NITROGEN IN 2 CONTRASTING ANTARCTIC BRYOPHYTE COMMUNITIES
NITROGEN IN 2 CONTRASTING ANTARCTIC BRYOPHYTE COMMUNITIES
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DOI：
10.2307/2260537
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发表时间：
1987-03-01
影响因子：
5.5
通讯作者：
CHRISTIE, P
中科院分区：
文献类型：
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作者：
CHRISTIE, P
(1)18个月，从1978年10月到1980年2月，进行了研究的两个对比的苔藓为主的社区Signy岛，南奥克尼群岛[南极]的氮的输入和输出：一个半ombrogenous干草皮和sologenous湿地毯。(2)干草皮比湿地毯酸性更强（pH 4.3对5.0），并且具有更低的含水量（564对869%，干重）。单位干重的总氮，磷和钾的草皮浓度（0.79，0.07和0.11%，分别）比湿地毯（2.17，0.53和0.16%，分别）。夏季可提取无机氮浓度在干草皮中较低（0.22 v.0.50 mg n（100 g）-1干重泥炭），但差异不显著。1979年10月覆盖在干草皮和湿地毯上的累积冬雪分别含有39和42 μ g N l-1。这些雪融化了，4周后积累的后续积雪分别含有113和83 μ g N l-1。这些较高的氮浓度可能是由于初夏附近企鹅的活动。1979年12月，在干燥的草皮和湿的地毯上，融水和场地表面上的水池分别含有230和165 μ g N l-1。(3)硫酸盐还原菌（脱硫弧菌和脱硫肠状菌）和梭菌的数量非常低，即使在含有150个硫酸盐还原菌和290个梭菌（100 g）-1干重泥炭的湿地毯中也是如此。因此，虽然这些细菌的培养物显示出乙炔还原活性，但它们的丰度非常低，表明异养固氮在这些群落中不太可能是重要的，特别是因为没有检测到固氮菌。没有发现硝化细菌，但大量的蛋白水解和硝酸盐呼吸细菌和少量的硝化细菌发生。所有的异养菌群研究更丰富的湿地毯比在干燥的草坪。(4)来自这两个地点的蓝细菌Nostoc muscorum的培养物在15 ℃下显示出高的乙炔还原活性。C.在15 ℃下，来自干草皮和湿地毯的苔藓嫩枝分别以0.12和0.14 mmol g-1干重h-1的速率产生乙烯。C.附生蓝藻可能是主要的固氮生物。(5)计算无机氮输入生物固氮和降水（包括企鹅活动）分别为45.9和64.1毫克米-2年-1（干草皮）和192.4和65.1毫克米-2年-1（湿地毯）。
(1) For 18 months, from October 1978 until February 1980, studies were conducted on the nitrogen inputs and outputs of two contrasting moss-dominated communities on Signy Island, South Orkney Islands [Antarctic]: a semi-ombrogenous dry turf and a soligenous wet carpet. (2) The dry turf was more acidic than the wet carpet (pH 4.3 v. 5.0) and had a lower water content (564 v. 869%, dry wt basis). The turf had lower concentrations per unit dry weight of total nitrogen, phosphorus and potassium (0.79, 0.07 and 0.11%, respectively) than the wet carpet (2.17, 0.53 and 0.16%, respectively). Summer concentrations of extractable inorganic nitrogen were lower in the dry turf (0.22 v. 0.50 mg n (100 g)-1 dry wt peat), but the difference was not significant. Accumulated winter snow overlying the dry turf and wet carpet in October 1979 contained 39 and 42 .mu.g N l-1, respectively. This snow melted and subsequent snow cover, which had accumulated 4 weeks later, contained 113 and 83 .mu.g N l-1, respectively. These higher nitrogen concentrations were probably due to early summer activity by nearby penguins. Melt-water and pools on the surface of the sites in December 1979 contained 230 and 165 .mu.g N l-1 on the dry turf and wet carpet, respectively. (3) Numbers fo sulphate-reducing bacteria (Desulfovibrio and Desulfotomaculum) and clostridia were very low, even in the wet carpet which contained 150 sulphate-reducers and 290 clostridia (100 g)-1 dry wt peat. Thus, although cultures of these bacteria showed acetylene reduction activity, their very low abundance indicates that heterotrophic dinitrogen fixation is unlikely to be important in these communities, especially since no azotobacters were detected. No nitrifying bacteria were found, but substantial numbers of proteolytic and nitrate-respiring bacteria and a small number of denitrifying bacteria occurred. All heterotrophic groups studied were more abundant in the wet carpet than in the dry turf. (4) Cultures of the cyanobacterium Nostoc muscorum from both sites showed high acetylene reduction activity at 15.degree. C. Moss shoots from the dry turf and wet carpet produced ethylene at rates of 0.12 and 0.14 mmol g-1 dry wt h-1, respectively, at 15.degree. C. Epiphytic cyanobactria were probably the main nitrogen-fixing organisms present. (5) Calculated inorganic nitrogen inputs from biological nitrogen fixation and precipitation (including penguin activity) were 45.9 and 64.1 mg m-2 year-1 (dry turf) and 192.4 and 65.1 mg m-2 year-1 (wet carpet).