Enzyme activity of soils after large-scale fires under varying habitat conditions using different methods of forest regeneration
The studies were conducted in plantations and thickets of Scots pine established in fresh coniferous (Bśw), fresh mixed coniferous (BMśw) and wet mixed coniferous (BMw) forest habitats on the burnt area after the 1992 fire in the territory of the Rudy Raciborskie (Raciborskie Forests) and Potrzebowice (Notecka Primeval Forest) Forest Districts.
The measurements of soil enzyme activity were made twice in Potrzebowice and three times in Rudy Raciborskie. Soil samples from a depth of 0-25 cm were collected for biochemical analyses and the activity of urease, asparaginase, acid phosphatase and dehydrogenases was determined. The organic carbon content and soil pH were established.
The restocked areas in the Rudy Raciborskie Forest District showed considerably lower activity of all examined enzymes regardless of the habitat type – urease ca 60%, asparaginase – 70%, acid phosphatase – 80% and dehydrogenases over 70% compared with the control.
In the territory of the Potrzebowice Forest District, soil enzyme activity in all restocked areas was lower in comparison with the control only in the case of dehydrogenases (by 40% in Bśw and 25% in BMśw). Acid phosphatase activity was lower in Bśw (by 44%). Soil asparaginase activity was 2-3 times higher in both Bśw and BMśw habitats, while urease activity in Bśw was similar to the control and markedly higher than in BMśw (by 39%). The rate of soil regeneration after the fire expressed in soil enzyme activity depended on the restocking method. The activity of the examined enzymes was found to be considerably higher in plantations established by planting and higher in BMśw compared with Bśw.
A decrease in enzyme activity of soils in the burnt areas persisting for nearly ten years after the fire indicates that the recovery of microbiocoenosis in the soils degraded by fire has not been completed. It also points to the usefulness of the studies on enzymatic activity as a sensitive indicator of soil response to stress factors.
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