You are not currently logged in.
Access your personal account or get JSTOR access through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Nitrogen-Fixation and Nutrient Relations in Savanna Woodland Trees (Tanzania)
Journal of Applied Ecology
Vol. 23, No. 2 (Aug., 1986), pp. 675-688
Published by: British Ecological Society
Stable URL: http://www.jstor.org/stable/2404045
Page Count: 14
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
(1) Foliar nutrient relations of non-N2-fixing and potentially N2-fixing (species found to form root nodules elsewhere) deciduous trees at five savanna woodland sites in Tanzania were compared with data on soft nutrients. The study comprised forty-eight species-site combinations. (2) Nodulation and nitrogenase activity were confirmed in mature specimens of twelve of the fourteen potentially N2-fixing legume species studied. The twelve species belong to the genera Acacia, Dalbergia, Dichrostachys, Entada, Pericopsis, Pterocarpus and Xeroderris. (3) Non-N2-fixing species had, on average, a 0.0007 atom% higher 15N abundance in their leaves than potentially N2-fixing species, which had a N isotope composition close to the atmospheric. The result supported the 15N natural abundance method as an indicator of N2-fixation only in principle, as the method did not allow statements about single species. (4) The N concentration in leaves at the end of the rainy season was, on average, substantially higher in potentially N2-fixing species than in non-N2-fixing species at all sites (2.71% as compared to 1-63% of dry mass). There were no differences in the concentrations of K, Mg, Ca, S, Mn and B between the two groups at any of the sites. (5) Phosphorus in leaves of non-N2-fixing species increased considerably in relation to N, concurrently with a similar change in the soils at four sites with miombo (Brachystegia-Julbernardia) woodland vegetation, while there were no differences between sites in potentially N2-fixing species. (6) The concentrations of nutrients in leaves and the relations between them indicate that N limits growth in non-N2-fixing species at most sites, while P is limiting in N2-fixing species. Comparisons of the relation between P and N in non-N2-fixing and N2-fixing species is proposed as an indicator of the availability of these nutrients in the soft, provided that no other nutrient is limiting.
Journal of Applied Ecology © 1986 British Ecological Society