The Dynamics Of Soil Nitrogen Mineralization In Different Plant Communities Along An Elevation Gradient Of Wuyi Mountains

Four typical plant communities were selected along an elevation gradient of Wuyi mountains as our study sites i.e. Evergreen Broad-leaf Forest (EBF), Coniferous Forest (CF), Sub-alpine Dwarf Forest (SDF), Alpine Meadow (AM). And we applied lab incubation method to incubate primary soil samples and the method of collecting and analyzing soil samples to study soil nitrogen mineralization and dynamics of soil mineralized nitrogen, respectively. The purposes were to understand the potential influence caused by the global warming and the variation of soil mineralized nitrogen with seasons, soil depths and altitudes of middle subtropical zone on soil nitrogen mineralization. The results indicated:(1)The amount of soil net nitrogen mineralization and net nitrogen mineralization rate were significantly increased with the increasing temperature at same altitude (P<0.05). At same temperature, the amount of soil net nitrogen mineralization and net nitrogen mineralization rate were in order of SDF(1800m) > EBF (500m)> AM (2100m) > CF (1200m) .(2)The Q₁₀ value of soil nitrogen mineralization fluctuated between 1.03 and 1.54. And the Q₁₀ from 15℃to 25℃was higher than that from 5℃to 15℃and that from 25℃to 35℃.(3) The season variation of the amount of soil NH₄⁺-N at four different altitudes and the amount of soil mineralized nitrogen of CF, SDF and AM all showed that: Spring(March, 2008)>Autumn(October, 2007)>Summer(August, 2007)>Winter (December, 2007). The seasonal variation of the amount of soil NO₃^--N in four different altitudes and the amount of soil mineralized nitrogen of EBF all showed that: Autumn > Spring>Summer>Winter.(4)The amount of soil NH₄⁺-N, NO₃^--N and mineralized nitrogen at the same altitude were all decreased with the increasing of the soil depth.(5)The variations of the amount of soil NH₄⁺-N and mineralized nitrogen of the four plant communities along the elevation gradient was the order of AM>SDF>EBF>CF, and soil NO₃^--N was the order of EBF > SDF > AM >CF.