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Wind Cave (WICA) in the Black Hills of South Dakota, like many mostly dry caves in temperate regions is an energy-starved system.The biotic communities that reside in these systems are low in diversity and simple in structure, and sensitive to changes in externalinputs of organic matter. Caves open to tourist traffic offer an opportunity to study the impacts of organic matter amendments in theform of human and rodent hair and dander, clothing lint, material from rodent activity (nesting materials and feces), and algal growthin and around artificial lighting. This study reports on the impacts of carbon amendments from humans and rodents on the bacterialand archaeal communities within the sediments of WICA from annual surveys and from a manipulative study that added lint (‘L’;cellulose plus rodent dander and rodent hair), rodent feces (‘F’), and a combination of both (‘LF’). The survey confirmed that bacterialbiomass was higher in regions of the cave with the highest rates of lint (hair and natural clothing fibers) input. The manipulative studyfound that organic amendments in the forms of lint (L) and rodent feces (F) altered the WICA bacterial community structure in bothabundance and diversity, with the combined lint and feces (LF) amendment having the most significant response. The high similarityof the LF and L communities suggests that the cave bacterial community is more carbon than nitrogen limited. The implication ofcave development to management practices is immediate and practical. Even small amounts of lint and organic matter foreign tocave bacteria significantly compromise the integrity of the endemic community resulting in the replacement of undescribed speciesby assemblages with at best, unknown impacts to natural cave features.

High latitudes contain nearly half of global soil carbon, prompting interest in understanding how the Arctic terrestrial carbon balance will respond to rising temperatures (1,2). Low temperatures suppress the activity [...]

We examined the effect of reduced tillage on the accumulation of fungal-versus bacterial-derived organic matter within the soil matrix by quantifying the amino sugars glucosamine (Glc), galactosamine (Gal), and muramic acid (MurA) in aggregate-size fractions isolated from no-tillage (NT) and conventional-tillage (CT) soil. Intact soil cores (0- to 5- and 5- to 20-cm depth) were collected from the long-term tillage experiment at Horseshoe Bend in Athens, GA. Four water-stable aggregate-size fractions were isolated: large macroaggregates (>2000 [micro]m), small macroaggregates (250-2000 [micro]m), microaggregates (53-250 [micro]m), and the silt + clay fraction (250 [micro]m), microaggregates contained within macroaggregates, and the silt + clay fraction. Amino sugars were extracted from all fractions, purified, and analyzed by gas chromatography. Fungal-derived amino sugar C (FAS-C) comprised 63%, while bacterial-derived amino sugar C (BAS-C) accounted for 37% of the total amino sugar C pool under both tillage treatments. No-tillage soil contained 21% more amino sugar C than the CT soil across the entire plow layer. Both, the percentage of total organic C as FAS-C and BAS-C were significantly higher in the silt + clay fraction of NT versus CT soil. The percentage of total organic C as FAS-C was significantly higher in small macroaggregates of NT versus CT soil due to a preferential accumulation of FAS-C in the microaggregates contained within these macroaggregates. These results indicate that microbial-derived C is stabilized in NT soils, due primarily to a greater fungal-mediated improvement of soil structural stability and concurrent deposition of fungal-derived C in microaggregates contained within macroaggregates.