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Foliar and soil δ 15 N values reveal increased nitrogen partitioning among species in diverse grassland communities
Author(s) -
GUBSCH MARLÉN,
ROSCHER CHRISTIANE,
GLEIXNER GERD,
HABEKOST MAIKE,
LIPOWSKY ANNETT,
SCHMID BERNHARD,
SCHULZE ERNSTDETLEF,
STEINBEISS SIBYLLE,
BUCHMANN NINA
Publication year - 2011
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2011.02287.x
Subject(s) - grassland , legume , agronomy , nitrogen , nitrogen fixation , soil water , biology , sowing , botany , chemistry , ecology , organic chemistry
Plant and soil nitrogen isotope ratios ( δ 15 N) were studied in experimental grassland plots of varying species richness. We hypothesized that partitioning of different sources of soil nitrogen among four plant functional groups (legumes, grasses, small herbs, tall herbs) should increase with diversity. Four years after sowing, all soils were depleted in 15 N in the top 5 cm whereas in non‐legume plots soils were enriched in 15 N at 5–25 cm depth. Decreasing foliar δ 15 N and Δ δ 15 N (= foliar δ 15 N − soil δ 15 N) values in legumes indicated increasing symbiotic N 2 fixation with increasing diversity. In grasses, foliar Δ δ 15 N also decreased with increasing diversity suggesting enhanced uptake of N depleted in 15 N. Foliar Δ δ 15 N values of small and tall herbs were unaffected by diversity. Foliar Δ δ 15 N values of grasses were also reduced in plots containing legumes, indicating direct use of legume‐derived N depleted in 15 N. Increased foliar N concentrations of tall and small herbs in plots containing legumes without reduced foliar δ 15 N indicated that these species obtained additional mineral soil N that was not consumed by legumes. These functional group and species specific shifts in the uptake of different N sources with increasing diversity indicate complementary resource use in diverse communities.