改变凋落物输入对喀斯特原生乔木林和灌木林土壤氮矿化的影响

Effects of Controlling Litter Input on Soil Nitrogen Mineralization in Karst Primary Arbor Forest and Shrub Forest

以贵州喀斯特原生乔木林和灌木林为研究对象,采用树脂芯法,原位连续测定2种群落类型不同水平凋落物添加下土壤氮矿化/硝化动态特征。结果表明:改变凋落物输入对2群落类型土壤温度产生差异不显著,但均表现为添加大量凋落物L_(20)>添加少量凋落物L5>对照L0。喀斯特原生乔木林和灌木林添加凋落物增加了NO_3^--N含量,降低了NH_4^+-N含量,不同凋落物处理下NH_4^+-N、NO_3^--N含量L0和L_(20)之间均存在显著差异(P<0.05)。不同凋落物输入下2群落类型土壤净矿化速率分别为0.14~0.19和-0.02~0.09 mg/(kg·d),土壤净氨化量/速率均为负值,且随凋落物增加而降低。土壤净硝化量/速率均为正值,且随凋落物增加而增加。原生乔木林无机氮含量、矿化速率、硝化速率均高于灌木林。

Taking Karst primary arbor forest and shrubbery for research objects,the dynamic features of soil N mineralization/nitrification of 2 types of community with different litter input were determined by in-situ continuous incubation by the means of resin-core method. The results showed that there was no significant difference in soil temperature（ P〉 0. 05） between two forest communities when changing the litter input,both following the order of L（20）（large amount） 〉L5（small amount）〉 L0（none）. Litter addition stimulated the increase of NO3--N content,and reduce of the content of NH4＋-N both in Karst primary arbor forest and shrubbery,and there were significant differences in NH4＋-N and NO3--N content between L0 and L（20）（P〈0. 05）. With different litter input the rages of mineralization rate in Karst primary arbor forest and shrubbery were 0. 14- 0. 19 and-0. 02 - 0. 09 mg/（ kg·d） respectively. Net mount/rate of N ammonification were negative,and decreased with increasing litter input; net mount/rate of N nitrification were positive,and increased with increasing litter input. The inorganic N content,rates of net nitrogen mineralization and nitrification in primary arbor forest were all higher than those in shrubbery.