Nine years of CO₂ enrichment at the alpine treeline stimulates soil respiration but does not alter soil microbial communities

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• 作者：Frank Hagedorn^a ; ^{hagedorn@wsl.ch} ; ^{frank.hagedorn@wsl.ch} ; David Hiltbrunner^a ; Kathrin Streit^b ; Alf Ekblad^c ; Bjö ; rn Lindahl^d ; Anja Miltner^e ; Beat Frey^a ; I. Tanya Handa^f ; Stephan Hä ; ttenschwiler^f
• 关键词：Carbon cycling ; Elevated CO2 ; Fungi ; PLFA ; Microbial community ; Soil respiration ; Isotope tracing ; Treeline ; Tree species
• 刊名：Soil Biology & Biochemistry
• 出版年：2013
• 出版时间：February, 2013
• 年：2013
• 卷：57
• 期：Complete
• 页码：390-400
• 全文大小：485 K

文摘

Elevated atmospheric CO₂ was often shown to stimulate belowground C allocation, but it is uncertain if this increase also alters the structure of soil microbial communities. Here, we assessed the effects of nine years of CO₂ enrichment on soil microbial communities of an alpine treeline ecosystem with 35-year-old Larix decidua and Pinus mugo ssp. uncinata trees. We also tracked the ¹³C signal of supplemental CO₂ in soil-respired CO₂, microbial biomass, and phospholipid fatty acids (PLFA) in undisturbed mor-type organic layers. We found a persistently increased soil CO₂ efflux (+24 % on average), but negligible effects of elevated CO₂ on the biomass and community structure of soil microorganisms under both tree species determined with PLFA and T-RFLP (terminal restriction fragment length polymorphism). The ¹³C tracing over 9 years revealed that 24-40 % of the soil microbial biomass was composed of ¡®new¡¯ plant-derived C. PLFA from gram-negative biomarkers did not significant shift in ¹³C by the CO₂ addition, while those of gram-negative bacteria were significantly altered. The highest ¹³C signals in individual PLFA was found in the fatty acid 18:2¦Ø6,9 with 65-80 % new C, indicating that new plant-derived C was primarily incorporated by soil fungi. However, CO₂ enrichment did not affect the production of mycelia biomass and the structure and composition of the fungal communities analysed by high-throughput 454-sequencing of genetic markers. Collectively, our results suggest that C flux through the plant-soil system will be accelerated but that the biomass and composition of microbial communities will be little affected by rising atmospheric CO₂ in organic matter rich treeline soils.