Scaling from Molecules to Ecosystems

All living organisms require nitrogen, and a single
process biological nitrogen fixation accounts for
more than 97% of natural nitrogen inputs into Earth s
ecosystems. To date, most nitrogen fixation research
has focused on the symbiotic nitrogen fixation
occurring via the structured relationship of
particular bacteria and plant roots. Yet free-living
nitrogen fixation, the nitrogen fixation occurring
outside of this symbiosis, may represent the dominant
source of biologically-available nitrogen to a
variety of ecosystems. Here we explored free-living
nitrogen fixation controls, ranging from the effect
of fertilization on nitrogen inputs to the role of
microbial nitrogen-fixer community structure in
regulating nitrogen fixation rates. We found that
free-living nitrogen fixation was a dynamic process
that supplied diverse ecosystems with nitrogen, and
that we could elucidate multiple controls over this
important process.

Autorentext

These authors aim to study how terrestrial ecosystems work byexploring the ways in which elements like carbon, nitrogen andphosphorus cycle within the systems. They study both abioticand biotic controls over this biogeochemical cycling, and oftenfocus on how the structure and activity of microbial communitieshelp drive ecosystem function.

Klappentext

All living organisms require nitrogen, and a singleprocess - biological nitrogen fixation - accounts formore than 97% of natural nitrogen inputs into Earth'secosystems. To date, most nitrogen fixation researchhas focused on the symbiotic nitrogen fixationoccurring via the structured relationship ofparticular bacteria and plant roots. Yet free-livingnitrogen fixation, the nitrogen fixation occurringoutside of this symbiosis, may represent the dominantsource of biologically-available nitrogen to avariety of ecosystems. Here we explored free-livingnitrogen fixation controls, ranging from the effectof fertilization on nitrogen inputs to the role ofmicrobial nitrogen-fixer community structure inregulating nitrogen fixation rates. We found thatfree-living nitrogen fixation was a dynamic processthat supplied diverse ecosystems with nitrogen, andthat we could elucidate multiple controls over thisimportant process.