What drives biological nitrogen fixation in high arctic tundra: Moisture or temperature?

Rousk, Kathrin; Sørensen, Pernille Lærkedal; Michelsen, Anders

doi:10.1002/ecs2.2117

Cited by 54 publications

(57 citation statements)

References 52 publications

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“…On the contrary, we found a net positive effect of warming on soil DON. Although there are exceptions to this trend (e.g., Rousk et al 2018, Stark et al 2018, our meta-analysis suggests that warming in cold ecosystems could lead to a net accumulation of belowground N in the form of DON. Similar increases in DON with warming have been observed elsewhere (e.g., Kane et al 2014, Schaeffer et al 2013.…”

Section: Warming Leads To a Net Accumulation Of Don In Cold Ecosystemsmentioning

confidence: 58%

“…For example, in a subarctic wet heath in northern Sweden, overall growing-season N fixation by moss-associated diazotrophs was about three times larger in plots that had been warmed with dome-shaped plastic greenhouses for 10 yr than in unmanipulated plots (Sorensen and Michelsen 2011). A more recent study at the same site , and a similar experiment in the high Arctic, Greenland (Rousk et al 2018), found no effects of warming on N fixation. In the same area, 21 yr of warming had either no effect or a negative effect on N fixation in the mosses Hylocomium splendens and Aulacomnium turgidum, respectively (Sorensen et al 2012).…”

Section: No Evidence Of Warming Affecting N Fixation In a Consistent mentioning

confidence: 90%

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Faster nitrogen cycling and more fungal and root biomass in cold ecosystems under experimental warming: a meta‐analysis

Salazar

Rousk

Jónsdóttir

et al. 2019

Ecology

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esson. 2020. Faster nitrogen cycling and more fungal and root biomass in cold ecosystems under experimental warming: a meta-analysis. Ecology 101(2):Abstract. Warming can alter the biogeochemistry and ecology of soils. These alterations can be particularly large in high northern latitude ecosystems, which are experiencing the most intense warming globally. In this meta-analysis, we investigated global trends in how experimental warming is altering the biogeochemistry of the most common limiting nutrient for biological processes in cold ecosystems of high northern latitudes (>50°): nitrogen (N). For comparison, we also analyzed cold ecosystems at intermediate and high southern latitudes. In addition, we examined N-relevant genes and enzymes, and the abundance of belowground organisms. Together, our findings suggest that warming in cold ecosystems increases N mineralization rates and N 2 O emissions and does not affect N fixation, at least not in a consistent way across biomes and conditions. Changes in belowground N fluxes caused by warming lead to an accumulation of N in the forms of dissolved organic and root N. These changes seem to be more closely linked to increases in enzyme activity that target relatively labile N sources, than to changes in the abundance of N-relevant genes (e.g., amoA and nosZ). Finally, our analysis suggests that warming in cold ecosystems leads to an increase in plant roots, fungi, and (likely in an indirect way) fungivores, and does not affect the abundance of archaea, bacteria, or bacterivores. In summary, our findings highlight global trends in the ways warming is altering the biogeochemistry and ecology of soils in cold ecosystems, and provide information that can be valuable for prediction of changes and for management of such ecosystems.

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Section: Warming Leads To a Net Accumulation Of Don In Cold Ecosystemsmentioning

confidence: 58%

Section: No Evidence Of Warming Affecting N Fixation In a Consistent mentioning

confidence: 90%

Faster nitrogen cycling and more fungal and root biomass in cold ecosystems under experimental warming: a meta‐analysis

Salazar

Rousk

Jónsdóttir

et al. 2019

Ecology

Self Cite

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“…N 2 fixation rates of moss-associated diazotrophic bacteria can be expected to increase with temperature, as metabolic processes in microorganisms increase with temperature and the enzyme nitrogenase is more active at higher temperatures [30]. Temperature induced drought however, can inhibit N 2 fixation rates, especially cyanobacterial N 2 fixation [9, 24, 31–36]. Temperature effects on N 2 fixation rates might also be influenced by physiological adaptation of diazotrophic communities, or shifts to a species composition better suited to the new conditions [31, 37, 38].…”

Section: Introductionmentioning

confidence: 99%

“…Temperature induced drought however, can inhibit N 2 fixation rates, especially cyanobacterial N 2 fixation [9, 24, 31–36]. Temperature effects on N 2 fixation rates might also be influenced by physiological adaptation of diazotrophic communities, or shifts to a species composition better suited to the new conditions [31, 37, 38]. Despite the importance of microbial communities for plant functioning and ecosystem processes, the effect of warming on moss microbial communities has received little attention.…”

Section: Introductionmentioning

confidence: 99%

Long-term warming effects on the microbiome and nitrogen fixation of a common moss species in sub-Arctic tundra

Klarenberg

Keuschnig

Colmenares

et al. 2019

Preprint

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Bacterial communities form the basis of biogeochemical processes and determine plant growth and health. Mosses, an abundant plant group in many Arctic ecosystems, harbour diverse bacterial communities that are for instance involved in nitrogen fixation. Global climate change is causing changes in aboveground plant biomass and shifting species composition in the Arctic, but little is known about the response of the moss microbiome. Here, we study the bacterial community associated with the moss Racomitrium lanuginosum, a common species in the Arctic, in a 20-year in situ warming experiment in an Icelandic heathland. We evaluate changes in bacterial community composition and diversity. Further, we assess the consequences of warming for nifH gene copy numbers and nitrogen fixation rates. Our findings indicate an increase in the relative abundance of Proteobacteria and a decrease in the relative abundance of Cyanobacteria and Acidobacteria with warming. The nifH gene copy number decreases, while the rate of nitrogen fixation is not affected. This contradiction could be explained by a shift in the nitrogen fixing bacterial community. Although climate warming might not change the contribution of R. lanuginosum to nitrogen input in nitrogen-limited ecosystems, the microbial community resilience and the nitrogen fixing taxa may shift.

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“…In Arctic ecosystems, N2 fixation is known as the major N input into ecosystems (Granhall and Selander, 1973;Rousk et al, 2017Rousk et al, , 2018 with N fixation rates between 1 and 29 kg N ha -1 a -1 , depending on which N2 fixing species (e.g. free-living or moss-associated cyanobacteria) is dominating (Rousk et al, 2017).…”

Section: Molecular and Isotopic Analyses Confirm The Differences In Tmentioning

confidence: 99%

From fibrous plant residues to mineral-associated organic carbon – the fate of organic matter in Arctic permafrost soils

Prater¹,

Zubrzycki²,

Buegger³

et al. 2020

Preprint

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Abstract. Permafrost-affected soils of the Arctic account for 70 % or 727 Pg of the soil organic carbon (C) stored in the permafrost region and therefore play a major role in the global C cycle. Most studies on the budgeting of C storage and the quality of soil organic matter (SOM) in the northern circumpolar region focus on bulk soils. Thus, although there is a plethora of assumptions regarding differences in terms of C turnover or stability, only little knowledge is available on the mechanisms stabilizing organic C in Arctic soils besides impaired decomposition due to low temperatures. To gain such knowledge, we investigated soils from Samoylov Island in the Lena River Delta with respect to the composition and distribution of organic C among differently stabilized SOM fractions. The soils were fractionated according to density and particle size to obtain differently stabilized SOM fractions differing in chemical composition and thus bioavailability. To better understand the chemical alterations from plant-derived organic particles in these soils rich in fibrous plant residues to mineral-associated SOM, we analysed the elemental, isotopic and chemical composition of particulate OM (POM) and clay-sized mineral-associated OM (MAOM). We demonstrate that the SOM fractions that contribute with about 17 kg C m−3 for more than 60 % of the C stock are highly bioaccessible and that most of this labile C can be assumed to be prone to mineralization under warming conditions. Thus, the amount of relatively stable, small occluded POM and clay-sized MAOM that account currently with about 10 kg C m−3 for about 40 % of the C stock will most probably be crucial for the quantity of C protected from mineralization in these Arctic soils in a warmer future. Using δ15N as proxy for nitrogen (N) balances indicated an important role of N inputs by biological N fixation, while gaseous N losses appeared less important. However, this could change, as with about 0.4 kg N m−3 one third of the N is present in bioaccessible SOM fractions, which could lead to increases in mineral N cycling and associated N losses under global warming. Our results highlight the vulnerability of SOM in Arctic permafrost-affected soils under rising temperatures, potentially leading to unparalleled greenhouse gas emissions from these soils.

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What drives biological nitrogen fixation in high arctic tundra: Moisture or temperature?

Cited by 54 publications

References 52 publications

Faster nitrogen cycling and more fungal and root biomass in cold ecosystems under experimental warming: a meta‐analysis

Faster nitrogen cycling and more fungal and root biomass in cold ecosystems under experimental warming: a meta‐analysis

Long-term warming effects on the microbiome and nitrogen fixation of a common moss species in sub-Arctic tundra

From fibrous plant residues to mineral-associated organic carbon – the fate of organic matter in Arctic permafrost soils

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