The rapidity of successioni of Ceanothus species in burned-over areas where they are indigenous and the apparent enhancing effect which these species have on the development of other shrubs and ground cover suggests that Ceanothus has a soil-improvement effect and implies the fixation of nitrogen. Nodulation of some species of Ceanothus was observed as early as 1912 (3). Bottomley and also Petr...

A basic problem in biological nitrogen fixation is the distribution of this property among various organisms. Although several decades ago numerous bacteria were reported to fix molecular nitrogen, very few such claims survived because the proof was often based upon an unimpressive increase in visual turbidity or Kjeldahl nitrogen after prolonged culture. The limitation of these methods has bee...

Symbiotic nitrogen (N) fixing trees are absent from old-growth temperate and boreal ecosystems, even though many of these are N-limited. To explore mechanisms that could select against N fixation in N-limited, old-growth ecosystems, we developed a simple resource-based evolutionary model of N fixation. When there are no costs of N fixation, increasing amounts of N fixation will be selected for ...

Biological nitrogen fixation is a very valuable alternative to nitrogen fertilizer. This process will be discussed in the “Biological Nitrogen Fixation” book. A wide array of free-living and associative nitrogen fixing organisms (diazotrophs) will be covered. The most extensively studied and applied example of biological nitrogen fixation is the symbiotic interaction between nitrogen fixing “rh...

The methanogenic Archaea bring a broadened perspective to the field of nitrogen fixation. Biochemical and genetic studies show that nitrogen fixation in Archaea is evolutionarily related to nitrogen fixation in Bacteria and operates by the same fundamental mechanism. At least six nif genes present in Bacteria (nif H, D, K, E, N and X) are also found in the diazotrophic methanogens. Most nitroge...

The incorporation of biological nitrogen fixation into a nondiazotrophic photosynthetic organism provides a promising solution to the increasing fixed nitrogen demand, but is accompanied by a number of challenges for accommodating two incompatible processes within the same organism. Here we present regulatory influence networks for two cyanobacteria, Synechocystis PCC 6803 and Cyanothece ATCC 5...

Legume-Rhizobium nitrogen fixation is dramatically affected under drought and other environmental constraints. However, it has yet to be established as to whether such regulation of nitrogen fixation is only exerted at the whole-plant level (e.g. by a systemic nitrogen feedback mechanism) or can also occur at a local nodule level. To address this question, nodulated pea (Pisum sativum) plants w...

Introduction Conclusions References

This Article is brought to you for free and open access by the Ocean, Earth & Atmospheric Sciences at ODU Digital Commons. It has been accepted for inclusion in OEAS Faculty Publications by an authorized administrator of ODU Digital Commons. For more information, please contact [email protected]. Repository Citation Rahav, Eyal; Herut, Barak; Stambler, Noga; Bar-Zeev, Edo; and Mulholland, ...

Nitrogen is mainly lost from most Australian tropical savanna ecosystems via fire and replenished through symbiotic nitrogen fixation. The frequency and severity of bushfires in Australia, which are common and extensive in tropical savannas, are expected to increase under climate change. Thus the nitrogen loss from tropical savannas can be exacerbated. This research investigates how climate cha...