Abstract:

In order to determine the effect of increased nitrogen deposition on total soil respiration of Pinus elliottii forest, and whether increased nitrogen deposition alters the temperature sensitivity of soil respiration, the author used LI-8100 to investigate the response of soil respiration of Pinus elliottii for increased nitrogen deposition, a field experiment with 4 simulated nitrogen deposition levels [0、5、15、30 g N/(m2?a)]. The soil temperature at 10 cm depth and soil moisture at 5 cm depth were recorded at the same time. Results showed that: soil respiration rate had an obvious seasonal change, with the maximum in July and the minimum in January. the annual cumulative soil respiration was [CK 5.28±1.02 t/(hm2?a)] and [LN 4.51±0.64 t/(hm2?a)] and [LN 4.66±0.51 t/(hm2?a)] and [HN 4.20±0.43 t/(hm2?a)]. On average, the mean rate of soil respiration was LN [1.20±0.17 μmol/(m2?s)] and MN [1.24±0.13 μmol/(m2?s)] and HN [1.11±0.11 μmol/(m2?s)], and reduced 16.6%, 13.8% and 22.9% respectively comparing with control level [1.44±0.28 μmol/(m2?s)]. The relationship between soil respiration and soil temperature at 10 cm of Pinus elliottii was significant (P<0.01) (R2=0.6049-0.7557）The Q10 values at 4 different nitrogen treatment levels of Pinus elliottii were LN (1.72) and MN (1.75) and HN (1.79). Compared with which at control level, the Q10 values of Pinus elliottii soil respiration tended to decrease with nitrogen deposition. The relationship between soil respiration and soil moistures at 5 cm depth also were not significant. The results indicated that nitrogen deposition was an important factor in affecting soil CO2 efflux of Pinus elliottii.