Changes Of Soil Chemical Properties And Its Influencing Factors In Pinus Sylvestris Var.mongolica Plantation In Liaoning Province

In this paper,field investigation and laboratory experiment were used to study the changes of soil carbon,nitrogen,phosphorus and ecological stoichiometry in 0-40 cm soil layer of Pinus sylvestris var.mongolica artificial mature forest growing in semi-arid and humid areas of Liaoning Province(adjacent original land use as control).The results showed that:(1)The change of soil organic carbon in humid areas was significantly higher than that in semi-arid areas.The total nitrogen content of soil increases in humid areas,but decreases in semi-arid areas.The change of total phosphorus in semi-arid area is obviously higher than that in humid area.The changes of C/P ratio and N/P ratio in wet area are obviously higher than those in arid area.(2)The change of surface soil organic carbon in semi-arid area is obviously higher than that in other soil layers,and decreases gradually with the increase of soil depth.The change of soil organic carbon in 30-40 cm deep layer in humid area is obviously higher than that in other soil layers.The change of nitrogen in the surface soil of the two climatic regions is higher than that of other soil layers.The relative change of soil total phosphorus in wet area and semi-arid area is obviously higher than that in other soil layers in the depth of 30-40 cm.(3)The change of soil organic carbon in the semi-arid area in 20-30 cm soil layer is mainly affected by soil available phosphorus,while the change of soil available phosphorus in 0-5cm soil is mainly affected by soil pH,and the change of soil available phosphorus in 5-10 cm soil is significantly affected by soil alkali-hydrolyzable nitrogen.The total nitrogen in 0-5cm and 20-30 cm soil layers in humid areas is mainly affected by soil moisture content,and the change of soil nitrogen-phosphorus ratio in 5-10 cm soil layer is mainly affected by the change of soil pH.Compared with semi-arid areas in Liaoning Province,the construction of Pinus sylvestris plantations in humid areas is more conducive to the accumulation of soil nitrogen.The accumulation of soil nitrogen in semi-arid areas is relatively slow,so the decomposition of forest litter in this area should be promoted to avoid the limitation of carbon and nitrogen deficiency in the growth and development of Pinus sylvestris var.mongolica,while the accumulation of soil phosphorus in humid areas is relatively small,so artificial auxiliary management measures should be taken to ensure the sustainable management of Pinus sylvestris var.mongolica plantations in different climatic regions.