Effects of elevated CO
, increased nitrogen deposition, and plant
diversity on aboveground litter and root decomposition
M. H. K
Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000 China
School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska 62588 USA
Citation: Zuo, X., and J. M. H. Knops. 2018. Effects of elevated CO
, increased nitrogen deposition, and plant diversity
on aboveground litter and root decomposition. Ecosphere 9(2):e02111. 10.1002/ecs2.2111
Global change-induced litter decomposition strongly affects the carbon (C) and nitrogen (N)
dynamics in grassland ecosystems. However, few studies show the interactive effects of global change fac-
tors on litter and root decomposition. We conducted a four-year grassland ﬁeld experiment to examine the
quality and decomposition of litter and root in a three-factorial experiment with elevated CO
, increased N
deposition, and plant species richness. We found that elevated CO
decreased the litter N content and root
lignin content. N addition increased the root N content and decreased the litter lignin content. Increasing
plant richness decreased the N and lignin contents in litter and root. In contrast to the quality changes, ele-
had no effect on decomposition of litter and root. N addition increased the C loss of the litter by
4.8%, but did not affect C and N loss in root. Increasing plant richness affected the C and N loss in litter
and root. ANCOVAs showed that tissue quality and root biomass affected the C and N loss in litter and
root, and soil C and N affected the N loss of litter and root. However, changes in tissue quality, biomass,
and soil as covariates did not signiﬁcantly change the effects of CO
, N, and plant richness on decomposi-
tion. The structural equation model showed that elevated CO
indirectly decreased litter N loss and
increased root N loss, while N addition indirectly increased the C and N loss in litter and root, via their
effects on tissue quality. Increasing plant richness increased litter C and N loss, but indirectly decreased
root C and N loss. N deposition can accelerate litter and root decomposition, thus modifying the limitation
of elevated CO
on soil N availability. Biodiversity loss greatly alters litter and root decomposition, poten-
tially driving any changes in C and N cycling. Our study clearly demonstrates a relative certainty of a pre-
dicted increase in the C loss and N release in litter and root decomposition with increased N deposition,
whereas the effects of elevated CO
and plant diversity changes on decomposition strongly differ between
litter and root in grassland ecosystems.
Key words: biodiversity; decomposition rate; direct or indirect effect; global change; nitrogen addition; tissue quality.
Received 6 January 2018; accepted 10 January 2018. Corresponding Editor: Debra P. C. Peters.
Copyright: © 2018 Zuo and Knops. This is an open access article under the terms of the Creative Commons Attribution
License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Litter decomposition may accelerate or deceler-
ate global climate changes, because changes in lit-
ter quantity and quality can change both the
cycling rates and the pools of carbon (C) and
nutrients within an ecosystem (Dijkstra et al.
2004, Sierra et al. 2011, van Groenigen et al. 2014).
Litter decomposition in terrestrial ecosystems is
mainly driven by the litter chemical components
and climatic factors (Co
uteaux et al. 1995, Garcia-
Palacios et al. 2013a, 2017). Global climate
changes can strongly affect litter decomposition
due to the changes in physical decomposition
environment induced by temperature or precipi-
tation and the indirect roles through their effects
on productivity and litter quality (Zhang et al.
2008, Boyero et al. 2011). Global changes, such as