Response Of Soil Enzyme Activity And Chemical Properties To Nitrogen Addition In The Korean Pine Plantation

Biogeochemical cycle is one of the important domain of ecological study,while carbon and nitrogen cycle,as hard core,are being the hot research topic.Nitrogen is the essential macro-element to constitute biology,and it is also the important nutrient source for biology living.Terrestrial ecosystem,especially temperate forest,most of them are nitrogen restricted.Since the industrial revolution,the activities as burning mineral fuel and using nitrogenous chemical fertilizer have resulted in atmosphere nitrogen deposition rapid increase.The sustained increase of nitrogen deposition can change nitrogen status of forest ecosystem,and then temperate forest gradually transform into nitrogen saturation status from nitrogen restricted status.The each transformed way of nitrogen and carbon in soil has a certain amount of change affected by nitrogen deposition.Soil enzymes participate in many complex biochemical processes in soil and play an important role in the material circulation of terrestrial ecosystems.In order to explore the response of soil enzyme activity and chemical properties to nitrogen deposition in temperate forest,this study analyzes four soil enzyme activity and chemical properties in different treatment ways based on Pinus koraiensis artificial forest nitrogen addition experiment sample plot in Hei Longjiang liangshui national natural reserve.The results proved that the activities of NAG and AKP in soil increased significantly with the increasing of nitrogen concentration,while the activities of BG and ACP had no significant difference in various nitrogen processes.Only carbon content increased significantly with the increasing of nitrogen concentration in soil chemical property,other chemical property had no significant difference in various nitrogen processes.The contents of total carbon,total nitrogen,total phosphorus,effective nitrogen and the activity of four enzymes in the upper layer(0?10 cm)of the same nitrogen application level were significantly higher than those in the lower layer(10?20 cm),while the pH value,carbon nitrogen ratio,carbon phosphorus ratio and nitrogen phosphorus ratio had no significant variation among different soil layers.Total carbon had very significant positive correlation with NAG,BG,AKP,ACP.Total nitrogen had significant or extremely significant positive correlation with BG,NAG,AKP,ACP.Effective nitrogen had significant or extremely significant positive correlation with NAG,AKP.Total phosphorus had significant or extremely significant positive correlation with ACP,AKP.Carbon and nitrogen ratio had extremely significant positive correlation with ACP.Carbon and phosphorus ratio had significant positive correlation with NAG,BG,ACP.Different types of enzyme activities had different responses to nitrogen addition,the rise of NAG and AKP enzyme activities may increase the risk of leaching of nutrient elements in soil.The stoichiometric ratio of the medium nitrogen group had significantly higher than that of the low nitrogen group,while other groups have no significant difference.Four types hydrolase have linear correlation relationship with carbon content,have correlation relationship with other part nutrient content,which illustrate that carbon content has close relationship with enzymatic activity.Nitrogen application level and soil layer have different effects on soil enzyme activity and soil chemical properties.Long-term and large input of nitrogen can directly or indirectly change soil chemical properties and influence soil enzyme activity.