Microbial community shifts influence patterns in tropical forest nitrogen fixation.
The role of biodiversity in ecosystem function receives substantial attention, yet despite the diversity and functional relevance of microorganisms, relationships between microbial community structure and ecosystem processes remain largely unknown. We used tropical rain forest fertilization plots to directly compare the relative abundance, composition and diversity of free-living nitrogen (N)-fixer communities to in situ leaf litter N fixation rates. N fixation rates varied greatly within the landscape, and 'hotspots' of high N fixation activity were observed in both control and phosphorus (P)-fertilized plots. Compared with zones of average activity, the N fixation 'hotspots' in unfertilized plots were characterized by marked differences in N-fixer community composition and had substantially higher overall diversity. P additions increased the efficiency of N-fixer communities, resulting in elevated rates of fixation per nifH gene. Furthermore, P fertilization increased N fixation rates and N-fixer abundance, eliminated a highly novel group of N-fixers, and increased N-fixer diversity. Yet the relationships between diversity and function were not simple, and coupling rate measurements to indicators of community structure revealed a biological dynamism not apparent from process measurements alone. Taken together, these data suggest that the rain forest litter layer maintains high N fixation rates and unique N-fixing organisms and that, as observed in plant community ecology, structural shifts in N-fixing communities may partially explain significant differences in system-scale N fixation rates.
Reed
Sasha C
SC
US Geological Survey, Southwest Biological Science Center, Moab, UT 84532, USA. screed@usgs.gov
Townsend
Alan R
AR
Cleveland
Cory C
CC
Nemergut
Diana R
DR
D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D044822:Biodiversity; D003364:Costa Rica; D005308:Fertilizers; D009586:Nitrogen Fixation; D010758:Phosphorus / Q000494:pharmacology; D012230:Rhizobiaceae / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D014197:Trees / Q000235:genetics / Q000382:microbiology*; D014329:Tropical Climate
D005308:Fertilizers; D010758:Phosphorus
Ecology. 2008 Oct;89(10):2924-34
18959329
Microb Ecol. 2006 Oct;52(3):470-9
16909344
Science. 2008 May 9;320(5877):757-8
18467581
Nat Rev Microbiol. 2006 Feb;4(2):102-12
16415926
Ecology. 2006 Feb;87(2):492-503
16637373
ISME J. 2009 Jan;3(1):124-36
18769458
Appl Environ Microbiol. 2005 Dec;71(12):8228-35
16332807
Ecol Lett. 2007 Jul;10(7):628-36
17542941
Appl Environ Microbiol. 1999 Feb;65(2):374-80
9925556
Microb Ecol. 2007 Jan;53(1):110-22
17186150
Nucleic Acids Res. 1997 Dec 15;25(24):4876-82
9396791
Microb Ecol. 2000 Jan;39(1):12-21
10790513
Biotechniques. 2005 Apr;38(4):579-86
15884676
Oecologia. 1997 May;110(4):449-460
28307235
Oecologia. 1989 Jun;79(4):471-474
28313480
Appl Environ Microbiol. 1994 May;60(5):1572-80
8017936
Science. 2008 May 16;320(5878):889-92
18487183
J Biosci Bioeng. 2003;96(4):337-43
16233533
Mol Biol Evol. 2004 Mar;21(3):541-54
14694078
Appl Environ Microbiol. 2004 Feb;70(2):973-83
14766579
Syst Biol. 2005 Dec;54(6):936-47
16338765
Appl Environ Microbiol. 1997 Dec;63(12):4993-5
16535760
Ecology. 2009 Feb;90(2):441-51
19323228
FEMS Microbiol Ecol. 2007 Nov;62(2):161-70
17937673
Appl Environ Microbiol. 2005 Jul;71(7):4117-20
16000830
Nucleic Acids Res. 1997 Sep 1;25(17):3389-402
9254694
Oecologia. 1998 Jan;113(2):179-187
28308195
Ecol Lett. 2007 Feb;10(2):135-45
17257101
Bioinformatics. 2006 Nov 1;22(21):2688-90
16928733
Proc Natl Acad Sci U S A. 2006 Jul 5;103(27):10316-10321
16793925
Plant Physiol. 1968 Aug;43(8):1185-207
16656902