Functional shifts in unvegetated, perhumid, recently-deglaciated soils do not correlate with shifts in soil bacterial community composition.


Journal Article

Past work in recently deglaciated soils demonstrates that microbial communities undergo shifts prior to plant colonization. To date, most studies have focused on relatively 'long' chronosequences with the ability to sample plant-free sites over at least 50 years of development. However, some recently deglaciated soils feature rapid plant colonization and questions remain about the relative rate of change in the microbial community in the unvegetated soils of these chronosequences. Thus, we investigated the forelands of the Mendenhall Glacier near Juneau, AK, USA, where plants rapidly establish. We collected unvegetated samples representing soils that had been ice-free for 0, 1, 4, and 8 years. Total nitrogen (N) ranged from 0.00 approximately 0.14 mg/g soil, soil organic carbon pools ranged from 0.6 approximately 2.3 mg/g soil, and both decreased in concentration between the 0 and 4 yr soils. Biologically available phosphorus (P) and pH underwent similar dynamics. However, both pH and available P increased in the 8 yr soils. Nitrogen fixation was nearly undetectable in the most recently exposed soils, and increased in the 8 yr soils to approximately 5 ng N fixed/cm(2)/h, a trend that was matched by the activity of the soil N-cycling enzymes urease and beta-l,4-N-acetyl-glucosa-minidase. 16S rRNA gene clone libraries revealed no significant differences between the 0 and 8 yr soils; however, 8 yr soils featured the presence of cyanobacteria, a division wholly absent from the 0 yr soils. Taken together, our results suggest that microbes are consuming allochtonous organic matter sources in the most recently exposed soils. Once this carbon source is depleted, a competitive advantage may be ceded to microbes not reliant on in situ nutrient sources.

Full Text

Cited Authors

  • Sattin, SR; Cleveland, CC; Hood, E; Reed, SC; King, AJ; Schmidt, SK; Robeson, MS; Ascarrunz, N; Nemergut, DR

Published Date

  • December 2009

Published In

Volume / Issue

  • 47 / 6

Start / End Page

  • 673 - 681

PubMed ID

  • 20127458

Pubmed Central ID

  • 20127458

Electronic International Standard Serial Number (EISSN)

  • 1976-3794

International Standard Serial Number (ISSN)

  • 1225-8873

Digital Object Identifier (DOI)

  • 10.1007/s12275-009-0194-7


  • eng