TY - JOUR
T1 - Functional shifts in unvegetated, perhumid, recently-deglaciated soils do not correlate with shifts in soil bacterial community composition
AU - Sattin, Sarah R.
AU - Cleveland, Cory C.
AU - Hood, Eran
AU - Reed, Sasha C.
AU - King, Andrew J.
AU - Schmidt, Steven K.
AU - Robeson, Michael S.
AU - Ascarrunz, Nataly
AU - Nemergut, Diana R.
N1 - Funding Information:
The authors wish to thank Logan Berner for assistance with fieldwork, Alan Townsend for valuable discussions and several anonymous reviewers for their thoughtful insights. We also thank the staff of the USFS Mendenhall Glacier Visitor’s Center for providing access to field sites. This work was partially supported by a grant from the Microbial Observatories Program (MCB-0455606) of the National Science Foundation.
PY - 2009/12
Y1 - 2009/12
N2 - 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 0.00~0.14 mg/g soil, soil organic carbon pools ranged from 0.6~2.3 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 ~5 ng N fixed/cm2/h, a trend that was matched by the activity of the soil N-cycling enzymes urease and β-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.
AB - 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 0.00~0.14 mg/g soil, soil organic carbon pools ranged from 0.6~2.3 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 ~5 ng N fixed/cm2/h, a trend that was matched by the activity of the soil N-cycling enzymes urease and β-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.
KW - Microbial community structure
KW - N fixation
KW - Soil enzyme activity
KW - Succession
UR - http://www.scopus.com/inward/record.url?scp=75949120249&partnerID=8YFLogxK
U2 - 10.1007/s12275-009-0194-7
DO - 10.1007/s12275-009-0194-7
M3 - Article
AN - SCOPUS:75949120249
SN - 1225-8873
VL - 47
SP - 673
EP - 681
JO - Journal of Microbiology
JF - Journal of Microbiology
IS - 6
ER -