Anthropogenic nitrogen enrichment enhances soil carbon accumulation by impacting saprotrophs rather than ectomycorrhizal fungal activity.

Autor: Maaroufi NI; Institute of Plant Sciences, University of Bern, Bern, Switzerland.; Department of Forest Ecology and Management, Swedish University of Agriculture Sciences, Umeå, Sweden.; Department of Forest Mycology and Plant Pathology, BioCenter, Swedish University of Agricultural Sciences, Uppsala, Sweden., Nordin A; Department of Forest Genetics and Plant Physiology, Umeå Plant Science Center, Swedish University of Agricultural Sciences, Umeå, Sweden., Palmqvist K; Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden., Hasselquist NJ; Department of Forest Ecology and Management, Swedish University of Agriculture Sciences, Umeå, Sweden., Forsmark B; Department of Forest Ecology and Management, Swedish University of Agriculture Sciences, Umeå, Sweden., Rosenstock NP; Center for Environmental and Climate Research, Lund University, Lund, Sweden., Wallander H; Department of Microbial Ecology, Lund University, Lund, Sweden., Gundale MJ; Department of Forest Ecology and Management, Swedish University of Agriculture Sciences, Umeå, Sweden.
Jazyk: angličtina
Zdroj: Global change biology [Glob Chang Biol] 2019 Sep; Vol. 25 (9), pp. 2900-2914. Date of Electronic Publication: 2019 Jul 10.
DOI: 10.1111/gcb.14722
Abstrakt: There is evidence that anthropogenic nitrogen (N) deposition enhances carbon (C) sequestration in boreal forest soils. However, it is unclear how free-living saprotrophs (bacteria and fungi, SAP) and ectomycorrhizal (EM) fungi responses to N addition impact soil C dynamics. Our aim was to investigate how SAP and EM communities are impacted by N enrichment and to estimate whether these changes influence decay of litter and humus. We conducted a long-term experiment in northern Sweden, maintained since 2004, consisting of ambient, low N additions (0, 3, 6, and 12 kg N ha -1  year -1 ) simulating current N deposition rates in the boreal region, as well as a high N addition (50 kg N ha -1  year -1 ). Our data showed that long-term N enrichment impeded mass loss of litter, but not of humus, and only in response to the highest N addition treatment. Furthermore, our data showed that EM fungi reduced the mass of N and P in both substrates during the incubation period compared to when only SAP organisms were present. Low N additions had no effect on microbial community structure, while the high N addition decreased fungal and bacterial biomasses and altered EM fungi and SAP community composition. Actinomycetes were the only bacterial SAP to show increased biomass in response to the highest N addition. These results provide a mechanistic understanding of how anthropogenic N enrichment can influence soil C accumulation rates and suggest that current N deposition rates in the boreal region (≤12 kg N ha -1  year -1 ) are likely to have a minor impact on the soil microbial community and the decomposition of humus and litter.
(© 2019 John Wiley & Sons Ltd.)
Databáze: MEDLINE
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