Changes in chemical and biological characteristics of soil after fire in Zagros forests

Fire is an ecological factor in the forest, during which most of the growing plants are damaged. By burning the vegetation on the soil surface, fire can cause negative or even positive effects on the physical, chemical, biological, and vegetation properties of the soil. Due to the fact that so far many studies have been done on the effect of natural fires on the characteristics of soil and vegetation, but researches on the impact of fire at different times of the growing season and the effect of those characteristics on soil and vegetation in Iran and other parts of the world are few. There are minimal resources in this field, so this research can provide appropriate information about the condition of the soil after the fire, as well as the ability to restore and restore valuable plant species and preserve the Zagros forests at the discretion of researchers. In this research, the effect of fire in the three seasons of spring, autumn, and winter on the chemical and biological characteristics of soil was investigated.

 The studied area was a part of Zagros forests in Kermanshah province. In this research, a control area was also considered in addition to the burned forests. For this purpose, the desired points (9 points for under the crown and 9 points for outside the crown in both control and burned areas) were determined by measuring with a meter on the transects (6 transects) and regularly and with time intervals. Specified (once every 2 months), they were sampled. The distance of the samples from each other in each row was 20 m and the distance between the rows was 50 m so that 3 rows were identified in the burned area and 3 rows in the control area. Soil properties were measured by conventional laboratory methods.

The results of the investigations show that the fire that occurred in the studied area (under the canopy and outside the canopy of trees in the Zagros region) was superficial and was capable of causing small changes in the chemical and biological factors of the soil. Only soil respiration rate and absorbable phosphorus were affected in this surface fire. The amount of phosphorus in the soil increased and then decreased to its initial level in the first month of sampling.

Considering that the fire in the study area was superficial and caused slight changes in soil characteristics in all sampling months. Probably, severe fires have the ability to cause extensive changes in the chemical, physical and biological characteristics of the soil, and the sampling time in different months did not have much effect on the results.