scholarly journals Decomposition disentangled: a test of the multiple mechanisms by which nitrogen enrichment alters litter decomposition

2019 ◽  
Author(s):  
Noémie A. Pichon ◽  
Seraina Cappelli ◽  
Santiago Soliveres ◽  
Norbert Hölzel ◽  
Valentin H. Klaus ◽  
...  

SummaryNitrogen (N) enrichment has direct effects on ecosystem functioning by altering soil abiotic conditions and indirect effects by reducing plant diversity and shifting plant functional composition from dominance by slow to fast growing species. Litter decomposition is a key ecosystem function and is affected by N enrichment either by a change in litter quality (the recalcitrance of the plant material) or through a change in soil quality (the abiotic and biotic components of the soil that affect decomposition). The relative importance of soil and litter quality and how the direct and effects of N alter them remains poorly known.We designed a large grassland field experiment manipulating N enrichment, plant species richness and functional composition in a full factorial design. We used three complementary litter bag experiments and a novel structural equation modelling approach to quantify the relative effects of the treatments on litter and soil quality and their importance for total decomposition.Our results indicate that total decomposition was mostly driven by changes in litter quality rather than soil quality. Litter quality was affected by the nutrient contents (N and calcium) and structural components of the litter (leaf dry matter content, fibres). N enrichment increased litter decomposition mostly indirectly through a shift in functional composition toward faster growing plant species producing higher quality litter. N enrichment also had effects on soil, by directly and indirectly affected vegetation cover, but this had relatively few consequences for the total decomposition rate.Synthesis. Our approach provides a mechanistic tool to test the drivers of litter decomposition across different ecosystems. Our results show that functional composition is more important than richness or soil quality in determining litter decomposition and that N enrichment effects mainly occur via above- rather than belowground processes. This highlights the importance of considering shifts in plant species composition when assessing the effects of N enrichment on decomposition.

Limnology ◽  
2021 ◽  
Author(s):  
Viviane Caetano Firmino ◽  
Leandro Schlemmer Brasil ◽  
Renato Tavares Martins ◽  
Raphael Ligeiro ◽  
Alan Tonin ◽  
...  

2016 ◽  
Vol 135 (5) ◽  
pp. 849-856 ◽  
Author(s):  
Michiru Kasahara ◽  
Saori Fujii ◽  
Toko Tanikawa ◽  
Akira S. Mori

2017 ◽  
Vol 216 (3) ◽  
pp. 653-669 ◽  
Author(s):  
Johannes H. C. Cornelissen ◽  
Saskia Grootemaat ◽  
Lieneke M. Verheijen ◽  
William K. Cornwell ◽  
Peter M. van Bodegom ◽  
...  

2013 ◽  
Vol 16 (8) ◽  
pp. 1045-1053 ◽  
Author(s):  
Pablo García-Palacios ◽  
Fernando T. Maestre ◽  
Jens Kattge ◽  
Diana H. Wall

Plants ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2411
Author(s):  
Hamada E. Ali ◽  
Solveig Franziska Bucher

Land-use changes have huge impacts on natural vegetation, especially megaprojects, as the vegetation layer is destroyed in the course of construction works affecting the plant community composition and functionality. This large-scale disturbance might be a gateway for the establishment of invasive plant species, which can outcompete the natural flora. In contrast, species occurring in the area before the construction are not able to re-establish. In this study, we analyzed the impact of a pipeline construction on a wetland nature reserve located in northern Egypt. Therefore, we analyzed the plant species occurrence and abundance and measured each plant species’ traits before the construction in 2017 as well as on multiple occasions up to 2 years after the construction had finished on altogether five sampling events. We found that the construction activity led to the establishment of an invasive species which previously did not occur in the area, namely, Imperata cylindrica, whereas five species (Ipomoea carnea, Pluchea dioscoridis, Polygonum equisetiforme, Tamarix nilotica, and Typha domingensis) could not re-establish after the disturbance. The functionality of ecosystems assessed via the analysis of plant functional traits (plant height, specific leaf area, and leaf dry matter content) changed within species over all sampling events and within the community showing a tendency to approximate pre-construction values. Functional dispersion and Rao’s quadratic diversity were higher after the megaproject than before. These findings are important to capture possible re-establishment and recovery of natural vegetation after construction and raise awareness to the impact of megaprojects, especially in areas which are high priority for conservation.


2021 ◽  
Vol 9 ◽  
Author(s):  
Iqra Naeem ◽  
Talal Asif ◽  
Xuefeng Wu ◽  
Nazim Hassan ◽  
Liu Yiming ◽  
...  

Litter decomposition is a fundamental path for nutrient cycling in a natural ecosystem. However, it remains unclear how species diversity, including richness and evenness, affects the decomposition dynamics in the context of grassland degradation. Using a litter bag technique, we investigated the litter-mixing effects of two coexisting dominant species (Leymus chinensis Lc and Phragmites australis Pa), as monocultures and mixtures with evenness (Lc:Pa) from M1 (30:70%), M2 (50:50%), and M3 (70:30%), on decomposition processes over time (60 and 365 days). The litter bags were placed on the soil surface along a degradation gradient [near pristine (NP), lightly degraded (LD), and highly degraded (HD)]. We found that 1) mass loss in mixture compositions was significantly and positively correlated with initial nitrogen (N) and cellulose contents; 2) litter mixing (richness and evenness) influenced decomposition dynamics individually and in interaction with the incubation days and the degradation gradients; 3) in a general linear model (GLM), nonadditive antagonistic effects were more prominent than additive or neutral effects in final litter and nutrients except for carbon (C); and 4) in nutrients (C, N, lignin) and C/N ratio, additive effects shifted to nonadditive with incubation time. We speculated that the occurrence of nonadditive positive or negative effects varied with litter and nutrients mass remaining in each degraded gradient under the mechanism of initial litter quality of monoculture species, soil properties of experimental sites, and incubation time. Our study has important implications for grassland improvement and protection by considering species biodiversity richness, as well as species evenness.


2020 ◽  
Author(s):  
Noémie A. Pichon ◽  
Seraina L. Cappelli ◽  
Santiago Soliveres ◽  
Tosca Mannall ◽  
Thu Zar Nwe ◽  
...  

SummaryThe ability of an ecosystem to deliver multiple functions at high levels (multifunctionality) typically increases with biodiversity but there is substantial variation in the strength and direction of biodiversity effects, suggesting context-dependency. However, the drivers of this context dependency have not been identified and understood in comparative meta-analyses or experimental studies. To determine how different factors modulate the effect of diversity on multifunctionality, we conducted a large grassland experiment with 216 communities, crossing a manipulation of plant species richness (1-20 species) with manipulations of resource availability (nitrogen enrichment), plant functional composition (gradient in mean specific leaf area [SLA] to manipulate abundances of fast vs. slow species), plant functional diversity (variance in SLA) and enemy abundance (fungal pathogen removal). We measured ten functions, above and belowground, related to productivity, nutrient cycling and energy transfer between trophic levels, and calculated multifunctionality. Plant species richness and functional diversity both increased multifunctionality, but their effects were context dependent. Species richness increased multifunctionality, but only when communities were assembled with fast growing (high SLA) species. This was because slow species were more redundant in their functional effects, whereas fast species tended to promote different functions. Functional diversity also increased multifunctionality but this effect was dampened by nitrogen enrichment, however, unfertilised, functionally diverse communities still delivered more functions than low diversity, fertilised communities. Our study suggests that a shift towards exploitative communities will not only alter ecosystem functioning but also the strength of biodiversity-functioning relationships, which highlights the potentially complex effects of global change on multifunctionality.


2021 ◽  
Author(s):  
Haijing Hu ◽  
Rumeng Ye ◽  
Lu Pang ◽  
Han Jiang ◽  
Kai Tian ◽  
...  

Abstract Background and aims: Endophytic microorganisms exist commonly in plants and are recognized to increase plant growth especially under adverse physical environmental conditions. We here demonstrate that endophytic bacteria (EB) Bacillus cereus can accelerate the decomposition of plant litter and enhance nutrient availability for plant growth.Methods: We first obtained plant litter with and without EB inoculation using a model plant Arabidopsis thaliana in a microcosmic experiment, then conducted a litter decomposition experiment to investigated the effect of EB on litter decay rate, phosphorus availability, and on soil microbial community structure. We further evaluated wheat (Triticum aestivum) biomass growth using soils treated with and without EB.Results: Inoculation of EB significantly increased the mass loss of Arabidopsis litter in the middle stage of decomposition, elevated the activity of alkaline phosphatase in the early stage of decomposition, and increased soil available P at the end of decomposition. Analyses of Illumina MiSeq sequencing and structural equation models also indicated that EB inoculation had pronounced impact on the bacterial abundance and diversity in soil. Finally, the growth of the wheat was significantly promoted in the litter with EB decomposition system. Conclusion: EB mediated host after-life effect likely through accelerating the release of nutrients such as P from decomposing plant litter and regulating the structure of soil microorganisms, promoting the sustainability of nutrient utilization efficiency in a terrestrial ecosystem.


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