Succession of N cycling processes in biological soil crusts on a Central European inland dune

Brankatschk, Robert; Fischer, Thomas; Veste, Maik; Zeyer, Josef

doi:10.1111/j.1574-6941.2012.01459.x

Cited by 62 publications

(58 citation statements)

References 65 publications

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“…Further investigations comprising multiple nitrogen compounds and isotopes should unravel the interplay of different chemical and biological species and processes in the cycling of nitrogen by biocrusts (33)(34)(35)(36).…”

Section: Resultsmentioning

confidence: 99%

Biological soil crusts accelerate the nitrogen cycle through large NO and HONO emissions in drylands

Weber

Tamm

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

198

188

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Reactive nitrogen species have a strong influence on atmospheric chemistry and climate, tightly coupling the Earth's nitrogen cycle with microbial activity in the biosphere. Their sources, however, are not well constrained, especially in dryland regions accounting for a major fraction of the global land surface. Here, we show that biological soil crusts (biocrusts) are emitters of nitric oxide (NO) and nitrous acid (HONO). Largest fluxes are obtained by dark cyanobacteria-dominated biocrusts, being ∼20 times higher than those of neighboring uncrusted soils. Based on laboratory, field, and satellite measurement data, we obtain a best estimate of ∼1.7 Tg per year for the global emission of reactive nitrogen from biocrusts (1.1 Tg a −1 of NO-N and 0.6 Tg a −1 of HONO-N), corresponding to ∼20% of global nitrogen oxide emissions from soils under natural vegetation. On continental scales, emissions are highest in Africa and South America and lowest in Europe. Our results suggest that dryland emissions of reactive nitrogen are largely driven by biocrusts rather than the underlying soil. They help to explain enigmatic discrepancies between measurement and modeling approaches of global reactive nitrogen emissions. As the emissions of biocrusts strongly depend on precipitation events, climate change affecting the distribution and frequency of precipitation may have a strong impact on terrestrial emissions of reactive nitrogen and related climate feedback effects. Because biocrusts also account for a large fraction of global terrestrial biological nitrogen fixation, their impacts should be further quantified and included in regional and global models of air chemistry, biogeochemistry, and climate.biological soil crusts | nitric oxide | nitrous acid | nitrogen | trace gas emission

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Section: Resultsmentioning

confidence: 99%

Biological soil crusts accelerate the nitrogen cycle through large NO and HONO emissions in drylands

Weber

Tamm

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

198

188

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“…Regarding biological soil crusts, several studies analysed denitrification rates to be negligible (Johnson et al, 2007;Strauss et al, 2012), and N 2 O production was calculated to constitute only 3-4 % of the N fixation rate (Barger et al, 2013). Other studies, however, described high denitrification rates that either increased (Brankatschk et al, 2013) or decreased with advancing crust development (Abed et al, 2013). One possibility to increase the reliability of large-scale estimates of N 2 O emissions by lichens and bryophytes is the application of alternative, methodically different approaches.…”

Section: Introductionmentioning

confidence: 99%

Estimating global nitrous oxide emissions by lichens and bryophytes with a process-based productivity model

et al. 2017

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Abstract. Nitrous oxide is a strong greenhouse gas and atmospheric ozone-depleting agent which is largely emitted by soils. Recently, lichens and bryophytes have also been shown to release significant amounts of nitrous oxide. This finding relies on ecosystem-scale estimates of net primary productivity of lichens and bryophytes, which are converted to nitrous oxide emissions by empirical relationships between productivity and respiration, as well as between respiration and nitrous oxide release. Here we obtain an alternative estimate of nitrous oxide emissions which is based on a global process-based non-vascular vegetation model of lichens and bryophytes. The model quantifies photosynthesis and respiration of lichens and bryophytes directly as a function of environmental conditions, such as light and temperature. Nitrous oxide emissions are then derived from simulated respiration assuming a fixed relationship between the two fluxes. This approach yields a global estimate of 0.27 (0.19-0.35) (Tg N 2 O) year −1 released by lichens and bryophytes. This is lower than previous estimates but corresponds to about 50 % of the atmospheric deposition of nitrous oxide into the oceans or 25 % of the atmospheric deposition on land. Uncertainty in our simulated estimate results from large variation in emission rates due to both physiological differences between species and spatial heterogeneity of climatic conditions. To constrain our predictions, combined online gas exchange measurements of respiration and nitrous oxide emissions may be helpful.

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“…Denitrification rates within surface soils (i.e., top 1 cm) containing biocrusts were negligible relative to other N loss pathways (Johnson et al 2007;Strauss et al 2012) or increased with biocrust development (Brankatschk et al 2013). These studies, however, evaluated denitrification from biologically crusted soils at a single temperature and soil moisture level, environmental conditions that may strongly influence not only N fixation but also denitrification rates.…”

Section: Introductionmentioning

confidence: 99%

“…These pulsed dynamics in soils may result in N "leakage" by biological soil crust organisms to the surrounding soil environment in such forms as NH 4 + and other soluble organic nitrogen compounds (Mayland and McIntosh 1966;Johnson et al 2007). Nitrogen leakage from biocrusts may not only enhance soil nutrient availability to support plant growth (Mayland and McIntosh 1966; Harper 1995 but may also be lost from the system via gaseous N loss in transformations related to nitrification and denitrification processes (Zaady 2005;Barger et al 2005;Johnson et al 2007;Strauss et al 2012;Brankatschk et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Denitrification from nitrogen-fixing biologically crusted soils in a cool desert environment, southeast Utah, USA

2013

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Introduction: Nitrogen fixation by microorganisms within biological soil crust ("biocrust") communities provides an important pathway for N inputs in cool desert environments where soil nutrients are low and symbiotic N-fixing plants may be rare. Estimates of N fixation in biocrusts often greatly exceed that of N accretion rates leading to uncertainty regarding N loss pathways. Methods: In this study we examined nitrogen fixation and denitrification rates in biocrust communities that differed in N fixation potential (low N fixation = light cyanobacterial biocrust, high N fixation = dark cyanolichen crust) at four temperature levels (10, 20, 30, 40°C) and four simulated rainfall levels (0.05, 0.2, 0.6, 1 cm rain events) under controlled laboratory conditions. Results: Acetylene reduction rates (AR, an index of N fixation activity) were over six-fold higher in dark crusts relative to light crusts. Dark biocrusts also exhibited eight-fold higher denitrification rates. There was no consistent effect of temperature on denitrification rates, but there was an interactive effect of water addition and crust type. In light crusts, denitrification rates increased with increasing water addition, whereas the highest denitrification rates in dark crusts were observed at the lowest level of water addition. Conclusions: These results suggest that there are no clear and consistent environmental controls on short-term denitrification rates in these biologically crusted soils. Taken together, estimates of denitrification from light and dark biocrusts constituted 3 and 4% of N fixation rates, respectively suggesting that losses as denitrification are not significant relative to N inputs via fixation. This estimate is based on a previously published conversion ratio of ethylene produced to N fixed that is low (0.295), resulting in high estimates of N fixation. If future N fixation studies in biologically crusted soils show that these ratios are closer to the theoretical 3:1 ratio, denitrification may constitute a more significant loss pathway relative to N fixed.

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Succession of N cycling processes in biological soil crusts on a Central European inland dune

Cited by 62 publications

References 65 publications

Biological soil crusts accelerate the nitrogen cycle through large NO and HONO emissions in drylands

Biological soil crusts accelerate the nitrogen cycle through large NO and HONO emissions in drylands

Estimating global nitrous oxide emissions by lichens and bryophytes with a process-based productivity model

Denitrification from nitrogen-fixing biologically crusted soils in a cool desert environment, southeast Utah, USA

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