SHORT-TERM EFFECTS OF PRESCRIBED FOREST FIRE ON SOIL MITES (ACARI)

Natural forest fires are considered as a part of natural ecosystem processes. Short-term effects of prescribed fire on densities and taxonomic diversity of soil Acari were studied in fresh pine mixed forest ("Biala" forest) in the Mazovia region, Central-Eastern Poland. Three plots (size 1 m(2)) of similar soil type and vegetation were selected for prescribed burning. Soil samples of an area of 10 cm(2) and the depth of 5 cm were collected in June 2005 - one day after the burning, 60 days after the burning and 90 days after the burning. Samples were collected from within the border of the burned plots, from the border itself, as well as from the surroundings. Due to the burning, the density of Acari communities decreased from 11.5 x 10(3) ind. m(-2) recorded in the surroundings to 3.2 x 10(3) ind. m(-2) recorded in the burned plots. Values recorded within the burned plots after the fire differed significantly from those recorded on the border (P = 0.05) and in the surroundings (P = 0.0001). After 60 days, an increase in Acari abundance was observed in the burned plots (P = 0.02), becoming similar to that noted for the border of the plot and for the surroundings. After 90 days, there were no significant differences between the burned parts of the plots, their borders and the surroundings; however, generally decreased densities were observed, possibly due to the seasonal reason. The observed changes suggest the restoration of Acari community after disturbance.