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Legumes native to longleaf pine savannas exhibit capacity for high N 2 ‐fixation rates and negligible impacts due to timing of fire
Author(s) -
Hiers J. K.,
Mitchell R. J.,
Boring L. R.,
Hendricks J. J.,
Wyatt R.
Publication year - 2003
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1046/j.1469-8137.2003.00679.x
Subject(s) - biology , fixation (population genetics) , growing season , legume , nitrogen fixation , botany , agronomy , zoology , biochemistry , genetics , bacteria , gene
Summary• N 2 fixation rates of three legume species and the impact of fire regime are reported. • Summer, winter, and no burn treatments were applied. N 2fixation rates (15 N isotope dilution) and C trade‐offs with flowering and fine root turnover were examined in response to season of burn. • TephrosiaandCentrosemahad uniformly high percentage Ndfaacross all treatments (74–92% Ndfa), whereasRhynchosiashowed limited N2fixation activity (18% and 0%). No evidence for decreased N2fixation due to loss of leaf area following growing season burns was found. Moreover, no consistent evidence for decreased N2 fixation with greater flowering or fine root turnover was observed. • Despite species differences in response to fire regime, the following patterns emerged: when increased N 2fixation is associated with decreased growth rates, legumes show limited N2fixation rates (as seen inRhynchosia). Alternatively, if greater N2fixation is related to increased growth rates, then legumes experience C limitations to N2fixation only in small individuals or during periods of rapid growth (as inCentrosema). Reproduction may influence N2‐fixation, but, as in the case ofTephrosia , the relationship was positive, opposite to patterns indicative of C trade‐offs.