我国现有红壤缓坡地（6~15°）2.1×107hm2，是我国发展粮食和亚热带经济作物及果、林、草的重要基地。湘北红壤丘岗区是我国南方红壤丘陵区农林符合生态系统的典型模块，以农田、果园、灌木丛、森林为主要土地利用类型。以往研究发现，高强度耕作，大量氮肥使用，加上每年5-8月，不均匀、高强度的降雨，造成了坡地土壤氮素严重流失。硝化作用是氮素循环的重要步骤之一，它是通过硝化微生物将NH3氧化为NO3-的一个生物学过程，其中氨氧化微生物将氨（NH3）氧化为亚硝酸（NO2-）的过程该生物学过程的限速步骤。因此，对这一地区关于氨氧化微生物群落结构与丰度同硝化作用和氮素流失的关系引起了氮素循环研究者的关注。
中科院亚热带农业生态研究所土壤微生物组专家以桃源农业生态试验站的坡地长期定位试验为平台，选取其中3种土地利用方式：农作区、自然森林、茶园，通过定量PCR和TRFLP等手段研究了不同土地利用方式对氨氧化细菌（AOB）和氨氧化古菌（AOA）的群落组成的影响以及这些微生物对硝态氮淋失的作用等进行了研究。研究发现，不同土地利用类型对土壤硝化势，AOB和AOA的群落结构，多样性及丰度都有显著影响。茶园和森林区的上坡位和下坡位点AOB和AOA的群落组成均没有显著差异，而农作区下坡位点AOB和AOA的多样性及丰度都显著高于坡上部分（p<0.05）。硝化速率和AOA的多样性和丰度呈显著相关性（p<0.05），而与AOB无显著相关。研究还发现，在这些土地利用类型中，硝酸盐和氨氧化古菌AOA在农作区的流失量最大，并且硝酸盐的流失量与氨氧化古菌的拷贝数呈显著相关性，而且在坡上坡下位点硝态氮的流失量均与AOA的丰度显著相关而与AOB不相关。这些结果说明在不同土地利用类型的酸性红壤坡地中AOA在硝化作用和硝态氮的淋失中起到的作用大于AOB。
相关结果以AOA were more important than AOB in nitrification and NO3-N runoff loss in acidic soils across sloped land use types为题发表在国际期刊Biol Fertil Soils上。
该研究得到国家科技支撑计划（2012CB417106、2012BAD14b03）、“973”计划项目、国家自然科学基金（41271280， 40801098）的资助。（生物谷Bioon.com）
doi:10.1007/s00374-012-0767-1
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Ammonia-oxidizing archaea are more important than ammonia-oxidizing bacteria in nitrification and NO3 −-N loss in acidic soil of sloped land
HongLing Qin, HongZhao Yuan, Hui Zhang, YiJun Zhu, Chunmei Yin, Zhoujin Tan, JinShui Wu, WenXue Wei
As part of a long-term sloped land use experiment established in 1995 at Taoyuan Agro-ecosystem Research Station (111°26′ E, 28°55′ N) in China, soil samples were collected from three land use types, including cropland (CL), natural forest, and tea plantation. Quantitative polymerase chain reaction and terminal restriction fragment length polymorphism were used to determine the abundance and community composition of amoA-containing bacteria (AOB) and archaea (AOA). The results indicate that land use type induced significant changes in soil potential nitrification rate and community composition, diversity, and abundance of AOB and AOA. Both AOB and AOA community compositions were generally similar between upper and lower slope positions (UP and LP), except within CL. The LP soils had significantly (p < 0.05) higher diversity and abundance of both AOB and AOA than in the UP. Potential nitrification rate was significantly correlated (p < 0.05) with diversity and abundance of AOA, but not with AOB. Among land use types, the NO3 − and amoA-containing AOA runoff loss was greatest in CL. Nitrate-N runoff loss was significantly correlated (p < 0.05) with the loss of AOA amoA copies in the runoff water. Furthermore, relationships between NO3 −-N runoff loss and abundance of AOA but not of AOB at both slope positions were significantly correlated (p < 0.05). These findings suggest that AOA are more important than AOB in nitrification and NO3 −-N runoff loss in acidic soils across sloped land use types.
