氮沉降对长白山两种主要针叶树种凋落物分解的影响

Effects of Nitrogen Deposition on Litter Decomposition of Two Main Coniferous Tree Species in Changbai Mountain

以长白山2种针叶树种红松和红皮云杉的凋落物作为实验材料,以NH4NO3作为外加氮源,研究不同外源氮输入对凋落物早期分解的影响。在60d实验室培养过程中,对凋落物样品的呼吸速率、样品分解量和样品分解前后基本性质的测定结果进行了分析。结果表明:外源氮输入极大地促进了凋落物CO2和N2O的呼吸;凋落物分解量、残留物中的木质素和N的质量分数随着外源氮梯度增加均显著增加,但残留物C的质量分数并没有发生显著变化;通过对凋落物呼吸和施氮前后凋落物性质的对照分析,得出氮沉降加速了2种凋落物早期的分解过程。

A 60-day ineubatlon experiment in laboratory was conducted to study the effect of external nitrogen （ NH4NO3 ） on the litter decomposition at early stage using Pinus koraiensis and Picea koyamai var. koraiensis grown in Changbai Mountain as experimental materials. The respiration （CO2 and N2O） rate, decomposition rate and the basic property before and after decomposition of eaeh sample were measured by gas chromatography. Result showed that nitrogen input greatly promotes CO2 and N2O respiration. The decomposition amount and the lignin and nitrogen contents of residues increased significandy with external nitrogen increasing, while carbon content of residues did not show an obvious ehange. The comparison of the respiration and property of litter before and after nitrogen input showed that nitrogen deposition promotes the decomposition of Pinus koraiensis and Picea koyamai var. koraiensis litter at early stage.