三江平原典型小叶章湿地土壤中硝态氮和铵态氮的空间分布格局

Spatial Distribution Patterns of Nitrate Nitrogen and Ammonia Nitrogen in Typical Calamagrostis Angustifolia Wetland Soils of Sanjiang Plain

运用地统计学方法对三江平原典型小叶章湿地土壤中硝态氮(NO3-—N)和铵态氮(NH4+—N)的空间分布格局进行了研究。结果表明,湿地土壤不同土层NO3-—N和NH4+—N含量的变异性差异较大,但均表现为NO3-—N>NH4+—N,原因主要与其物理运移特性的差异有关。两种土壤在不同土层或相同土层中的NO3-—N和NH4+—N含量差异均达到极显著水平(P<0.01);湿地土壤不同土层NO3-—N和NH4+—N的含量分布具有明显空间结构,符合不同变异函数理论模型,结构因素对空间异质性起主导作用,随机因素的影响相对较少。微地貌特征是导致其空间异质性的一个重要随机因素,水分条件和土壤类型则是两个重要结构因素;湿地土壤不同土层NO3-—N和NH4+—N含量的空间变异性均以向洼地中心倾斜方向最大。研究发现,水分条件是导致NO3-—N含量在地势较低处形成低值区的主要原因,干湿交替则是导致NH4+—N含量在地势较低处形成高值区的重要原因。

The spatial distribution patterns of nitrate nitrogen （NO3^--N） and ammonia nitrogen （NH4^＋-N） in typical Calamagrostis angustifolia wetland soils of Saniiang Plain were studied by Geostatistics method. Results showed that the variability of NO3^--N and NH4^＋-N contents in different soil layers had significant difference, with the order of NO3^--N〉NH4^＋-N, and the reasons were mainly correlated with the differences of their physical movement characteristics. Further analysis indicated that the differences of NO3^--N and NH4^＋-N contents in different soil layers or in same soil layer were much significant （P〈0.01）. The distribution of NO3^--N and NH4^＋-N contents in different soil layers had significant spatial structure, which accorded with different semivariogram models. The structure factors had significant effects on there spatial variability, while the effects of random factors were relatively less. Micro-physiognomy characteristic was an important random factor to induce spatial heterogeneity, while water condition and soil type were two important structure factors. The maximum spatial variability of NO3^--N and NH4^＋-N contents in different soil layers were observed in the direction leaning to the depression center. In addition, the studies also indicated that water condition was the main reason to induce the lower NO3^--N content zones to be formed in the lower hypsography of depression, while the alternation of dry and wet was the import reason to induce the higher NH4^＋-N content zones to be formed in the lower hypsography of depression.