The study compared soil nitrogen levels in different types of forests and shrub-land in a semi-arid area. They looked at various factors like organic carbon, nitrogen content, and enzyme activity in the soil. The results showed that soil nitrogen levels varied between the different types of vegetation. Pine forests had higher inorganic nitrogen, while shrub-land had higher organic carbon and total nitrogen. As soil depth increased, some factors like nitrogen content decreased while others like denitrification enzyme activity increased. Overall, the type of vegetation had a significant impact on the nitrogen cycle in the soil.