-rural continuum rather than divide. 

Scaling the Necropolitical Anthropocene

2020 ◽  
Vol 9 (4) ◽  
pp. 77-91
Author(s):  
Tyler S. Rife
Keyword(s):  
Climate Change ◽  
Theoretical Concepts ◽  
Ecological Concept ◽  
Space And Time ◽  
Desert Landscape ◽  
Ecological Potential

In this essay, I demonstrate how the ecological concept of “scaling” carries potential to animate critical logics in the Anthropocene. I argue that scaling can expose unexpected linkages across space and time that help to denaturalize particular ecological formations as entangled, rather than separate. I demonstrate the critical ecological potential of scaling by performing it rhizomatically, weaving across scales of space and time while juxtaposing theoretical concepts with my experiences of life as a resident in the urban desert landscape of Phoenix, AZ. This ecology ultimately reveals how climate change acts as a complex necropolitic of the Anthropocene.

A review on the prerequisites of Evidence-Based Curriculum as a driver to skills development of the leather value chain in Africa

2019 ◽  
Vol 5 (1) ◽  
pp. 1-10
Author(s):  
Mwinyikione Mwinyihija
Keyword(s):  
Higher Education ◽  
Curriculum Design ◽  
Value Chain ◽  
Theoretical Perspective ◽  
Economic Benefits ◽  
Skills Development ◽  
Evidence Based ◽  
Wealth Creation ◽  
Urban Rural ◽  
Review Study

The review study closely introspects’ on the prerequisites of evidence-based curriculum within the realms of specialized skills development agenda as pursued through higher education Institutions in Africa. Explicitly, the constraining factors that bedevil the leather sector are identifiable when appropriate research designs tools are applied. As such, in the process of identifying the constraints, renascence themes could, therefore, be beneficial in collecting evidence in support of developing curriculum. Such a developed curriculum stands higher chances of acceptability and aptly mitigates against challenges related to specialized skills development. The review succinctly indicates that in the process of identifying the themes, the scope of collecting evidence becomes attainable, thus, improving curricula that entails a participatory and transformative orientation. Indeed, during the review phase of the study, three main perspectives are depicted to be consequential in attaining a comprehensive, evidence-based curriculum, such as; action research, backward curriculum design perspective and theoretical perspective. Therefore, about this perspective, a reflection based on personal experiences and related to new knowledge with what they already know leads to constructivism. The relevancy of a constructivist strategy is observed to facilitate the observatory and evaluative stance during the development of evidence-based curriculum. Moreover, in consolidating and sustaining the benefit of such a developed curriculum, threshold concept was found during the review that it complements the process and strengthens the collecting evidence for curriculum development. Accordingly, therefore, the result of the review study indicate that Africa would  position itself for initiating transformational changes in aspects of specialized higher education, fruition towards socio-economic benefits (e.g. employment, wealth creation and technology transfer), reversal of urban-rural or inter/intra continental migration flurry.

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