Abstract：
Climate change can pose a significant threat to terrestrial ecosystems by disrupting the circulation of soil nitrogen. However, experimental analyses on the effect of climate change on soil nitrogen cycles and the implications for the conservation of key wildlife species (i.e., the giant panda, Ailuropoda melanoleuca) remain understudied. We investigated the effects of a 1.5 °C, 3 °C, and 4.5 °C temperature increase on nitrogen distribution in different soil layers of bamboo forest via an in-situ experiment and assessed the implications for the growth and survival of arrow bamboo (Bashania faberi), a critical food resource for giant pandas. Our results showed that warming treatments generally increased soil N content, while effects differed between surface soil and subsurface soil and at different warming treatments. Particularly an increase of 1.5 °C raised the subsurface soil NO3-N content, as well as the content of N in bamboo leaves. We found a significant positive correlation between the subsurface soil NO3-N content and the N content of arrow bamboo. An increase of 3-4.5 °C raised the content of total N and NO3-N in the surface soil and led to a reduction in the total aboveground biomass and survival rate of arrow bamboo. Limited warming (e.g., the increase of 0-1.5 °C) may promote the soil N cycle, raise the N-acetylglucosaminidase (NAG) enzyme activity, increase NO3-N in subsurface soil, increase the N content of bamboo, and boost the biomass of bamboo - all of which could be beneficial to giant panda survival. However, higher warming (e.g., an increase of 3-4.5 °C) resulted in mass death of bamboo and a large reduction in aboveground biomass. Our findings provide a cautiously optimistic scenario for bamboo forest ecosystems under low levels of warming over a short period of time, but risks from higher levels of warming may be serious, especially considering the unpredictability of global climatic change.
摘要：
气候变化可以通过破坏土壤氮的循环对陆地生态系统构成重大威胁。然而,关于气候变化对土壤氮循环的影响以及对关键野生动物物种保护的影响的实验分析(即，大熊猫,Ailuropodamelanoleuca）仍未得到充分研究。我们研究了1.5°C的影响，3°C,通过原位实验，增加4.5°C温度对竹林不同土壤层氮素分布的影响，并评估了箭竹（Bashaniafaberi）的生长和存活的影响，大熊猫的重要食物资源。我们的结果表明，增温处理通常会增加土壤N含量，而表层土壤和地下土壤以及不同增温处理的影响不同。特别是1.5°C的增加增加了地下土壤NO3-N的含量，以及竹叶中N的含量。我们发现地下土壤NO3-N含量与箭竹的N含量之间存在显着正相关。增加3-4.5°C会增加表层土壤中总N和NO3-N的含量，并导致地上总生物量和箭竹的成活率降低。有限的变暖(例如，0-1.5°C)的增加可能促进土壤氮循环，提高N-乙酰氨基葡萄糖苷酶（NAG）的酶活性，增加地下土壤中的NO3-N，增加竹子的氮含量，并增加竹子的生物量-所有这些都可能有利于大熊猫的生存。然而,更高的变暖(例如，3-4.5°C）的升高导致竹子大量死亡，地上生物量大量减少。我们的发现为短时间内低水平变暖的竹林生态系统提供了谨慎乐观的情景，但是更高水平的变暖可能会带来严重的风险，特别是考虑到全球气候变化的不可预测性。
