额济纳不同植被覆盖类型土壤氮素时空分异特征

量化土壤时空变化对生态系统模型、精准农业和自然资源管理有重要意义。为了更好地控制环境问题,本文把传统统计方法、地统计学方法和地理信息系统三者结合起来,研究了中国西北部额济纳旗(1480 km~2)不同植被覆盖类型土壤氮的时空变化。于2011年与2015年从49个样点采集了98个0~15 cm土壤样品,测量了土壤全氮和硝态氮的含量,比较了不同植被覆盖类型土壤全氮和硝态氮的空间变化和时间变化。结果表明:土壤全氮含量明显受植被覆盖类型影响;土壤全氮平均值变幅为0.259~0.904 g kg~(-1),胡杨林地土壤全氮含量柽柳地土壤全氮含量梭梭地土壤全氮含量;2011年与2015年同一植被覆盖类型下土壤全氮含量差异不显著;2011年胡杨林地、柽柳地、梭梭地土壤硝态氮含量分别为45.185 mg kg~(-1)、76.95mg kg~(-1)、39.335 mg kg~(-1),2015年胡杨林地、柽柳地、梭梭地土壤硝态氮含量分别为2.259 mg kg~(-1)、21.546 mg kg~(-1)、14.554 mg kg~(-1);胡杨林地和柽柳地土壤全氮呈中等强度空间相关性,梭梭地土壤全氮呈强空间相关性;植被覆盖类型明显影响着植被中氮的转移、转化和吸收;研究区土壤氮素含量呈现剧烈的时空变化。

Spatial and Temporal Patterns of Soil Nitrogen Distribution under Different Vegetation Cover Types in Ejina

Quantifying soil spatial-temporal variation is significant in ecological modeling,precision agriculture and natural resource management.The spatial and temporal variability of soil nitrogen (N)under different vegetation cover types in Ejina (1480 km2) in Northwestern China was investigated by using conventional statistics,geostatistics and geographical information system in order to provide information for controlling environmental issues.A total of 98 soil samples (0 to 15 cm) from 49 sites were collected in 2011 and 2015,and analyzed for soil total N and nitrate N.We compared the spatial variations of soil total N and nitrate N under different vegetation cover types as well as the temporal variations in 2011 and 2015.Results showed that the contents of soil total N were deeply affected by vegetation cover types and ranged from 0.259 to 0.904 g kg-1.It decreased in the following order:Populus euphratica ＞ Tamarixspp ＞ Haloxylon ammodendron.No significant difference was found in soil total N between 2011 and 2015 under the same vegetation cover type.However,the average contents of nitrate N in the lands of Populus euphratica,Tamarixspp and Haloxylon ammodendron were 45.185,76.95 and 39.335 mg kg-1 in 2011,respectively,andwere 2.259,21.546 and 14.554 mg kg-1 in 2015,respectively.Soil total N showed a moderate spatial dependence in the lands of Populus euphratica and Tamarixspp,and a strong spatial dependence in the land of Haloxylon ammodendron.The processes of N movement,transformation,and absorption by plant were deeply influenced by vegetation cover types.As a result,great changes of soil N levels at spatial and temporal scales were demonstrated in the studied area.