pH and ammonium concentration are dominant predictors of the abundance and community composition of comammox bacteria in long-term fertilized Mollisol

2021 ◽  
Vol 168 ◽  
pp. 104139
Author(s):  
Ping Sun ◽  
Shuxiang Zhang ◽  
Qihua Wu ◽  
Ping Zhu ◽  
Yunze Ruan ◽  
...  
Keyword(s):  
Community Composition ◽  
Ammonium Concentration

scholarly journals Abundance and community composition of methanotrophs in a Chinese paddy soil under long-term fertilization practices

2008 ◽  
Vol 8 (6) ◽  
pp. 406-414 ◽  
Author(s):  
Yong Zheng ◽  
Li-Mei Zhang ◽  
Yuan-Ming Zheng ◽  
Hongjie Di ◽  
Ji-Zheng He
Keyword(s):  
Community Composition ◽  
Paddy Soil

Grazing intensity rather than host plant’s palatability shape the community of arbuscular mycorrhizal fungi in a steppe grassland

2021 ◽  
Author(s):  
Maede Faghihinia ◽  
Yi Zou ◽  
Yongfei Bai ◽  
Martin Dudáš ◽  
Rob Marrs ◽  
...  
Keyword(s):  
Arbuscular Mycorrhizal Fungi ◽  
Community Composition ◽  
Mycorrhizal Fungi ◽  
Rhizosphere Soil ◽  
Grazing Intensity ◽  
Arbuscular Mycorrhizal ◽  
Grass Species ◽  
Α Diversity ◽  
Steppe Grassland

Abstract Arbuscular mycorrhizal fungi (AMF) are the predominant type of mycorrhizal fungi in roots and rhizosphere soil of grass species worldwide. Grasslands are currently experiencing increasing grazing pressure, but it is not yet clear how grazing intensity and host plant grazing preference by large herbivores interact with soil- and root-associated AMF communities. Here, we tested whether the diversity and community composition of AMF in the roots and rhizosphere soil of two dominant perennial grasses grazed differently by livestock change in response to grazing intensity. We conducted a study in a long-term field experiment in which seven levels of field-manipulated grazing intensities were maintained for 13 years in a typical steppe grassland in northern China. We extracted DNA from the roots and rhizosphere soil of two dominant grasses, Leymus chinense (Trin.) Tzvel. and Stipa grandis P. Smirn, with contrasting grazing preference by sheep. AMF DNA from root and soil samples were then subjected to molecular analysis. Our results showed that AMF α-diversity (richness) at the virtual taxa (VT) level varied as a function of grazing intensity. Different VTs showed completely different responses along the gradient, one increasing, one decreasing and others showing no response. Glomeraceae was the most abundant AMF family along the grazing gradient, which fits well with the theory of disturbance tolerance of this group. In addition, sheep grazing preference for host plants did not explain a considerable variation in AMF α-diversity. However, the two grass species exhibited different community composition in their roots and rhizosphere soils. Roots exhibited a lower α-diversity and higher β-diversity within the AMF community than soils. Overall, our results suggest that long-term grazing intensity might have changed the abundance of functionally-diverse AMF taxa in favor of those with disturbance-tolerant traits. We suggest our results would be useful in informing the choice of mycorrhizal fungi indicator variables when assessing the impacts of grassland management choices on grassland ecosystem functioning.

scholarly journals Experimental reef communities persist under future ocean acidification and warming

2021 ◽  
Author(s):  
Christopher Jury ◽  
Keisha Bahr ◽  
Evan Barba ◽  
Russell Brainard ◽  
Annick Cros ◽  
...  
Keyword(s):  
Experimental Study ◽  
Species Richness ◽  
Coral Reef ◽  
Coral Reefs ◽  
Ocean Acidification ◽  
Community Composition ◽  
Functional State ◽  
Reef Communities ◽  
Paris Climate Agreement

Abstract Coral reefs are among the most sensitive ecosystems affected by ocean acidification and warming, and are predicted to shift from net accreting calcifier-dominated systems to net eroding algal-dominated systems over the coming decades. Here we present a long-term experimental study examining the responses of entire mesocosm coral reef communities to acidification (-0.2 pH units), warming (+ 2°C), and combined future ocean (-0.2 pH, + 2°C) treatments. We show that under future ocean conditions, net calcification rates declined yet remained positive, corals showed reduced abundance yet were not extirpated, and community composition shifted while species richness was maintained. Our results suggest that under Paris Climate Agreement targets, coral reefs could persist in an altered functional state rather than collapse.

scholarly journals Responses of fungal community composition to long-term chemical and organic fertilization strategies in Chinese Mollisols

2018 ◽  
Vol 7 (5) ◽  
pp. e00597 ◽  
Author(s):  
Mingchao Ma ◽  
Xin Jiang ◽  
Qingfeng Wang ◽  
Marc Ongena ◽  
Dan Wei ◽  
...  
Keyword(s):  
Community Composition ◽  
Fungal Community ◽  
Organic Fertilization ◽  
Fungal Community Composition

scholarly journals Differential arthropod responses to warming are altering the structure of Arctic communities

2018 ◽  
Vol 5 (4) ◽  
pp. 171503 ◽  
Author(s):  
Amanda M. Koltz ◽  
Niels M. Schmidt ◽  
Toke T. Høye
Keyword(s):  
Community Composition ◽  
Primary Productivity ◽  
Species Interactions ◽  
Ecosystem Processes ◽  
The Arctic ◽  
Individual Species ◽  
Freeze Thaw ◽  
Compositional Changes ◽  
Arctic Communities

The Arctic is experiencing some of the fastest rates of warming on the planet. Although many studies have documented responses to such warming by individual species, the idiosyncratic nature of these findings has prevented us from extrapolating them to community-level predictions. Here, we leverage the availability of a long-term dataset from Zackenberg, Greenland (593 700 specimens collected between 1996 and 2014), to investigate how climate parameters influence the abundance of different arthropod groups and overall community composition. We find that variation in mean seasonal temperatures, winter duration and winter freeze–thaw events is correlated with taxon-specific and habitat-dependent changes in arthropod abundances. In addition, we find that arthropod communities have exhibited compositional changes consistent with the expected effects of recent shifts towards warmer active seasons and fewer freeze–thaw events in NE Greenland. Changes in community composition are up to five times more extreme in drier than wet habitats, with herbivores and parasitoids generally increasing in abundance, while the opposite is true for surface detritivores. These results suggest that species interactions and food web dynamics are changing in the Arctic, with potential implications for key ecosystem processes such as decomposition, nutrient cycling and primary productivity.

Understanding the Long-Term Weed Community Dynamics in Organic and Conventional Crop Rotations Using the Principal Response Curve Method

Weed Science ◽  
2019 ◽  
Vol 67 (2) ◽  
pp. 195-204 ◽  
Author(s):  
Dilshan Benaragama ◽  
Julia L. Leeson ◽  
Steve J. Shirtliffe
Keyword(s):  
Community Composition ◽  
Community Dynamics ◽  
Cropping Systems ◽  
High Input ◽  
Organic Systems ◽  
No Till ◽  
Principal Response Curve ◽  
Predominant Factor ◽  
Conventional Systems

AbstractWeeds have acquired evolutionary adaptations to the diverse crop and weed management strategies used in cropping systems. Therefore, changes in crop production practices such as conventional to organic systems, tillage-based to no-till systems, and diversity in crop rotations can result in differences in weed community composition that have management implications. A study was carried out to understand the weed community dynamics in a long-term alternative cropping systems study at Scott, SK, Canada. Long-term (18-yr) weed community composition data in wheat (Triticum aestivumL.) in ORG (organic), RED (reduced-input, no-till), and HIGH (high-input, conventional tillage) systems with three levels of crop rotation diversity, LOW (low diversity), DAG (diversified annual grains), and DAP (diversified annuals and perennials), were used to study the effect of different cropping systems and the effect of environment (random temporal effects) on residual weed community composition using the principal response curve (PRC) technique. The interaction between cropping systems and year-to-year random environmental changes was found to be the predominant factor causing fluctuations in weed community composition. Furthermore, the single most predominant factor influencing the weed composition was year-to-year random changes. Organic systems clearly differed from the two conventional systems in most years and had more diverse weed communities compared with the two conventional systems. The two conventional systems exhibited similar weed composition in most years. In this study, the use of the PRC method allowed capture of the real temporal dynamics reflected in the cropping systems by time interaction. This study further concludes that moving from a tillage-based, high-input conventional system to a no-till, reduced-input system did not cause significant changes in the weed community composition throughout the time period, but diversity in organic systems was high, probably due to increased occurrence of some difficult to control species.

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