浙江省宁波市土壤有机质的时空变异特征

Spatio-Temporal Variability Characteristics of Soil Organic Matter in Ningbo City,Zhejiang Province

运用地统计学方法分析了2007年浙江省宁波市土壤w(有机质)的空间分布规律,并比较了1987与2007年城区的土壤w(有机质)的时间变化特征.结果表明:壤土、砂土、黏土中的黏土质地w(有机质)最高;针叶林、阔叶林、草甸、灌丛、农作物、竹林植被覆盖类型中的针叶林w(有机质)最高;水田、旱田、林地、草场、未利用地土地利用方式中草场的w(有机质)最高;潮土、水稻土、红壤、黄壤、紫色土、滨海盐土、粗骨土土壤类型中的黄壤w(有机质)最高.经西北—东南向的变异函数分析得到研究区土壤w(有机质)空间分布呈现城区高、周围低的规律,空间自相关距离约500 m.1987—2007年,水田采样点的土壤w(有机质)显著减小.配对数据T检验的结果显示,北仑区的土壤w(有机质)显著变化,耕作方式由水田变为旱田是土壤w(有机质)减小的主要原因.

Geostatistics were used to explore the spatial variability characteristics of soil organic matter（SOM） in Ningbo City,Zhejiang province in 2007,as well as the temporal variability characteristics between 1987 and 2007 in the urban areas. The results demonstrated that clay contained higher SOM than loam soil and sandy soil;coniferous forest contained higher SOM than shrubs,meadow,hardwood forest,crop and bamboo forest;grassland contained higher SOM than paddy fields,dry land,forestland,and unused land;and,yellow soil contained higher SOM than alluvial soil,red soil,paddy soil,purple soil,coastal saline soil and regosols.The variogram model in the NW-SE direction showed a decreasing trend of SOM from the urban area to the suburbs with a range of 500 m spatial correlation.During the two decades, there was an apparent decrease of SOM in paddy fields,and Pair-Sample T test showed there was an apparent change of SOM in the Beilun district,the main reason of which was the transformation of farming mode from paddy fields to dry land.