植被恢复对旱区表土颗粒中有机碳和氮分布的影响

The influence of vegetation recovery on organic carbon and nitrogen distribution in surface soil particle of dry area

采用物理分离的方法，获得植被恢复过程中不同土壤粒径的组分，并进行了各组分中有机碳和全氮含量的测定．结果表明，黏粉粒（〈0．05mm）含量的增加和沙粒（0．25—0．1mm）含量的减少，共同导致表层土壤质地细粒化．土壤质地的细粒化伴随着有机碳和氮的固存效应，该效应在固沙20年以后效果显著（P＜0．05）．沙粒（〉0．1mm）含量与有机碳和氮含量呈显著负相关（P＜0．001），而极细沙（0．1～0．05mm）和黏粉粒（〈0．05mm）含量与有机碳和氮含量均呈显著正相关（P〈0．001）．产生上述结果的原因是，表层土壤颗粒组成中各粒径结合的有机碳和氮含量均增加相关，其贡献程度为黏粉粒〉极细沙〉沙粒．植被恢复过程中，表层土壤中黏粉粒含量的增加对维持有机碳和氮固存起着主要的作用，土壤的物理稳定也因为土壤中有机质和黏粉粒含量的增加而增大。

Adopting the physical separation technique to gain different soil particle size component in the process of vegetation recovery, and determine the contents of organic carbon and total nitrogen in each component. The increase of the content of silt and clay （〈0.05mm） and the decrease of the content of sand grains （0.25～0.1mm） led jointly the fining of soil texture in surface soil layer; the fining of soil texture was accompanied with the fixed existing effect of organic carbon and nitrogen, with marked effect （P〈0.05） after 20 years of fixed sand. The content of sand grains（〉0.1mm） in topsoil exhibits a significant negative correlation with organic carbon and nitrogen contents （P〈0.01）, but the contents of very fine sand （0.1～0.05mm） and the content of silt＋clay （〈0.05mm） showed marked positive correlation （P〈0.001）. The reason of the above results was that the contents of organic carbon and nitrogen combined with each particle size in surface soil layer all increased in relation and their contribution degrees were in the order： silt and clay〉very fine sand 〉 sand grains. The increase in the silt and clay content surface soil layer in the vegetation restoration processes played an important role to the fixed existing of organic carbon, and nitrogen, and the soil physical stability also increased with the increase in the organic matter content and silt and clay contents in the soil.