摘要
This study was conducted in Juniperus excels a stands on the southern slopes of Iran’s Alborz Mountains,to determine the effects of fire and seasonal variations on soil physicochemical properties and enzyme activities.A total of 64 composite soil s amples were randomly collected in the spring and fall from two burned and unburned sites at depths of 0-10 and 10-20 cm.The results of a two-way ANOVA analysis indicate that fire increased the organic carbon(OC),total nitrogen(TN),and available phosphorus(P_(ava)) contents of the soil by 16%,59%,and 53%,respectively.Similarly,when burned sites were compared to unburned sites,the activities of acid phosphatase(ACP) and urease enzymes increased by 73% and 12%,respectively.Nevertheless,fire did not affect soil texture,bulk density(BD),pH,electric conductivity(EC),exchangeable potassium(Kexc),or the activities of alkaline phosphatase(ALP) and dehydrogenase.According to two-way ANOVA results,OC,TN,P_(ava),K_(exc),and EC values were significantly higher in the fall,whereas pH and ALP values were significantly higher in the spring.Additionally,phosphorous and dehydrogenase activity were significantly different in selected soil factors at 0-10 and10-20 cm depths.The interaction of fire,season,and soil depth were significant for phosphorous and urease.Moreover,the activity of ALP correlated well with pH(r=0.68),P(r=-0.74),OC(r=-0.53),and TN(r=-0.37),whereas the activity of ACP correlated significantly with OC(r=0.64) and TN(r=0.71).Two years after the fire,soil properties in J.excels a stands had either improved or remained unaffected,returning to pre-fire levels.Additionally,soil chemical properties varied significantly across sampling seasons,which should be considered when comparing and interpreting soil data in future research.
