我國(guó)現(xiàn)有紅壤緩坡地（6~15°）2.1×107hm2,，是我國(guó)發(fā)展糧食和亞熱帶經(jīng)濟(jì)作物及果、林、草的重要基地,。湘北紅壤丘崗區(qū)是我國(guó)南方紅壤丘陵區(qū)農(nóng)林符合生態(tài)系統(tǒng)的典型模塊,，以農(nóng)田,、果園、灌木叢,、森林為主要土地利用類型,。以往研究發(fā)現(xiàn)，高強(qiáng)度耕作,，大量氮肥使用,，加上每年5-8月，不均勻,、高強(qiáng)度的降雨,，造成了坡地土壤氮素嚴(yán)重流失。硝化作用是氮素循環(huán)的重要步驟之一,，它是通過(guò)硝化微生物將NH3氧化為NO3-的一個(gè)生物學(xué)過(guò)程,，其中氨氧化微生物將氨（NH3）氧化為亞硝酸（NO2-）的過(guò)程該生物學(xué)過(guò)程的限速步驟。因此,，對(duì)這一地區(qū)關(guān)于氨氧化微生物群落結(jié)構(gòu)與豐度同硝化作用和氮素流失的關(guān)系引起了氮素循環(huán)研究者的關(guān)注,。
中科院亞熱帶農(nóng)業(yè)生態(tài)研究所土壤微生物組專家以桃源農(nóng)業(yè)生態(tài)試驗(yàn)站的坡地長(zhǎng)期定位試驗(yàn)為平臺(tái)，選取其中3種土地利用方式：農(nóng)作區(qū),、自然森林,、茶園，通過(guò)定量PCR和TRFLP等手段研究了不同土地利用方式對(duì)氨氧化細(xì)菌（AOB）和氨氧化古菌（AOA）的群落組成的影響以及這些微生物對(duì)硝態(tài)氮淋失的作用等進(jìn)行了研究,。研究發(fā)現(xiàn),，不同土地利用類型對(duì)土壤硝化勢(shì)，AOB和AOA的群落結(jié)構(gòu),，多樣性及豐度都有顯著影響,。茶園和森林區(qū)的上坡位和下坡位點(diǎn)AOB和AOA的群落組成均沒有顯著差異，而農(nóng)作區(qū)下坡位點(diǎn)AOB和AOA的多樣性及豐度都顯著高于坡上部分（p<0.05）,。硝化速率和AOA的多樣性和豐度呈顯著相關(guān)性（p<0.05）,，而與AOB無(wú)顯著相關(guān)。研究還發(fā)現(xiàn),，在這些土地利用類型中,，硝酸鹽和氨氧化古菌AOA在農(nóng)作區(qū)的流失量最大，并且硝酸鹽的流失量與氨氧化古菌的拷貝數(shù)呈顯著相關(guān)性，而且在坡上坡下位點(diǎn)硝態(tài)氮的流失量均與AOA的豐度顯著相關(guān)而與AOB不相關(guān),。這些結(jié)果說(shuō)明在不同土地利用類型的酸性紅壤坡地中AOA在硝化作用和硝態(tài)氮的淋失中起到的作用大于AOB,。
相關(guān)結(jié)果以AOA were more important than AOB in nitrification and NO3-N runoff loss in acidic soils across sloped land use types為題發(fā)表在國(guó)際期刊Biol Fertil Soils上。
該研究得到國(guó)家科技支撐計(jì)劃（2012CB417106,、2012BAD14b03）,、“973”計(jì)劃項(xiàng)目、國(guó)家自然科學(xué)基金（41271280,， 40801098）的資助,。（生物谷Bioon.com）
doi:10.1007/s00374-012-0767-1
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PMID:
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.
