The purpose of the study was to examine how forest harvesting affects the accumulation of carbon dioxide (CO2) and methane (CH4) under the ice-cover. Dissolved organic carbon (DOC) was hypothesized to increases post-harvest, this supplementation would in turn lead to an increased accumulation of CO2 and CH4 under the ice-cover. Four small boreal lakes, (two treatment lakes, two reference lakes) were sampled once a year during winter, under a three-year period (2012-2014). The sampling was performed using a headspace equilibration technique. During the three study years (2012-2014), the CO2 concentration increased in both the reference lakes and the harvested lakes (percentage increase; 18 % and 89 % respectively). The mean CH4-concentration in the reference lakes increased during the years 2012-2014, (2, 6, 7.5 μM). While the concentrations in the harvested lakes showed a slightly different pattern, with a peak during year 2013 which latter decreased until year 2014, (6, 12.5, 8.5 μM). The result of this study suggests that harvest in the catchment area increases the accumulation of CO2 and possible CH4 under the ice. Inflow of supersaturated surface water was found to be a more important source to the increased accumulation under ice than DOC, contradicting the previous hypothesis that DOC would be a more important factor controlling the CO2 and CH4 production. Moreover this study indicates that the dimension of the edge-zone left in connection to the inlets can be of crucial importance, possible reducing the amount of supersaturated surface water reaching the lakes.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:umu-90636 |
| Date | January 2014 |
| Creators | Landström, Emelie |
| 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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