Temperaturens och den fotosyntetiskt aktiva strålningens effekt på avgång och inlagring av kol på en dikad torvjord

Sammanfattning: The decomposition of organic carbon in drained peat soils is a major source of carbon di-oxide in Sweden. A big part of these drained peat soils are used in agriculture and it is a big challenge to slow down their decomposition. It has earlier been thought that less tilling and higher water table levels would decrease the activity of soil microbes and thereby the decomposition, but recent experiments has showed that this has little or no effect. In this bachelor thesis a field experiment was made on drained peat soil with ley, outside Björklinge, Uppsala municipality, Sweden. The experiment was carried out in May 2011. The objective was to develop a method to examine how the net exchange of carbon diox-ide from plant covered peat soil is affected by temperature and photosynthetically active radiation (PAR). Soil respiration (RTOT) and net ecosystem exchange (NEE) was measured with manual and automatic soil respiration chambers. RTOT was measured with opaque chambers while NEE was measured with transparent chambers to allow photosynthesis to occur. From the acquired data values of carbon dioxide emissions the size of photosynthe-sis (PG) was calculated. At the second half of the experiment period, one of the automatic lysimeters was equipped with light dimming net hoods. This was made to make it possible to calculate the influence of PAR on NEE. There was an apparent correlation between soil temperature and RTOT and PAR and pho-tosynthesis.