增温和施氮对小兴安岭叶凋落物分解的影响

为研究小兴安岭叶凋落物对温度升高、氮沉降及其交互作用的响应。试验采用空间移位方法,进行施氮(LN)、增温(WT)、施氮增温(WLN)和对照(CK)4种处理。结果表明：（1）氮沉降对叶凋落物分解的作用表现为先抑制后逐渐促进,在第1年冻融期后抑制显著(P<0.05);（2）温度升高情况下,第1年生长季较对照相比显著减缓了凋落叶分解(13.8%),显著加快了第2年生长季凋落叶的分解(9.4%);（3）施氮增温共同驱动下凋落物分解情况与增温处理一致,均表现为先抑制后促进;（4）各处理凋落物质量损失率与元素释放率较对照相比皆表现为先抑制后促进,不同处理的叶凋落物质量损失率为LN(55.2%)>WT(54.4%)>WLN(53.4%)>CK(53.2%)。本研究表明：施氮、增温及交互作用对叶凋落物分解均表现为初期抑制、然后加速叶凋落物的分解,与长白山相比,小兴安岭叶凋落物分解对施氮处理的响应更加敏感。

Warming and Nitrogen Application: Effects on Decomposition of Leaf Litter in the Less Khingan Mountains

The paper aims to study the response of leaf litter in the Lesser Khingan Mountains to temperature rise, nitrogen deposition and their interaction. We designed 4 kinds of treatments [nitrogen addition (LN), warming (WT), interaction of nitrogen addition and temperature increase (WLN) and control (CK)] by using the spatial shift method. The results showed that: (1) the effect of nitrogen deposition on leaf litter decomposition was first inhibition and then gradual promotion, and the inhibition was significant after the first year of freezing and thawing (P<0.05); (2) under the condition of temperature increase, the leaf litter decomposition of the first year’s growth season was significantly slowed down (by 13.8%) compared with the control, and the leaf litter decomposition of the second year’s growth season was significantly accelerated (by 9.4%); (3) the litter decomposition under the combined driving of nitrogen and temperature was consistent with the warming treatment, and both of them showed first inhibition and then promotion; (4) the mass loss rate and element release rate of each treatment were firstly inhibited and then promoted compared with the control, and the mass loss rate of leaf litter of different treatments was LN (55.2%)>WT (54.4%)>WLN (53.4%)>CK (53.2%). The study shows that the decomposition of leaf litter is initially inhibited by nitrogen application, temperature increase and interaction, and then accelerated, compared with Changbai Mountains, the decomposition of leaf litter in the Lesser Khingan Mountains is more sensitive to nitrogen addition.