| Timberline is an important ecotone which controlled by climate. Human activities has small impact on the timberline, which is a sharp ecotone that the community structure changes drastically. Timberline is regarded as the potential indicator of climate change. Therefore timberline has become one of the hots pots in globle climate change research.The research on timberline has become one of the major concerns in the aspect of global climate change. Timberline shift was tree change in this area. The species composition of trees and vegetation type will affect the composition of litter and roots, which will cause the change of SOC, MBC, NPK content. In addition, oil indicators of these nutrients also affect the plant growth and the change of forest community, which will promote timberline dynamics. Study the SOC, MBC, NPK content in different condition of terrain and different environmental factors. Therefore the research terrain factors of soil organic carbon, microbial biomass carbon and NPK influence is very important.The soil of timberline in Qinling Mountains was selected to study the distribution of SOC, MBC, TN, AK, AP content. This paper aimed to understand the relationship between terrain and SOC, MBC, NPK content, which enrich ecotones ecological theory of evolution, and ultimately to provide a theoretical basis in Qinling mountains. The results iare as follows:(1) In this study, the content of the forest SOC, MBC, TN, AP, AK in the district is generally high, and the AK content reached a high of potassium levels. In0-40cm vertical soil profile, the upper SOC, MBC, TN, AK, AP values were higher than lower.(2) Correlation analysis showed that the altitude has a significant effect on the microbial biomass carbon and available phosphorus, soil microbial biomass carbon in different altitude were very significant positive correlated. Soil available phosphorus content and altitude had extremely significant negative correlation, soil phosphorus decreases with increasing altitude. K content and altitude correlation is not significant. This suggests that elevation is one of the important factors of soil microbial biomass carbon and available phosphorus content(3) slope and the lower soil microbial biomass carbon and available phosphorus content showed a significant positive correlation,and soil organic carbon and total nitrogen in different slope was significantly lower negative correlation. In the study area, when the slope>35°, the soil organic carbon and nutrient content is higher than other low-slope, indicating a certain slope has a beneficial impact on the accumulation of soil organic carbon and nutrients.(4) The correlation of soil organic carbon and NPK content in different slope is not significant. However, the highest of soil organic carbon, total nitrogen, microbial biomass carbon, potassium, available phosphorus content in shady, and shady distribution overall:presentation> sunny law, because of the high soil biomass in shady, returned to the soil litter and humus rate more quick than the root object of soil organic carbon and nutrient release rate, which is roughly the same with relevant scholars.(5) The altitude, slope and exposure can response to local environmental quality, the effects of altitude, exposure, slope by the local distribution of forest vegetation types and different, thereby affecting the forest soil properties; in turn, soil properties with the heat, moisture and other ecological factors affect vegetation system, thereby affecting their litter and humus kind of process. In the three influencing factors, the correlation between the maximum altitude, followed for the slope, the minimum is exposure, but the law of each index variation with altitude change is inconsistent. |
