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6977054 
Journal Article 
The resilience of nitrogen fixation in feather moss (Pleurozium schreberi)-cyanobacteria associations after a drying and rewetting cycle 
Rousk, K; Jones, DL; Deluca, TH; , 
2014 
1 
Plant and Soil
ISSN: 0032-079X
EISSN: 1573-5036 
SPRINGER 
DORDRECHT 
159-167 
WOS:000333614600010 
Nitrogen (N-2) 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 N-2 fixation in feather mosses.We conducted an experiment in which we dried (3 day at 28 A degrees C; < 9 % of field moisture) and rewetted samples of the feather moss Pleurozium schreberi (Brid.) Mitt. that is colonized by N-2-fixing-cyanobacteria to assess the influence on N-2 fixation. Further, we tested how long it takes for N-2 fixation to recover from a drying-rewetting cycle. In addition, we assessed how N-2 fixation changes with incubation time with acetylene (2-65 h).A drying period of 3 days almost completely eliminated N-2 fixation (< 0.2 mu mol m(-2) h(-1)) in the moss. However, rates slowly recovered after rewetting, reaching N-2 fixation levels of moist (non-water stressed) moss 5 days after rewetting. Nitrogen fixation increased significantly with incubation time with acetylene (0 mu mol m(-2) h(-1) at 2 h vs. 26 mu mol m(-2) h(-1) at 65 h incubation).Although N-2 fixation recommenced upon rewetting, the recovery was slow. Thus, recurrent drying and rewetting cycles could reduce total N-2 fixation in moss-cyanobacteria associations over time, leading to reduced total N input to the system.