Nitrogen Content Changes in Fire-Affected Forest Soils Under Different Tree Species in Region of Southeast Bulgaria

Emiliya Velizarova, Ibrahim Molla

Abstract: In the present study, the content of nitrogen in Chromic Luvisols from the Eastern Rhodopes and the southern slopes of Sakar Mountain, under various tree species affected by forest fires, was investigated. Soil samples for analysis were taken from 0 to 5 cm and from 5 to 20 cm of soil layers of affected and non-fire-affected soils, immediately after the fire impact and in dynamics of up to one year. Samples were also taken from the litter with a 25 cm x 25 cm pattern area.
The changes in the nitrogen content were determined and the ratio of C: N was estimated. The changes in the nitrogen content of the studied soils under different tree species were found to be rather variable. The results show that forest fires cause greater changes in nitrogen content in the surface 5 cm soil layer. An increase in the mean nitrogen content of the soil under the Austrian Pine plantation with Δ N = 0.044% (± 0.013) was found, whereas in the soil from the oak stand and Scots pine plantation, the nitrogen content decreased with mean nitrogen content changes Δ N = -0.076% (± 0.012) and Δ N = -0.025% (± 0.008) respectively. The fires led to nitrogen content decrease in the forest litter from all studied tree species areas, but the most significant is that from oak stand by 0.184% (± 0.024) relative to the control. The changes occurring in the nitrogen content of the soil and the forest bed also lead to changes in the ratio C:N immediately after a fire, and in dynamics the changes are maintained for up to three months.

Keywords: C:N; forest fire; Luvisols; nitrogen; tree species

Date published: 2017-07-26