Publications by authors named "David S Duncan"
Associative N fixation (ANF), the process by which dinitrogen gas is converted to ammonia by bacteria in casual association with plants, has not been well-studied in temperate ecosystems. We examined the ANF potential of switchgrass (Panicum virgatum L.), a North American prairie grass whose productivity is often unresponsive to N fertilizer addition, via separate short-term 15N2 incubations of rhizosphere soils and excised roots four times during the growing season.
View Article and Find Full Text PDFMicrobial communities are important drivers and regulators of ecosystem processes. To understand how management of ecosystems may affect microbial communities, a relatively precise but effort-intensive technique to assay microbial community composition is phospholipid fatty acid (PLFA) analysis. PLFA was developed to analyze phospholipid biomarkers, which can be used as indicators of microbial biomass and the composition of broad functional groups of fungi and bacteria.
View Article and Find Full Text PDFArticle Synopsis
- Nitrogen fertilization can boost plant growth but must be managed wisely to prevent environmental harm from N loss.
- A study compared how different planting systems—switchgrass monoculture, a 5-species mix, and an 18-species prairie—reacted to N fertilization over two years.
- Results showed higher N2O emissions and nitrate levels in the switchgrass, while polycultures had increased productivity with less N loss, demonstrating their favorable response to fertilization compared to monocultures.
It is well established that soil microbial communities change in response to altered land use and land cover, but less is known about the timing of these changes. Understanding temporal patterns in recovering microbial communities is an important part of improving how we assess and manage reconstructed ecosystems. We assessed patterns of community-level microbial diversity and abundance in corn and prairie plots 2 to 4 years after establishment in agricultural fields, using phospholipid fatty acid biomarkers.
View Article and Find Full Text PDFObjective: To determine the accuracy of multidetector computed tomography (MDCT) in the diagnosis of nonocclusive mesenteric ischaemia (NOMI) among patients after cardiovascular surgery.
Design, Setting And Participants: A retrospective review of 38 patients in a cardiothoracic intensive care unit who underwent MDCT examination before laparotomy for suspected NOMI between January 2001 and December 2012.
Intervention And Main Outcome Measures: The MDCT studies were examined independently by three radiologists, who were asked to make a determination on the presence or absence of NOMI.