En analys av nattliga koldioxidflöden i en boreal barrskog avseende spatial och temporal variation
Physical geographyGeomorphologyBoreal forestsSwedenGreenhouse effectCarbon dioxide fluxesPedologyCartographyClimatologyNaturgeografiGeomorfologiMarkläraKartografiKlimatologiEarth and Environmental Sciences
Carbon dioxide in the atmosphere contributes to the greenhouse effect, which is essential tolife on our planet. Furthermore, it plays an important part of the photosynthesis andrespiration of the world?s organisms. Since the start of the industrial revolution the amount ofcarbon dioxide in the atmosphere has increased exponentially. The main source is theextensive burning of fossil fuels. If the amount of carbon dioxide in the atmosphere growseven more it will increase the greenhouse effect and cause global climatic change.Fortunately, there is a ?missing sink? slowing down the atmospheric increase of carbondioxide. Most likely the ?missing sink? is related to the biosphere.The purpose of this work was to analyse nighttime carbon dioxide fluxes from a borealconiferous forest, and to map its spatial and temporal variations. The measurements used inthe analysis were collected in Norunda (just north of Uppsala, Sweden) between 1994 and1998 as part of the NOPEX-project.The analysis showed an exponential correlation between the carbon flux and the airtemperature (r2=0.43, Q10=2.94). No evident connection between the carbon flux and theatmospheric stability was found. During single summer nights there were frequently strongvariations in the measured carbon fluxes that could not be explained by variations intemperature. These variations occurred also when atmospheric mixing was adequate withfriction velocities above 0.4 m/s. There appeared four distinctly different wind directionsectors that showed significantly different respiration levels. These sectors were weaklycorrelated to differences in stand properties. A PLS-model for the carbon flux was createdwith several predictors. The model gave only slightly better results (r2=0.47) compared withestimates from temperature alone.For an eventual follow-up data should be complemented with soil temperatures plus fieldexams of the four observed wind sectors. The footprints of the carbon fluxes should also bemapped.