Liang and Balser 2008

Liang C, Balser TC. 2008. Preferential sequestration of microbial carbon in subsoils of a glacial-landscape toposequence, Dane County, WI, USA. Geoderma 148: 113-119.

These authors examined the microbial communities at a range of depths in soils near the University of Wisconsin, Madison campus. Soil organic carbon includes markers of microbial groups such as amino sugars, molecules that are absent from plants and specific to some groups of soil microorganisms. As markers, these molecules have several advantages; besides their utility in identifying organisms, they are stable in soils, persist after cell depth, and can apparently be extracted and examined using fairly simple laboratory techniques plus access to a gas chromatograph.

This study represents a general survey of soil carbon in this system, an examination of the pools and fates of different carbon molecule classes as well as the contributions of broad groups such as bacteria and fungi to soil physiology in different soil horizons. There were three main conclusions:
1. Upper soil horizons are relatively enriched both in total SOC and amino sugars. The source of this material almost certainly is some combination of surface plant litter and root exudates, not surprisingly supporting a large community of microorganisms in the near-surface soil.
2. Amino sugars accumulate in subsoils, despite the redox environment (presumably somewhat negative) associated with the water table.
3. Amino sugars, while useful, are not sufficient on their own to elucidate mechanisms of SOC turnover and sequestration by soil microbes. Variability between sites and between horizons suggests a major role of both history and site-specific factors in structuring communities at a level distinguishable by ratios of various amino sugars.

This paper is one of a handful I have that explicitly examine microbial communities and variation by depth. However, as this paper describes what I think is a first-look at a soil microbiological system, it lacks some detail and strong conclusions. Amino sugars may be useful in my own research, though I think our lab has more familiarity with other techniques useful for examining interactions between soil bacteria and fungi.

Beyond my current research, this paper is clearly written, not too long, and presents a set of well-described investigations built on a solid foundation of general theory. This suggests it may be useful as a teaching tool, perhaps as a paper a 2nd-year undergraduate would have the skills and knowledge to understand.