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Evidence from the real world: 15 N natural abundances reveal enhanced nitrogen use at high plant diversity in Central European grasslands
Author(s) -
Kleinebecker Till,
Hölzel Norbert,
Prati Daniel,
Schmitt Barbara,
Fischer Markus,
Klaus Valentin H.
Publication year - 2014
Publication title -
journal of ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.452
H-Index - 181
eISSN - 1365-2745
pISSN - 0022-0477
DOI - 10.1111/1365-2745.12202
Subject(s) - biodiversity , species richness , biomass (ecology) , environmental science , plant community , ecology , abundance (ecology) , ecosystem , abiotic component , species diversity , alpha diversity , nitrogen cycle , biology , nitrogen , chemistry , organic chemistry
Summary Complementarity that leads to more efficient resource use is presumed to be a key mechanism explaining positive biodiversity–productivity relationships but has been described solely for experimental set‐ups with controlled environmental settings or for very short gradients of abiotic conditions, land‐use intensity and biodiversity. Therefore, we analysed plant diversity effects on nitrogen dynamics across a broad range of Central European grasslands. The 15 N natural abundance in soil and plant biomass reflects the net effect of processes affecting ecosystem N dynamics. This includes the mechanism of complementary resource utilization that causes a decrease in the 15 N isotopic signal. We measured plant species richness, natural abundance of 15 N in soil and plants, above‐ground biomass of the community and three single species (an herb, grass and legume) and a variety of additional environmental variables in 150 grassland plots in three regions of Germany. To explore the drivers of the nitrogen dynamics, we performed several analyses of covariance treating the 15 N isotopic signals as a function of plant diversity and a large set of covariates. Increasing plant diversity was consistently linked to decreased δ 15 N isotopic signals in soil, above‐ground community biomass and the three single species. Even after accounting for multiple covariates, plant diversity remained the strongest predictor of δ 15 N isotopic signals suggesting that higher plant diversity leads to a more closed nitrogen cycle due to more efficient nitrogen use. Factors linked to increased δ 15 N values included the amount of nitrogen taken up, soil moisture and land‐use intensity (particularly fertilization), all indicators of the openness of the nitrogen cycle due to enhanced N‐turnover and subsequent losses. Study region was significantly related to the δ 15 N isotopic signals indicating that regional peculiarities such as former intensive land use could strongly affect nitrogen dynamics. Synthesis . Our results provide strong evidence that the mechanism of complementary resource utilization operates in real‐world grasslands where multiple external factors affect nitrogen dynamics. Although single species may differ in effect size, actively increasing total plant diversity in grasslands could be an option to more effectively use nitrogen resources and to reduce the negative environmental impacts of nitrogen losses.