Journal ArticleDOI
Tradeoffs and thresholds in the effects of nitrogen addition on biodiversity and ecosystem functioning: evidence from inner Mongolia Grasslands
Yongfei Bai,Jianguo Wu,Jianguo Wu,Christopher M. Clark,Shahid Naeem,Qingmin Pan,Jianhui Huang,Lixia Zhang,Xingguo Han +8 more
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TLDR
It is suggested that the critical threshold for N-induced species loss to mature Eurasian grasslands is below 1.75gNm � 2 yr � 1, and that changes in aboveground biomass, species richness, and plant functional group composition to both mature and degraded ecosystems saturate at N addition rates of approximately 10.5 gNm� 2 yr� 1.Abstract:
Nitrogen (N) deposition is widely considered an environmental problem that leads to biodiversity loss and reduced ecosystem resilience; but, N fertilization has also been used as a management tool for enhancing primary production and ground cover, thereby promoting the restoration of degraded lands. However, empirical evaluation of these contrasting impacts is lacking. We tested the dual effects of N enrichment on biodiversity and ecosystem functioning at different organizational levels (i.e., plant species, functional groups, and community) by adding N at 0, 1.75, 5.25, 10.5, 17.5, and 28.0gNm � 2 yr � 1 for four years in two contrasting field sites in Inner Mongolia: an undisturbed mature grassland and a nearby degraded grassland of the same type. N addition had both quantitatively and qualitatively different effects on the two communities. In the mature community, N addition led to a large reduction in species richness, accompanied by increased dominance of early successional annuals and loss of perennial grasses and forbs at all N input rates. In the degraded community, however, N addition increased the productivity and dominance of perennial rhizomatous grasses, with only a slight reduction in species richness and no significant change in annual abundance. The mature grassland was much more sensitive to N-induced changes in community structure, likely as a result of higher soil moisture accentuating limitation by N alone. Our findings suggest that the critical threshold for N-induced species loss to mature Eurasian grasslands is below 1.75gNm � 2 yr � 1 , and that changes in aboveground biomass, species richness, and plant functional group composition to both mature and degraded ecosystems saturate at N addition rates of approximately 10.5gNm � 2 yr � 1 . This work highlights the tradeoffs that exist in assessing the total impact of N deposition on ecosystem function.read more
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Journal ArticleDOI
Grazing intensity mediates effects of plant arbuscular mycorrhizal symbiosis on nitrogen and phosphorus resorption in semiarid grasslands
Journal ArticleDOI
Phosphorus availability and planting patterns regulate soil microbial effects on plant performance in a semiarid steppe
TL;DR: In this article , the effects of the whole indigenous soil microbiota on the growth and performance of Leymus chinensis and Cleistogenes squarrosa using soil sterilization with different soil phosphorus availabilities and planting patterns (monoculture and mixture).
Journal ArticleDOI
Effects of nitrogen and water addition on soil carbon, nitrogen, phosphorus, sulfur, and their stoichiometry along soil profile in a semi-arid steppe
Guoxiang Niu,Buqing Zhong,Ruzhen Wang,Yiqian Jin,Yinliu Wang,Xiaotao Lü,Yong Jiang,Jianhui Huang +7 more
TL;DR: In this article , the authors evaluated the effects of increased nitrogen (N) and water inputs on these ratios across soil depths in a semi-arid grassland of the Mongolian Plateau.
PRODUCCIÓN DE MS, COMPOSICIÓN QUÍMICA DEL SUELO Y TASA DE INFILTRACIÓN, DESPUÉS DE 25 AÑOS DE EXCLUSIÓN AL PASTOREO Y ELIMINACIÓN DE ARBUSTOS (EXCEPTO Atriplex canescens) EN UN MATORRAL PARVIFOLIO INERME EN EL NORTE DE MÉXICO
Suárez Hernández,Eliseo Bernabel +1 more
TL;DR: Determinar el efecto de 25 anos de the exclusion del pastoreo de ganado and the eliminacion of los arbustos sobre the produccion of materia seca de la vegetacion, the composicion quimica del suelo and the tasa de infiltracion en un matorral parvifolio inerme en the norte of Mexico.
Journal ArticleDOI
Soil Microbial Legacy Overrides the Responses of a Dominant Grass and Nitrogen-Cycling Functional Microbes in Grassland Soil to Nitrogen Addition
TL;DR: In this article , the authors investigated the role of soil microbial legacy (SML) in assessing the effects of N deposition on dominant plant performance and N-cycling functional genes (NCFGs) in grassland vegetation succession.
References
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Journal ArticleDOI
Human alteration of the global nitrogen cycle: sources and consequences
Peter M. Vitousek,John D. Aber,Robert W. Howarth,Gene E. Likens,Pamela A. Matson,David W. Schindler,William H. Schlesinger,David Tilman +7 more
TL;DR: In this article, a review of available scientific evidence shows that human alterations of the nitrogen cycle have approximately doubled the rate of nitrogen input into the terrestrial nitrogen cycle, with these rates still increasing; increased concentrations of the potent greenhouse gas N 2O globally, and increased concentration of other oxides of nitrogen that drive the formation of photochemical smog over large regions of Earth.
Journal ArticleDOI
Nitrogen limitation on land and in the sea: How can it occur?
TL;DR: In this paper, the authors examine both how the biogeochemistry of the nitrogen cycle could cause limitation to develop, and how nitrogen limitation could persist as a consequence of processes that prevent or reduce nitrogen fixation.
Book ChapterDOI
Nitrogen - inorganic forms.
TL;DR: In this article, Bremner et al. defined the nonexchangeable NHt as the NHt in soil that cannot be replaced by a neutral potassium salt solution (SSSA, 1987), in contrast to NHt which is extractable at room temperature with such a solution.