10.5061/DRYAD.02V6WWQ1T
Cai, Jiangping
0000-0001-7808-3238
Institute of Applied Ecology
Weiner, Jacob
University of Copenhagen
Luo, Wentao
Institute of Applied Ecology
Feng, Xue
Institute of Applied Ecology
Yang, Guojiao
Institute of Applied Ecology
Lu, Jiayu
Institute of Applied Ecology
Lü, Xiao-tao
Institute of Applied Ecology
Li, Mai-He
0000-0002-7029-2841
Swiss Federal Institute for Forest, Snow and Landscape Research
Jiang, Yong
Institute of Applied Ecology
Han, Xingguo
Institute of Botany
Functional structure mediates the responses of productivity to addition of
three nitrogen compounds in a meadow steppe
Dryad
dataset
2020
FOS: Natural sciences
National Natural Science Foundation of China
https://ror.org/01h0zpd94
32271655, 32001386
National Natural Science Foundation of China
https://ror.org/01h0zpd94
C2022201042
Major Special Science and Technology Project of Liaoning Province*
2020JH1/10300006
National Natural Science Foundation of China
https://ror.org/01h0zpd94
2020-BS-023
2020-10-09T00:00:00Z
2020-10-09T00:00:00Z
en
59611 bytes
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CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Atmospheric nitrogen (N) deposition is altering grassland productivity and
community structure worldwide. Deposited N comes in different forms, which
can have different consequences for productivity due to differences in
their fertilization and acidification effects. We hypothesize that these
effects may be mediated by changes in plant functional traits. We
investigated the responses of aboveground primary productivity and
community functional composition to addition of three nitrogen compounds
(NH4NO3, [NH4]2SO4, and CO[NH2]2) at the rates of 0, 5, 10, 20 g N m-2
yr-1. We used structural equation modeling (SEM) to evaluate how
functional structure influences the responses of productivity to the three
N compounds. Nitrogen addition increased community-level leaf chlorophyll
content but decreased leaf dry matter content and phosphorus
concentration. These changes were mainly due to intra-specific variation.
Functional dispersion of traits was reduced by N addition through changes
in species composition. SEM revealed that fertilization effects were more
important than soil acidification for the responses of productivity to
CO(NH2)2 addition, which enhanced productivity by decreasing functional
trait dispersion. In contrast, the effects of (NH4)2SO4 and NH4NO3 were
primarily due to soil acidification, influencing productivity via
community-weighted means of functional traits. Our results suggest that N
forms with different fertilizing and acidifying effects influence
productivity via different functional traits pathways. Our study also
emphasizes the need for in situ experiments with the relevant N compounds
to accurately understand and predict the ecological effects of atmospheric
N deposition on ecosystems.
We assessed the total aboveground biomass (g/m2) and the relative
aboveground biomass of each species in a 1 m × 1 m randomly established
quadrat in each plot in August 2017. All aboveground parts of vascular
plants were harvested and sorted into species and then dried at 65℃ for
48h before weighing for dry biomass. After recording all species occurred
in the studied quadrat of each plot, we collected fresh leaves for all
those species within each plot, to measure their specific leaf area (SLA,
the ratio of leaf area to leaf dry mass, cm2/g), leaf dry matter content
(LDMC, the ratio of leaf dry mass to water saturated fresh mass, mg/g),
leaf chlorophyll content (Chls, mg/g), and leaf phosphorus concentration
based on mass (LPC, mg/kg) of all the emerging species. In each plot,
topsoil samples (0–10 cm) were taken from five random soil cores after
removing litter and mixed to form one composite sample. Soil pH was
determined in a 1:2.5 soil-to-water suspension with a pH electrode (S210
SevenCompact™, Mettler, Gießen, Germany).
Community weighted mean (CWM) for each functional trait was weighted by
the relative biomass of each species (Garnier et al., 2004). Community
functional dispersion (FDis) was calculated based on the four functional
traits and every single trait. FDis was calculated as the average distance
of each individual species to the centroid of all species in the community
trait space, and FDis of multi-trait is multi-dimensional index based on
multi-trait space.