Premium
Nitrogen availability and colonization by mycorrhizal fungi correlate with nitrogen isotope patterns in plants
Author(s) -
Hobbie Erik A.,
Colpaert Jan V.
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.1469-8137.2003.00657.x
Subject(s) - ectomycorrhiza , biology , mycorrhiza , hypha , biomass (ecology) , isotopes of nitrogen , productivity , nitrogen , botany , ecosystem , stable isotope ratio , colonization , symbiosis , agronomy , ecology , chemistry , bacteria , genetics , physics , macroeconomics , organic chemistry , quantum mechanics , economics
Summary• Nitrogen isotope (δ 15 N) patterns in plants may provide insight into plant N dynamics. Here, two analytical models of N‐isotope cycling in plants and mycorrhizal fungi were tested, as dominant plants in many forest ecosystems obtain most of their N through intereactions with mycorrhizal fungi. • Fungi were treated either as a single well‐mixed N pool, or as two N pools (one available, plus one not available, for transfer to the host). Models were compared against complete biomass and 15N budgets from culture studies of nonmycorrhizal and ectomycorrhizalPinus sylvestris(colonized withSuillus luteusorThelephora terrestris ) grown exponentially at low and high N supply. • Fungal biomass and N increased at low N relative to high N supply, whereas needle δ 15N decreased. Needle δ15N correlated strongly and negatively with biomass of extraradical hyphae. Our data and models suggest that low plant δ15N values in low productivity and N‐limited environments result partly from high retention of15N‐enriched N by mycorrhizal fungi; this retention was driven by increased C flux to fungi under N‐limited conditions. The two‐pool model of fungal N accounted for greater variability in plant δ15 N than the one‐pool model. • Plant δ 15N patterns may indicate relative allocation of fixed C from plants to mycorrhizal fungi under some conditions. Studies are needed on whether patterns observed in culture can be applied to interpret field measurements of δ15 N.