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以江苏省扬州市江都区女贞人工林为对象,研究了密度调控对其土壤N2O排放通量的影响。结果表明,3种密度下土壤N2O排放通量均是秋季和春季较高,冬季最低。秋季时,3种密度下N2O排放通量大小比较为4225株·hm-2(9.985μg m-2·h-1)>1050株·hm-2(8.195μg·m-2·h-1)>2275株·hm-2(6.971μg·m-2·h-1),但各密度间差异不显著(P>0.05)。冬季时,N2O排放通量下降明显,其中4225株·hm-2密度(-10.355μg·m-2·h-1)和2275株·hm-2密度(-2.716μg·m-2·h-1)均为负值,且两者明显低于1050株·hm-2密度下N2O排放通量(2.629μg·m-2·h-1)。春季伴随着温度的回升,各密度下N2O排放通量均显著增加,并达到4个季度中的最高值,其中2275株·hm-2密度下排放通量最低(7.513μg·m-2·h-1),且与4225株·hm-2(11.839μg·m-2·h-1)和1050株·hm-2(12.175μg·m-2·h-1)密度间差异达到极显著水平(P<0.01)。夏季时,3种密度下N2O排放通量分别为4225株·hm-2(3.201μg·m-2·h-1),2275株·hm-2(7.658μg·m-2·h-1)和1050株·hm-2(6.804μg·m-2·h-1),各密度间差异并不显著(P>0.05)。土壤N2O排放通量与土温呈极显著正相关(P<0.01),与NH4+-N和NO3--N含量间则呈极显著负相关(P<0.01)。土壤氮矿化速率与N2O排放通量也呈线性相关极显著(P<0.01),说明密度调控作用于土壤因子,并对N2O排放产生明显影响。
The effects of density control on soil N2O emission fluxes were studied in the forest of Ligustrum przewalskii in Jiangdu District, Yangzhou City, Jiangsu Province. The results showed that N2O flux of soils at all three densities was higher in autumn and spring and lowest in winter. In autumn, the fluxes of N2O at the three densities were 4225 plants · hm-2 (9.985μg m-2 · h-1)> 1050 plants · hm-2 (8.195μg · m-2 · h-1) > 2275 plants · hm-2 (6.971μg · m-2 · h-1), but there was no significant difference among different densities (P> 0.05). In winter, N2O emission flux decreased significantly, of which 4225 plants · hm-2 density (-10.355μg · m-2 · h-1) and 2275 plants · hm-2 density (-2.716μg · m- 1) were both negative, and both of them were significantly lower than 1050 N2O flux (2.629 μg · m-2 · h-1) at the density of hm-2. In spring, with the temperature rising, the fluxes of N2O increased significantly at all densities and reached the highest level in four quarters, of which the discharge flux at the density of 2275 plants · hm-2 was the lowest (7.513 μg · m -2 · h -1), and reached the extremely significant difference with the density of 4225 plants · hm-2 (11.839μg · m-2 · h-1) and 1050 plants · hm-2 (12.175μg · m-2 · h-1) (P <0.01). In summer, the fluxes of N2O at the three densities were 4225 plants · hm-2 (3.201μg · m-2 · h-1) and 2275 plants · hm-2 (7.658μg · m-2 · h-1) And 1050 plants · hm-2 (6.804 μg · m-2 · h-1), respectively. There was no significant difference between the densities (P> 0.05). There was a significant positive correlation between soil N2O flux and soil temperature (P <0.01), but negatively correlated with NH4 + -N and NO3 - N (P <0.01). Soil nitrogen mineralization rate and N2O emission flux also showed a significant linear correlation (P <0.01), indicating that the role of density regulation on soil factors and N2O emissions have a significant impact.