Epsilon Archive for Student Projects

Abstract

The thesis is about forestry and its effects on the export of Dissolved Organic Carbon (DOC) to stream water. Forestry is of large importance for the Swedish society and important for our economy. But there are also some ecological drawbacks with the industry. This thesis is set out to test how we can manage forestry in a more sustainable way. A well known consequence of clear cutting is a groundwater table rise because of decreased evapotranspiration and a higher snow accumulation in the clear cut area when the trees are felled. With a higher groundwater table there will be an increased runoff of water to the streams, and superficial DOC rich soil layers will be connected to the soil water and export more DOC to the stream. With a higher DOC concentration the streams and lakes can turn into CO2 sources and the physical environments run the risk to be changed. An increased DOC transport can also affect the pH and the transport of metals and organic pollutants.
The sampling area is located in Balsjö 70 km west of Umeå. The area consists of two treated areas, one totally clear cut and one with a buffer zone along the stream. There are also two untreated control areas. To examine the effects of forestry the DOC concentration, estimated from absorbance measurements at 254 nm, is compared between the treated sites and the controls. Automatic water sampling devices (ISCOs) was used in all four sites to collect stream water samples that later was analyzed in the lab. The results show that there are higher concentrations of DOC from the treated sites than the controls. In other words an effect caused by the forestry. But there is also a difference between the controls in DOC export. This difference could derive from different riparian wetlands, which is established as an important DOC source