In the recent decades, human activities have more influence on the global ecological cycle, leading to the atmospheric change and the increases in N deposition. Litter decomposition is a crucial process in the cycling of ecosystem elements. Taking the Quercus liaotungensis in Beijing west-mountain area as the research object, a field experiment was conducted to investigate the responses of litter decomposition to simulated N deposition. This provides reference to get a better understanding of nitrogen deposition on litter decomposition process of temperate forest. This paper indicated how three different N forms (NO3--N, NH4+-N and mixed N) and three N input levels (Control N 0 kg·hm-2·a-1、low N 50 kg·hm-2·a-1 and high N 150 kg·hm-2·a-1) effect on litter disposition. Within 2 years, we have investigated and analyzed the dynamic changes of mass loss, C&N content and w(C)/w(N) value during the litter decomposition process. The data suggested that, three different levels of N input all slowed the litter decomposition rate inordinately. With the increase of N addition, the litter decomposition rate, compared with the contrast, has slowed 9.88%(low nitrate N), 15.02%(high nitrate N), 11.46%(low ammonium N), 14.62%(high ammonium N), 13.04%(low mixed N) and 16.20%(high mixed N) respectively. There is significant difference among different forms or different levels of N addition. They all play a significant role in promoting the N content in litter (P=0.061, P=0.087), in which mixed N addition has the most significant effect on the N content in the litter (P=0.044). But in the process of decomposition, the treatments had no significant effect on the C content in litter. Different levels of N addition significantly reduced the w(C)/w(N)ratio in litter. The different levels and types of N addition have significant interaction effect on the litter w(C)/w(N) values (P=0.011). After simulated nitrogen deposition, the analysis of the litter residual rate and property lead to the conclusion that nitrogen deposition inhibits temperate forest litter decomposition.%森林凋落物的分解是生态系统养分循环的重要过程，以北京西山地带性植被栎树林（辽东栎：Quercus liaotungensis）为对象，主要研究温带森林植物凋落物分解对模拟氮沉降的响应，为更好地了解氮沉降对温带森林地区凋落物的分解过程提供参考。通过模拟氮沉降，研究不同形态氮（硝态氮、铵态氮和混合态氮）和不同水平氮沉降（对照0 kg·hm-2·a-1、低氮处理50 kg·hm-2·a-1和高氮处理150 kg·hm-2·a-1）对凋落物分解的影响，在2年的时间内调查分析了凋落物分解过程中质量损失动态和碳（C）、N含量及w(C)/w(N)比值的变化。研究结果表明，氮沉降均使凋落物分解速率减缓，且随氮沉降剂量增加，凋落物分解速率相比对照分别减慢了9.88%（硝态氮低氮）、15.02%（硝态氮高氮）、11.46%（铵态氮低氮）、14.62%（铵态氮高氮）、13.04%（混合态氮低氮）和16.20%（混合态氮高氮）。且不同氮沉降类型、不同氮沉降水平间差异显著。不同形态、不同水平的氮沉降显著地增加了凋落物N含量（P=0.061，P=0.087），其中混合态氮沉降对凋落物中N素含量增加最显著（P=0.044）。但在分解过程中，各处理均未对凋落物C含量产生显著影响。不同水平的氮沉降显著降低了凋落物的w(C)/w(N)比值，而且不同类型不同水平氮沉降对凋落物w(C)/w(N)比值具有显著的交互作用（P=0.011）。综上所述，通过对模拟氮沉降后凋落物残留率等的变化分析，得出氮沉降对温带森林凋落物的分解产生了抑制作用。
展开▼
