Nitrogen-fixing tree

Article By:

Wheeler, Chris T. Institute of Biomedical and Life Sciences, Department of Biochemistry and Molecular Biology, University of Glasgow, Glasgow, United Kingdom.

Last reviewed:January 2021

DOI:https://doi.org/10.1036/1097-8542.376250

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• Nitrogen-fixing trees, published June 2014:Download PDF Get Adobe Acrobat Reader

A tree that can convert (fix) atmospheric nitrogen into a form that can be utilized for growth. The ability to convert (fix) atmospheric nitrogen into a form that can be used for plant growth is confined to bacteria and cyanobacteria. Plants fix nitrogen only by virtue of associations with these simple organisms. The best-known associations are the symbioses of Rhizobium bacteria (Fig. 1) with agricultural legumes, such as clovers, peas, and beans, and various legume trees. Rhizobia stimulate the formation of root nodules, which provide a specialized environment within which high rates of nitrogen fixation can occur. Nitrogen fixation not only supports plant growth independent of mineral nitrogen in the soil, but also can improve soil nitrogen status as plant residues, notably leaves and fine roots, decay and are mineralized. See also: Bacteria; Cyanobacteria; Mutualism; Nitrogen; Nitrogen fixation; Root (botany); Soil; Soil chemistry; Soil ecology; Soil fertility; Soil microbiology; Tree; Tree growth

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