Data from: Ecosystem nitrogen retention is regulated by plant community trait interactions with nutrient status in an alpine meadow

1.Biotic nitrogen (N) retention is an important ecosystem function in the
context of ongoing land use intensification, N deposition and global
warming. However, a paucity of experimental evidence limits understanding
of how different plant community components influence N retention in
terrestrial ecosystems. 2.In this investigation we conducted a 15N
labelling experiment to test how plant community properties, including
plant species richness/diversity, dominance and functional traits,
influence plant N uptake and retention under different nutrient
availabilities. A three-year experiment examined the effects of adding N
(10 g N m−2 year−1) and phosphorus (P) (5 g P m−2 year−1) to an alpine
meadow on the Qinghai-Tibetan Plateau. 3.Results show that 15N retention
increased with the addition of N and P; the addition of P produced the
largest increase of 15N retention in plant and soil N pools. Changes in
soil nutrient conditions also facilitated different plant community
controls on ecosystem N retention. Ecosystem 15N retention was influenced
by species richness and root biomass in the control plots; whereas the N
addition treatment showed an important effect of community-weighted means
(CWM) of specific leaf area (SLA), and plots with additional P recorded
lower CWM of root nitrogen content (root N) and larger CWM root:shoot
ratios (R/S) as important determinants. 4.Synthesis. Ecosystem N retention
was influenced by conservative and exploitative plant species and/or their
traits under N deficient and abundant conditions, respectively, whereas
species richness and community plant biomass were most influential under
control conditions. The discovery of an interaction between plant
community traits and nutrient biogeochemistry as a mechanism for ecosystem
N retention offers a means to predict how vegetation in alpine meadow
ecosystems will respond to expected global change.