Diploma thesis (Spanien – Österreich): Title of the Project: “Effect of burning of Mediterranean macchia on ecosystem nitrogen stocks and the soil-atmosphere exchange of environmentally important gases (N 2 O, CH 4, NO/NO 2, N 2 ). For further information please contact: or at the Federal Research and Training Centre for Forests, Natural Hazards and Landscape Research and Training Centre for Forests, Natural Hazards and Landscapehttp://bfw.ac.at Microbial biomass: To see if microbial biomass C and N in humus layer and mineral soil changes after burning and over time. For determination microbial biomass C and N the fumigation-extraction method will be used. Sampling will be done before burning, after burning, 2 weeks, 4 weeks and 6 month after burning. Microbial community composition: With the PLFA method (Phospholipid fatty acid method bacterial and fungal community structure can be analysed. With this method we can analyse the amount and the percentage of different communities of bacteria and fungi. The aim is to determine if burning affects microbial populations and if the community structure changes shortly after burning or over time. Sampling will be done before burning, after burning, 2 weeks, 4 weeks and 6 month after burning. Measurement of potential GHG emissions (laboratory incubation) after burning and after ½ year: In order to see if potential soil GHG emissions changes at burned sites, CO 2, NO, N 2 O, CH 4 emissions/uptake will be measured from the burned and the control plots by incubating intact soil cores under different soil temperature and soil moisture conditions. Resin bags: will be installed to account for leaching of NO3- (and NH4+) in burned and control plots. They will be changed monthly. Future scenarios of climate change for the Mediterranean region suggest that intensity and length of summer drought periods will further increase and that annual precipitation will further decrease. These changes in climate will largely affect ecosystem C/N storage and turnover and the biosphere-atmosphere exchange of environmentally important trace gases. Prolonged drought periods are also likely to increase the frequency and likeliness of fires. So far it is known, that during burning of Macchia significant losses of carbon and nitrogen to the atmosphere occur in form of CO 2 and NO x and that mineral nitrogen is increased in the uppermost soil layers. However, knowledge about post-fire effects on ecosystem C and N stocks/turnover and the biosphere-atmosphere exchange of environmentally important trace gases (N 2 O, CH 4, CO 2, NO/NO 2, N2) is very restricted and has not been studied intensively so far. We will investigate the effects of fires (burning) on soil emissions of greenhouse gases (N 2 O, CH 4 ) and environmentally (NO/NO 2 ; N 2 ) important atmospheric gases and microbial C and N turnover as well as on soil and vegetation C and N stocks and turnover. Measurements: Time schedule: The thesis includes field work in Spain from end of September 2009 until middle of October 2009 and laboratory work at the BFW, Vienna (4-6 months).