Effects of experimental ground fires in various intensities on soil microbial biomass in old-growth black pine stands: A case study on the Osmancik Forest Planning Unit, Turkey

In this study, it was aimed to investigate the effects of the experimental fires on soil microbial biomass in the Osmancık Forest Management Unit in December 2013. For this purpose, soil samples were taken regularly from the burned areas where the intensity of the fire were medium and low and the surface was in flat and sloping on the old-growth black pine stands. In order to measure soil microbial biomass, 384 soil samples were taken at 0-5 cm and 5-10 cm depth stages from 96 randomly selected sampling points in December 2013, December 2014, April 2015 and October 2015. The Chloroform fumigation-extraction method was used for the soil analysis to determine microbial biomass. The results showed that in December 2013, the fire-reducing effect was observed on both microbial carbon and microbial nitrogen. In December 2014, microbial nitrogen and carbon averages were found to be low according to control zones. In general, the microbial carbon and nitrogen averages through the study site were reached to the same level as in the control sites in April 2015 and October 2015, but in some areas higher results were obtained. Especially in the period of October 2015, the increase of the carbon and nitrogen in the soil more than the increase of the microbial nitrogen in the control fields can be attributed to the increased microbial activity of the microorganisms towards the end of the vegetation period.