Large amounts of carbon (C) are stored in tundra soils. Global warming may turn tundra ecosystems from C sinks into sources or vice versa, depending on the balance between gross primary production (GPP), ecosystem respiration (ER) and the resulting net ecosystem exchange (NEE). We aimed to quantify the summer season C balance of a 27 km2 tundra landscape in subarctic Sweden. We measured CO2 fluxes in 37 widely distributed plots across five tundra vegetation types and in 7 additional bare soil plots, to assess effects of abiotic and biotic components on C exchange. C fluxes in bare soils were low and differed to all vegetation types. Thus, accounting for differences between bare soils and vegetated parts is crucial for upscaling a C balance using a landcover classification map. In addition, we found that both NEE and ER, varied within and across different tundra vegetation types. The C balance model for the growing season 2016 revealed a net C loss to the atmosphere. Most vegetation types acted as CO2 sources, with highest source strength in dense shrub vegetation at low elevations. The only considerable C sinks were graminoid-dominated upland meadows. In addition, we found a shift in C balance between different heath vegetation types, ranging from C source in dense deciduous shrub vegetation (Mesic Heath and Dry Heath) to C sink in low growing shrub vegetation (Extremely Dry Heath). These results highlight the importance to account for differences between vegetation types when modelling C fluxes from plot to landscape level.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:umu-132765 |
| Date | January 2017 |
| Creators | Borgelt, Jan |
| Publisher | Umeå universitet, Institutionen för ekologi, miljö och geovetenskap |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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