The resilience of nitrogen fixation in feather moss (Pleurozium schreberi)-cyanobacteria associations after a drying and rewetting cycle
The resilience of nitrogen fixation in feather moss (Pleurozium schreberi)-cyanobacteria associations after a drying and rewetting cycle
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DOI：
10.1007/s11104-013-1984-6
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发表时间：
2014-04
期刊：
影响因子：
4.9
通讯作者：
Kathrin Rousk;Davey L. Jones;T. DeLuca
中科院分区：
文献类型：
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作者：
Kathrin Rousk;Davey L. Jones;T. DeLuca
背景和目标羽毛苔藓-蓝藻群落中的氮（N2）固定是北方生态系统氮的主要来源。然而，由于阳光、温度和降水的每日和每年的波动，苔藓的水分状态会发生显着变化。虽然已经研究了干燥和再润湿对苔藓养分浸出和光合作用的影响，但尚未尝试评估羽毛苔藓固氮的后果。方法我们进行了一项实验，其中我们对羽毛苔藓 Pleurozium schreberi (Brid.) Mitt 样品进行干燥（28°C 下 3 天；田间湿度 <9%）和再润湿样品。固定 N2 的蓝细菌定殖，以评估对 N2 固定的影响。此外，我们还测试了固氮从干燥-再润湿循环中恢复所需的时间。此外，我们评估了 N2 固定如何随乙炔孵育时间（2-65 h）而变化。结果 3 天的干燥期几乎完全消除了苔藓中的 N2 固定（<0.2 μmol m−2h−1）。然而，再润湿后，速率缓慢恢复，再润湿后 5 天达到潮湿（非水胁迫）苔藓的固氮水平。随着乙炔孵育时间的延长，固氮作用显着增加（2 小时孵育时为 0 μmol m−2h−1，65 小时孵育时为 26 μmol m−2h−1）。 结论 尽管在再润湿后氮固定作用重新开始，但恢复缓慢。因此，随着时间的推移，反复的干燥和再润湿循环可以减少苔藓-蓝藻群落中的总氮固定，从而导致系统的总氮输入减少。
Background and aimsNitrogen (N2) fixation in feather moss-cyanobacteria associations is a major source of N for boreal ecosystems. However, mosses experience significant shifts in their moisture status due to daily and yearly fluctuations in sunlight, temperature and precipitation. While the effects of drying and rewetting on nutrient leaching and photosynthesis in mosses have been studied, no attempt has been made to assess the consequences for N2fixation in feather mosses.MethodsWe conducted an experiment in which we dried (3 day at 28 °C; <9 % of field moisture) and rewetted samples of the feather mossPleurozium schreberi(Brid.) Mitt. that is colonized by N2-fixing-cyanobacteria to assess the influence on N2fixation. Further, we tested how long it takes for N2fixation to recover from a drying-rewetting cycle. In addition, we assessed how N2fixation changes with incubation time with acetylene (2–65 h).ResultsA drying period of 3 days almost completely eliminated N2fixation (<0.2 μmol m−2h−1) in the moss. However, rates slowly recovered after rewetting, reaching N2fixation levels of moist (non-water stressed) moss 5 days after rewetting. Nitrogen fixation increased significantly with incubation time with acetylene (0 μmol m−2h−1at 2 h vs. 26 μmol m−2h−1at 65 h incubation).ConclusionsAlthough N2fixation recommenced upon rewetting, the recovery was slow. Thus, recurrent drying and rewetting cycles could reduce total N2fixation in moss-cyanobacteria associations over time, leading to reduced total N input to the system.