Open AccessImpacts of warming and fertilization on nitrogen‐fixing microbial communities in the Canadian High Arctic
Author(s) -
Deslippe Julie R.,
Egger Keith N.,
Henry Greg H.R.
Publication year - 2005
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1016/j.femsec.2004.12.002
Subject(s) - biology , arctic , human fertilization , nitrogen , nitrogen fixation , nitrogen cycle , ecology , nitrogen fertilizer , global warming , the arctic , climate change , agronomy , oceanography , bacteria , fertilizer , genetics , physics , quantum mechanics , geology
The impacts of simulated climate change (warming and fertilization treatments) on diazotroph community structure and activity were investigated at Alexandra Fiord, Ellesmere Island, Canada. Open Top Chambers, which increased growing season temperatures by 1–3 °C, were randomly placed in a dwarf‐shrub and cushion‐plant dominated mesic tundra site in 1995. In 2000 and 2001 20N:20P 2 O 5 :20K 2 O fertilizer was applied at a rate of 5 g m −2 year −1 . Estimates of nitrogen fixation rates were made in the field by acetylene reduction assays (ARA). Higher rates of N fixation were observed 19–35 days post‐fertilization but were otherwise unaffected by treatments. However, moss cover was significantly positively associated with ARA rate. NifH gene variants were amplified from bulk soil DNA and analyzed by terminal restriction fragment length polymorphism analysis. Non‐metric multidimensional scaling was used to ordinate treatment plots in nifH genotype space. NifH gene communities were more strongly structured by the warming treatment late in the growing season, suggesting that an annual succession in diazotroph community composition occurs.