摘要:作为影响全球变化的主要因子之一，氮沉降对生态系统生物地球化学循环有重要的影响。细菌作为土壤生态系统物质循环的关键参与者，是土壤生态系统变化的敏感指标，在氮沉降对生态系统影响过程中发挥不可忽视的作用。模拟2种施氮方式（SAN：土表施氮，LAN：叶面施氮）和3种施氮量（5.6、15.6、20.6 g N m^-2 a^-1），运用PCR-DGGE技术，分析不同施氮方式和施氮量对两种盆栽植物马尾松（Pinus massoniana Lamb.）和木荷（Schima superba Gardn.et Champ.）幼苗土壤细菌多样性和群落组成的影响。结果表明：不同氮添加方式下，土壤细菌多样性和群落组成对氮添加的响应不同，并受到季节的影响。在雨季，LAN处理木荷土壤细菌多样性高于SAN处理；而旱季，LAN处理两种幼苗根系土壤细菌多样性均高于SAN处理。LAN处理条件下，马尾松土壤Acidobacteria_Gp1相对丰度在旱季和雨季均显著高于SAN处理（P<0.05）。在雨季，马尾松LAN处理土壤Alphaproteobacteria相对丰度显著低于SAN处理（P<0.05），旱季没有显著差异（P>0.05）。氮添加能够提高木荷土壤细菌多样性，提高马尾松土壤变形菌门的相对丰度。旱季施氮还能够提高马尾松土壤Actinobacteria相对丰度，降低木荷土壤酸杆菌门的相对丰度。土壤细菌群落变化与土壤pH显著相关（P<0.05），木荷土壤细菌群落还受到土壤NH₄⁺-N含量的显著影响（P<0.05）。



Abstract:Nitrogen (N) deposition, an important global change factor, plays a great role in biogeochemical cycling in the ecosystem. As an important participant in the material cycle of soil ecosystems, bacteria are sensitive to changes in the soil ecosystem and play an important role in the effect of N deposition on soil ecosystems. A pot experiment was designed with two different N application methods (SAN: soil surface spraying and LAN: leaf surface spraying) and three N application levels (5.6 g N m^-2a^-1, 15.6 g N m^-2a^-1, and 20.6 g N m^-2a^-1) to evaluate the effects of N application on soil bacterial diversity and community of Pinus massoniana Lamb. and Schima superba Gardn. et Champ. seedlings using polymerase chain reaction-denaturing gradient gel electrophoresis techniques. The results showed that the responses of soil bacteria diversity and community to N application were different between the SAN and LAN treatments and they were influenced by season. During the wet season, the soil bacterial diversity of S. superba in the LAN treatment was richer than that for the SAN treatment, which was consistent with the variation trend of the soil bacterial diversity of the P. massoniana and S. superba seedling roots during the dry season. Compared to the SAN treatment, the relative abundance of soil Acidobacteria_Gp1 of P. massoniana was significantly higher in the LAN treatment than that in the SAN treatment (P<0.05). The relative abundance of soil Alphaproteobacteria of P. massoniana was significantly lower in the LAN treatment than that in the SAN treatment for the wet season (P<0.05); however, it was not significantly different for the dry season (P>0.05). N application increased the bacterial diversity of the S. superba soil and the relative abundance of Proteobacteria in the P. massoniana soil. N application stimulated the relative abundance of soil Actinobacteria of P. massoniana; however, it decreased the relative abundance of soil Acidobacteria of S. superba. The soil bacterial community was significantly correlated with soil pH (P<0.05) and was significantly influenced by soil NH₄⁺-N content (P<0.05) in the S. superba soil.





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