Effect of Simulated N Deposition on Soil Respiration in a Larix olgensis Plantation Forest

ZHANG Jiao;HAO Long-Fei;WANG Qing-Cheng;FU Jiao-Jiao;ZHU Kai-Yue;Northeast Forestry University;

Larix olgensis;;plantation forest;;N deposition;;soil respiration;;root respiration;;heterotrophic respiration

A two-year simulated N deposition experiment was conducted to explore the effects of different levels of nitrogen( N) deposition on soil respiration,with four different N supply levels,including control( CK,0g·m~(- 2)·a~(- 1)N),low( N1,5 g·m~(- 2)·a~(- 1)N),intermediate( N2,10 g·m~(- 2)·a~(- 1)N) and high level( N3,15 g·m~(- 2)·a~(- 1)N),in a 26-year-old Larix olgensis plantation forest in Mao'ershan experimental forest farm of northeast forestry university. Average annual soil respiration rate under different treatments was significantly promoted in the first year( P < 0. 05); Average annual soil respiration rate and heterotrophic respiration rate were significantly decreased under N2 and N3 treatments( P < 0. 05),respectively,and average annual soil respiration rate was significantly increased( P < 0. 05), heterotrophic respiration rate had no difference compared with control( P > 0. 05) under N1 treatment,in the second year. Soil microbial biomass carbon was significantly increased under N1 treatment( P < 0. 05),while N2 and N3 had no difference compared with control( P > 0. 05); Significantly positive exponential relationship was detected between soil respiration and soil temperature in 5 and 10 cm( P < 0. 01). The temperature sensitivity of soil respiration( Q_(10)) in both soil layer was increased under N1 treatment and decreased under N2 and N3 treatments compared with control,respectively. Soil respiration rate and its temperature sensitivity were altered under different N deposition levels,suggesting that the progress of soil carbon emission was accelerated under low levels of N deposition and slowed down under relatively high levels of N deposition in a short period.