Dynamic Changes Of Soil Respiration Rate Of Artificial Forest Land Of Sugar Maple And Its Response To Nitrogen Disposition.

The dynamic change of soil respiration has close ties to the global climate warming and the carbon cycle in the terrestrial ecosystem,while increasing of atmospheric nitrogen deposition poses a growing threat to the regional ecological environment and global carbon cycle.Anhui province is one of the main areas of nitrogen deposition in China.Studied on dynamic changes in the soil respiration of Acer saccharum artificial forest land under the control(CK,0 g·m^-2·a^-1),low nitrogen(N₅,5 g·m^-2·a^-1)and high nitrogen(N₁₀,10g·m^-2·a^-1)three simulated nitrogen deposition process,which could be further clear the role of nitrogen in the soil,but also had some practical significance for the research of regional forest ecosystem on carbon cycle.The main results were as follows:?1?The daily changes of soil respiration rate of the A.saccharum artificial forest land in different month displayed single peak style,and the highest daily soil respiration rate appeared at 12:00-16:00.The monthly dynamic changes were linearly decreasing with the determination of the month.The maximum respiration rate occurred in July,the smallest in November.The order of the soil average respiration rate was July>August>June>October>September>November.?2?The effects of nitrogen deposition on soil respiration rate were different in different months.In June,the soil respiration rate under N₅ treatment was significantly higher than that of CK and N10?p<0.01?,the order of which was N5>CK>N10.From July to September,the order of the soil respiration rate was N₁₀>N₅>CK.In October and November,the order of the soil respiration rate was ranked by N5>N10>CK.?3?In contrast to CK,soil respiration rate of N₅ and N₁₀ were increased with the increase of nitrogen deposition contentions(except for N₁₀ in June).During June to August,the growth rate of soil respiration rate under N₅ treatment was 10-20%,and increased quickly in September,and was up to 13 times that in June occurred in November.At the same time,the highest growth rate of soil respiration rate under N₁₀ treatment was in July that of 58.4%,October was followed that of 55.8%,and the growth rate in August,September,and November were close,and their value were 33.7%-37.7%.?4?The relationship between soil respiration rate and soil temperature and soil moisture was in accord with the exponential model under different nitrogen concentration,and the highest correlation degree was N10 treatment,the lower was N5 treatment.The Q10was significantly different under different nitrogen concentration,and the Q₁₀ value under N₅ treatment was less than CK,which indicated that the concentration of N₅(5 g·m^-2·a^-1)decreased the sensitivity of soil respiration rate to temperature.The Q₁₀ value under N10treatment was greater than CK,indicating that the N₁₀ concentration(10 g·m^-2·a^-1)increased the sensitivity of soil respiration rate to temperature.?5?There was a significant correlation between soil respiration rates of forest land and the nitrogen concentration?p<0.01?.The nitrogen addition had different affects on the soil respiration rate.Under the CK treatment which was no nitrogen addition,the variation of soil respiration rate of 85.4%was due to the influence of soil physical and chemical properties and microbial activity.Under the N₅ treatment,the variation of soil respiration rate of 38.03%was due to nitrogen addition of 5 g·m^-2·a^-1.Under the N₁₀0 treatment,the variation of soil respiration rate of 51.72%was due to nitrogen addition of 10 g·m^-2·a^-1.