Long‐term warming effects on the microbiome and nifH gene abundance of a common moss species in sub‐Arctic tundra

2021 ◽  
Author(s):  
Ingeborg J. Klarenberg ◽  
Christoph Keuschnig ◽  
Ana J. Russi Colmenares ◽  
Denis Warshan ◽  
Anne D. Jungblut ◽  
...  
Keyword(s):  
Nifh Gene ◽  
Arctic Tundra ◽  
Moss Species ◽  
Gene Abundance

scholarly journals The Multiscale Monitoring of Peatland Ecosystem Carbon Cycling in the Middle Taiga Zone of Western Siberia: The Mukhrino Bog Case Study

Land ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 824
Author(s):  
Egor Dyukarev ◽  
Evgeny Zarov ◽  
Pavel Alekseychik ◽  
Jelmer Nijp ◽  
Nina Filippova ◽  
...  
Keyword(s):  
Carbon Cycling ◽  
Western Siberia ◽  
Carbon Accumulation ◽  
Middle Taiga ◽  
Taiga Zone ◽  
Field Station ◽  
Moss Species ◽  
Chamber Method ◽  
The Impact

The peatlands of the West Siberian Lowlands, comprising the largest pristine peatland area of the world, have not previously been covered by continuous measurement and monitoring programs. The response of peatlands to climate change occurs over several decades. This paper summarizes the results of peatland carbon balance studies collected over ten years at the Mukhrino field station (Mukhrino FS, MFS) operating in the Middle Taiga Zone of Western Siberia. A multiscale approach was applied for the investigations of peatland carbon cycling. Carbon dioxide fluxes at the local scale studied using the chamber method showed net accumulation with rates from 110, to 57.8 gC m−2 at the Sphagnum hollow site. Net CO2 fluxes at the pine-dwarf shrubs-Sphagnum ridge varied from negative (−32.1 gC m−2 in 2019) to positive (13.4 gC m−2 in 2017). The cumulative May-August net ecosystem exchange (NEE) from eddy-covariance (EC) measurements at the ecosystem scale was −202 gC m−2 in 2015, due to the impact of photosynthesis of pine trees which was not registered by the chamber method. The net annual accumulation of carbon in the live part of mosses was estimated at 24–190 gC m−2 depending on the Sphagnum moss species. Long-term carbon accumulation rates obtained by radiocarbon analysis ranged from 28.5 to 57.2 gC m−2 yr−1, with local extremes of up to 176.2 gC m−2 yr−1. The obtained estimates of various carbon fluxes using EC and chamber methods, the accounting for Sphagnum growth and decomposition, and long-term peat accumulation provided information about the functioning of the peatland ecosystems at different spatial and temporal scales. Multiscale carbon flux monitoring reveals useful new information for forecasting the response of northern peatland carbon cycles to climatic changes.

Long-term experimentally deepened snow decreases growing-season respiration in a low- and high-arctic tundra ecosystem

2016 ◽  
Vol 121 (5) ◽  
pp. 1236-1248 ◽  
Author(s):  
Philipp R. Semenchuk ◽  
Casper T. Christiansen ◽  
Paul Grogan ◽  
Bo Elberling ◽  
Elisabeth J. Cooper
Keyword(s):  
Growing Season ◽  
Arctic Tundra ◽  
High Arctic ◽  
Tundra Ecosystem

scholarly journals Dry Heath Arctic Tundra Responses to Long-term Nutrient and Light Manipulation

2002 ◽  
Vol 34 (2) ◽  
pp. 211-218 ◽  
Author(s):  
L. Gough ◽  
P. A. Wookey ◽  
G. R. Shaver
Keyword(s):  
Arctic Tundra ◽  
Light Manipulation

Long-term nitrogen fertilization shaped the nifH, nirK and nosZ gene community patterns in red paddy soil in south China。

2020 ◽  
Author(s):  
Cunzhi Zhang ◽  
Kaixun Cao ◽  
Yue Li ◽  
Juan Zhao ◽  
Wentao Peng ◽  
...  
Keyword(s):  
Paddy Soil ◽  
Gene Diversity ◽  
Nifh Gene ◽  
Community Patterns ◽  
Factors Affecting ◽  
Nitrogen Fixers ◽  
Potential Link ◽  
Chemical Factors ◽  
Red Paddy Soil

To understand the diversities of diazotrophs and denitrifiers in red paddy soil under long-term fertilization conditions, nifH, nirK and nosZ libraries were constructed based on the PCR-RFLP method. nirK gene diversity proved to be lower than that of nosZ and nifH, and nirK and nosZ genes were more sensitive to different fertilization treatments than those with the nifH gene. Diverse microbes including the α-, β-, γ- and δ- subclasses of the Proteobacteria dominated the three libraries. Long-term addition of urea with straw-mulching and azophoska increased the abundance of non-symbiotic diazotrophs, which indicated that non-symbiotic diazotrophs were responsible for the majority of the nitrogen-fixing ability in paddy soil. In addition, a potential link between nifH and nosZ was found due to the existence of nitrogen fixers, such as Bradyrhizobium and Ralstonia in the nosZ library. The main chemical factors affecting the three genes were identified, pH was the most important factor of nifH community, and nirK genes were more affected by pH and organic matter, available potassium and carbon to nitrogen ratio significantly influenced the community structure of the nosZ genes.

Nitrogen fixation beyond leguminous plants: characterising overlooked plant-bacteria associations in the light of climate change

2020 ◽  
Author(s):  
Kathrin Rousk
Keyword(s):  
Climate Change ◽  
Nitrogen Fixation ◽  
Community Composition ◽  
Abiotic Factors ◽  
Arctic Tundra ◽  
The Arctic ◽  
Mean Annual Precipitation ◽  
Precipitation Gradient ◽  
Cyanobacterial Community ◽  
Moss Species

<p>Nitrogen (N<sub>2</sub>) fixation performed by moss-associated cyanobacteria is one of the main sources of new N in pristine, high latitude ecosystems like boreal forests and arctic tundra. Here, mosses and associated cyanobacteria can contribute more than 50% to total ecosystem N input. However, N<sub>2</sub> fixation in mosses is strongly influenced by abiotic factors, in particular moisture and temperature. Hence, climate change will significantly affect this key ecosystem process in pristine ecosystems. Here, I will present a synthesis of several field and laboratory assessments of moss-associated N<sub>2</sub> fixation in response to climate change by manipulating moisture and temperature in subarctic and arctic tundra.</p><p>Both in a long-term climate warming experiment in the arctic, and along a continental climate gradient, spanning arctic, subarctic and temperate ecosystems, increased temperatures (up to 30 °C) lead to either no effect or decreased N<sub>2</sub> fixation rates in different moss species. Yet, N<sub>2</sub> fixation rates were strongly dependent on moss-moisture, which seems to be a more important driver of N<sub>2</sub> fixation in mosses than temperature.</p><p>In another set of studies, two dominant moss species (Hylocomium splendens, Pleurozium schreberi) were collected from a steep precipitation gradient (400-1200 mm mean annual precipitation, MAP) in the Subarctic close to Abisko, Northern Sweden, and were incubated at different moisture and temperature levels in the laboratory. Nitrogen fixation, cyanobacterial abundance (via qPCR) and cyanobacterial community composition (via sequencing) on the mosses were assessed. Moisture and temperature interacted strongly to control moss-associated N<sub>2</sub> fixation rates, and the highest activity was found at the wet end of the precipitation gradient. Although cyanobacterial abundance was higher in one of the investigated mosses (H. splendens), translating into higher N<sub>2</sub> fixation rates, cyanobacterial community composition did not differ between the two moss species. Nostoc was the most common cyanobacterial genera on both mosses, and hardly any methanotrophic N<sub>2</sub> fixing bacteria were found on the mosses along the precipitation gradient. Increased temperatures lead to increased abundances of certain cyanobacterial genera (Cylindrospermum and Nostoc), while others declined in response to warming. Hence, cyanobacterial communities colonizing mosses will be dominated by a few cyanobacteria species in a warmer climate, and temperature and moisture interact strongly to affect their activity. Thus, these two major climate change factors should be considered in unison when estimating climate change effects on key ecosystem processes such as N<sub>2</sub> fixation. Further, host identity determines cyanobacterial abundance, and thereby, N<sub>2</sub> fixation rates.</p><p> </p><p> </p><p> </p>

scholarly journals Microbial community composition and abundance after millennia of submarine permafrost warming

2019 ◽  
Author(s):  
Julia Mitzscherling ◽  
Fabian Horn ◽  
Maria Winterfeld ◽  
Linda Mahler ◽  
Jens Kallmeyer ◽  
...  
Keyword(s):  
Microbial Community ◽  
Community Composition ◽  
Pore Water ◽  
Negative Correlation ◽  
Microbial Community Composition ◽  
Microbial Abundance ◽  
Bacterial Gene ◽  
Gene Abundance ◽  
Permafrost Warming

Abstract. Warming of the Arctic led to an increase of permafrost temperatures by about 0.3 °C during the last decade. Permafrost warming is associated with increasing sediment water content, permeability and diffusivity and could on the long-term alter microbial community composition and abundance even before permafrost thaws. We studied the long-term effect (up to 2500 years) of submarine permafrost warming on microbial communities along an onshore-offshore transect on the Siberian Arctic Shelf displaying a natural temperature gradient of more than 10 °C. We analysed the in-situ development of bacterial abundance and community composition through total cell counts (TCC), quantitative PCR of bacterial gene abundance and amplicon sequencing, and correlated the microbial community data with temperature, pore water chemistry and sediment physicochemical parameters. On time-scales of centuries, permafrost warming coincided with an overall decreasing microbial abundance while millennia after warming microbial abundance was similar to cold onshore permafrost and DOC content was least. Based on correlation analysis TCC unlike bacterial gene abundance showed a significant rank-based negative correlation with increasing temperature while both TCC and bacterial gene copy numbers showed a negative correlation with salinity. Bacterial community composition correlated only weakly with temperature but strongly with pore-water stable isotope signatures and depth, while it showed no correlation with salinity. Microbial community composition showed substantial spatial variation and an overall dominance of Actinobacteria, Chloroflexi, Firmicutes, Gemmatimonadetes and Proteobacteria which are amongst the microbial taxa that were found to be active in other frozen permafrost environments as well. We suggest that, millennia after permafrost warming by over 10 °C, microbial community composition and abundance show some indications for proliferation but mainly reflect the sedimentation history and paleo-environment and not a direct effect through warming.

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