En analys av nattliga koldioxidflöden i en boreal barrskog avseende spatial och temporal variation
An analysis of nightly carbon dioxide fluxes in a boreal coniferous forest considering spatial and temporal variation
Author
Summary, in English
Carbon dioxide in the atmosphere contributes to the greenhouse effect, which is essential to
life on our planet. Furthermore, it plays an important part of the photosynthesis and
respiration of the world’s organisms. Since the start of the industrial revolution the amount of
carbon dioxide in the atmosphere has increased exponentially. The main source is the
extensive burning of fossil fuels. If the amount of carbon dioxide in the atmosphere grows
even more it will increase the greenhouse effect and cause global climatic change.
Fortunately, there is a “missing sink” slowing down the atmospheric increase of carbon
dioxide. Most likely the “missing sink” is related to the biosphere.
The purpose of this work was to analyse nighttime carbon dioxide fluxes from a boreal
coniferous forest, and to map its spatial and temporal variations. The measurements used in
the analysis were collected in Norunda (just north of Uppsala, Sweden) between 1994 and
1998 as part of the NOPEX-project.
The analysis showed an exponential correlation between the carbon flux and the air
temperature (r2=0.43, Q10=2.94). No evident connection between the carbon flux and the
atmospheric stability was found. During single summer nights there were frequently strong
variations in the measured carbon fluxes that could not be explained by variations in
temperature. These variations occurred also when atmospheric mixing was adequate with
friction velocities above 0.4 m/s. There appeared four distinctly different wind direction
sectors that showed significantly different respiration levels. These sectors were weakly
correlated to differences in stand properties. A PLS-model for the carbon flux was created
with several predictors. The model gave only slightly better results (r2=0.47) compared with
estimates from temperature alone.
For an eventual follow-up data should be complemented with soil temperatures plus field
exams of the four observed wind sectors. The footprints of the carbon fluxes should also be
mapped.
life on our planet. Furthermore, it plays an important part of the photosynthesis and
respiration of the world’s organisms. Since the start of the industrial revolution the amount of
carbon dioxide in the atmosphere has increased exponentially. The main source is the
extensive burning of fossil fuels. If the amount of carbon dioxide in the atmosphere grows
even more it will increase the greenhouse effect and cause global climatic change.
Fortunately, there is a “missing sink” slowing down the atmospheric increase of carbon
dioxide. Most likely the “missing sink” is related to the biosphere.
The purpose of this work was to analyse nighttime carbon dioxide fluxes from a boreal
coniferous forest, and to map its spatial and temporal variations. The measurements used in
the analysis were collected in Norunda (just north of Uppsala, Sweden) between 1994 and
1998 as part of the NOPEX-project.
The analysis showed an exponential correlation between the carbon flux and the air
temperature (r2=0.43, Q10=2.94). No evident connection between the carbon flux and the
atmospheric stability was found. During single summer nights there were frequently strong
variations in the measured carbon fluxes that could not be explained by variations in
temperature. These variations occurred also when atmospheric mixing was adequate with
friction velocities above 0.4 m/s. There appeared four distinctly different wind direction
sectors that showed significantly different respiration levels. These sectors were weakly
correlated to differences in stand properties. A PLS-model for the carbon flux was created
with several predictors. The model gave only slightly better results (r2=0.47) compared with
estimates from temperature alone.
For an eventual follow-up data should be complemented with soil temperatures plus field
exams of the four observed wind sectors. The footprints of the carbon fluxes should also be
mapped.
Department/s
Publishing year
2000
Language
Swedish
Publication/Series
Lunds universitets Naturgeografiska institution - Seminarieuppsatser
Full text
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Document type
Student publication for Master's degree (one year)
Topic
- Earth and Environmental Sciences
Keywords
- geomorphology
- physical geography
- boreal forests
- Sweden
- greenhouse effect
- carbon dioxide fluxes
- pedology
- cartography
- climatology
- naturgeografi
- geomorfologi
- marklära
- kartografi
- klimatologi
Report number
75
Supervisor
- Anders Lindroth (Professor)