Characteristics of ammonia-oxidizing bacteria and ammonia-oxidizing archaea abundance in soil organic layer under the subalpine/alpine forest

Abstract

Soil ammonia oxidizers play essential roles in nitrogen cycling in many forest ecosystems. Since the compositions and functions of soil ammonia oxidizer could be suffered from obviously seasonal snow cover and freeze鄄thaw cycles in high latitude / altitude region, there might be significant differences of soil ammonia oxidizer in different periods caused by seasonal freeze鄄thaw cycles. However, little attention has been paid to the variations of soil ammonia oxidizer in different key periods in subalpine / alpine regions. To determine the abundance and distribution of bacterial and archaeal ammonia oxidizers in subalpine and alpine forest, three representative forests (primitive Abies faxoniana forest, PF; mixed A. faxoniana and Betula albosinensis forest, MF, and secondary A. faxoniana forest, SF) were selected in the alipine / subalpine region of Western China. Soils were sampled in soil organic layer (OL) due to the sensitive responses to seasonal

Non-target Effects of Naphthalene on the Soil Microbial Biomass and Bacterial Communities in the Subalpine Forests of Western China

“…Soil microorganisms play important and irreplaceable roles, such as in soil formation, soil fertility maintenance, material circulation and energy flow in forest ecosystems 21,22 . Bacteria are dominant microorganisms in alpine forest soils due to their relatively strong cold resistance 23,24 . In our study, the naphthalene treatment significantly increased the PLFA of the total bacteria, gram-positive (G + ) bacteria, and gram-negative (G − ) bacteria, which was consistent with a previous study 18 , indicating bacterial utilization of naphthalene-derived C. Chemical applications have been increasingly acknowledged to introduce exogenous nutrients, such as C, N and P, which provide an energy source for soil microbes 16 .…”

Soil ecotoxicity assessment of glyphosate use under field conditions: microbial activity and community structure of Eubacteria and ammonia‐oxidising bacteria

“…Ammonia‐oxidising bacteria have low doubling times (20–40 h) coupled with small numbers in most soils . The low temperature and moisture prevailing during sampling and the absence of substrate (no fertiliser applied) may explain the low abundance of AOB . Therefore, we suspect that the existing low population was either in a dormant state or inactive at the time of the experiment, which could have protected cells from glyphosate, and consequently no change in abundance was detected .…”

Effects of snow pack on winter soil nitrogen transformation in two subalpine forests of western sichuan

“…13--0. 12 mg kg -1 d -1 ) 。 说明该区冬季土壤净氮矿化对全年氮矿化有 极大的贡献。 显然,季节性雪被覆盖区土壤氮矿化 与其它地区有所不同,冬季冻融循环和雪被特征可 能有利于土壤氮矿化过程。 另外,最新研究发现,该 区森林冬季低温下仍存在显著的土壤氨氧化细菌和 古菌,微生物生物量的峰值也出现在冬季,这些都暗 示季节性雪被覆盖下高山森林土壤存在显著的矿化 过程 [20] 。 最后,室内实验研究表明,当该区森林土 壤在-5 益 培养后会释放大量铵态氮,且显著高于其 它培养温度下铵态氮( 未发表数据) 。 在高山森林生 态系统中,土壤有效氮( 铵态氮和硝态氮) 是植物生 长发育的重要限制因子 [17] 。 冬季土壤氮矿化及土 壤有效氮含量的提高为春季森林植被的迅速生长提 供了基础条件 [21] 。 但同时,硝态氮的增加及早春冻 融循环和雪被融化为土壤氮淋溶提供了良好的条 件,因此,冬季矿化产生的大量硝态氮也可能通过淋…”

“…2) ,即土壤净氨化量为负值,但培养前后土壤铵态氮 浓度变化相对较小。 先前的研究也发现,该区森林 土壤在冬季末期硝态氮浓度增加而铵态氮浓度降 低 [22] 。 在冬季,土壤经过氨化作用后,大部分铵态 氮可能通过自养细菌的硝化作用转变成硝态氮。 少 量的铵态氮被微生物固持, 或被粘土矿物 质 固 定。 有时,铵态氮也可能通过异养硝化转变成硝态氮 [1] 。 冬季土壤中铵态氮向硝态氮大量转化的现象极为常 见,且土壤中较高含量的氨氧化细菌和古菌也在一 定程度上证实了这一观点 [20,23] 。 另外,在生长季节 到来前,森林土壤中硝态氮会大量积累,这可能与许 多植物通常表现出对硝态氮的偏爱有关,硝态氮是 这些植物获得氮素的主要来源。 森林土壤氮转化主要包括氨化、硝化和微生物 固持 3 个过程 [24] 。 经过整个冬季后,各雪被斑块土 25鄄 26] ;Williams 和 Tonnessen [27] 指出,在 高山地区雪被改变着土壤氮矿化时空格局 [6,8] 容易被微生物分解,从而增强土壤氮矿化速率 [28] 。 反之,一定深度的雪被可以起到较好保温作用,进而 可能促进土壤氮矿化 [29] 。 不同系统和地理区域,能…”