title: Responses of aerobic microbial communities and soil respiration to water-level drawdown in a northern boreal fen.
abstract: On a global basis, peatlands are a major reserve of carbon (C). Hydrological changes can affect the decomposition processes in peatlands and in turn can alter their C balance. Since 1959, a groundwater extraction plant has generated a water-level gradient at our study site that has gradually changed part of the wet fen into a dry peatland forest. The average water-level drawdown of the gradient (from a pristine 9 cm to 26 cm in the dry end) is close to an estimate predicted by an increase in mean global temperature of 3 degrees C. We studied the total microbial community of the aerobic surface peat in four locations along the gradient through phospholipid fatty acid and PCR-DGGE methods. Additionally, field measurements of soil respiration showed a threefold increase in the C-emission rate at the driest location compared with the wettest one, indicating enhanced decomposition. Also, both fungal and bacterial biomass increased in the drier locations. At the species level, the fungal community changed due to water-level drawdown whereas actinobacteria were less sensitive to drying. The majority of fungal sequences were similar to ectomycorrhizal (ECM) fungi, which dominated throughout the gradient. Our results indicate that ECM fungi might act as important facultative decomposers in organic-rich environments such as peatlands.
authors: Finnish Forest Research Institute, Vantaa Research Unit, PO Box 18, 01301 Vantaa, Finland. krista.peltoniemi@metla.fi
authors: Krista
authors: K
authors: Jaatinen
authors: Raija
authors: R
authors: Laiho
authors: Anita
authors: A
authors: Vuorenmaa
authors: Urko
authors: U
authors: del Castillo
authors: Kari
authors: K
authors: Minkkinen
authors: Taina
authors: T
authors: Pennanen
authors: Timo
authors: T
authors: Penttilä
authors: Hannu
authors: H
authors: Fritze
mesh_terms: D039903:Actinobacteria / Q000145:classification / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification; D000332:Aerobiosis; D004269:DNA, Bacterial / Q000032:analysis; D004271:DNA, Fungal / Q000032:analysis; D021903:DNA, Ribosomal Spacer / Q000032:analysis; D017753:Ecosystem; D004587:Electrophoresis, Agar Gel; D005227:Fatty Acids / Q000032:analysis; D005658:Fungi / Q000145:classification / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D010101:Oxygen Consumption; D010743:Phospholipids / Q000032:analysis; D016133:Polymerase Chain Reaction; D025341:Principal Component Analysis; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012987:Soil / Q000032:analysis*; D012988:Soil Microbiology; D014867:Water
chemical_list: D004269:DNA, Bacterial; D004271:DNA, Fungal; D021903:DNA, Ribosomal Spacer; D005227:Fatty Acids; D010743:Phospholipids; D012336:RNA, Ribosomal, 16S; D012987:Soil; D014867:Water