台湾桤木林草复合模式根际与非根际氮特征

以台湾桤木+扁穗牛鞭草(模式A)和台湾桤木+自然杂草(模式B)两种模式为研究对象,研究并分析了两模式下台湾桤木、扁穗牛鞭草和自然杂草根际与非根际土的全氮、速效氮、铵态氮及其pH。结果表明:①两种模式下,根际养分均高于非根际养分,表现出明显的正根际效应和强烈的富集作用,在采样月根际土与非根际土间均有显著性差异,但在是从年平均来看并没有差异; ②A模式台湾桤木根际土(AAR)与B模式台湾桤木根际土(BAR),A模式草本根际土(AHR)与B模式草本根际土(BHR),A模式非根际土(AS)与B模式非根际土(BS)进行配对t检验,发现速效氮及铵态氮含量均没有显著性差异(p>0.05); 全氮含量在AAR与BAR、AS与BS之间没有显著性差异(p>0.05),但在AHR与BHR间有显著性差异(p<0.05); ③台湾桤木林内草本的变化对系统氮含量影响较小,只是扁穗牛鞭草改变了台湾桤木对全氮、速效氮和铵态氮的富集态势。

Nitrogen dynamic of rhizosphere and bulk soil in Alnus formosana silvopasture systems

Silvipasture systems, as a major category of agroforestry, has been one of the most important practices for ecosystem rehabilitation in China, because of its diversity of products, great output and sound environment. Alnus formosana+Hemarthria compressa(pattern A)and A. formosana+natural grass(pattern B)were selected to study dynamic of total nitrogen, available nitrogen, ammonium nitrogen and pH value in the rhizosphere soil and bulk soil of both A and B pattern. The results showed that the rhizospheric nutrition was higher than non-rhizospheric nutrition in two patterns, indicating obvious rhizosphere effect and strong enrichment function. The nutrition of both rhizosphere soil and bulk soil had significant difference in every sampling month, but had no significant difference in the average level of whole year. The paired t test was used to analyze A. formosana rhizosphere soil in pattern A(AAR)and A. formosana rhizosphere soil in pattern B(BAR), herbal rhizosphere soil in pattern A(AHR)and herbal rhizosphere soil in pattern B(BHR), bulk soil in pattern A(AS)and bulk soil in pattern B(BS). It was found that there was no significant difference(p>0.05)between available nitrogen and ammonium nitrogen content, and total nitrogen content had no significant difference between AAR and BAR, AS and BS(p>0.05). However, there was significant difference between AHR and BHR(p<0.05). The change of A. formosana forest herbs had low effect on nitrogen dynamic, but H. compressa altered the enrichment situation of total nitrogen, available nitrogen and ammonium nitrogen in A. formosana forest.