Fire vs. Metal: A Laboratory Study Demonstrating Microbial Responses to Soil Disturbances

Autor/in	Stromberger, Mary E.
Titel	Fire vs. Metal: A Laboratory Study Demonstrating Microbial Responses to Soil Disturbances
Quelle	In: Journal of Natural Resources and Life Sciences Education, 34 (2005), S.1-7 (7 Seiten) PDF als Volltext Verfügbarkeit
Sprache	englisch
Dokumenttyp	gedruckt; online; Zeitschriftenaufsatz
ISSN	1059-9053
Schlagwörter	Leitfaden; Unterricht; Lehrer; Microbiology; Science Laboratories; Ecology; Soil Science; College Students; Environmental Research; Scientific Research; Discussion; Student Reaction; Teaching Methods; Experiential Learning; Colorado + Suchen Sie Ihr Suchwort? Lesson concept; Instruction; Unterrichtsentwurf; Unterrichtsprozess; Teacher; Teachers; Lehrerin; Lehrende; Mikrobiologie; Ökologie; Bodenkunde; Collegestudent; Environmental study; Umweltforschung; Diskussion; Schülerkritik; Teaching method; Lehrmethode; Unterrichtsmethode; Experiental learning; Erfahrungsorientiertes Lernen
Abstract	Incubation studies are traditionally used in soil microbiology laboratory classes to demonstrate microbial respiration and N mineralization-immobilization processes. Sometimes these exercises are done to calculate a N balance in N fertilizer-amended soils. However, examining microbial responses to environmental perturbations would appeal to soil microbiology students with broader interests in ecology and environmental soil science. In this study, perturbations of fire and heavy metal inputs were used to demonstrate disturbance impacts on microbial respiration and N mineralization, soil [beta]-glucosidase activity, and abundance of soil bacteria and fungi in a series of exercises lasting 28 days. Students constructed duplicate microcosms containing pristine forest soil or forest soil burned by fires varying in severity or polluted with CuCl[subscript 2]. During a 2-week period, students measured changes in soil pH, CO[subscript 2] evolution by the NaOH-trap method, and extractable soil NH[subscript 4]-N and NO[subscript 3]-N content. After 2 weeks, students tested for [beta]-glucosidase activity and preserved samples for enumeration of total bacteria and fungi. Direct counts of bacteria and fungi were conducted on the third week by epifluorescence and phase contrast microscopy, but alternative methods to assess microbial biomass can be employed. Respiration was determined on the fourth week by titration of NaOH vials. After completion of the exercises, students had an appreciation of microbial responses to different types of disturbances, as measured by multiple biological parameters. Because this study was repeated over 2 years, students in the second year were able to assess soil microbial recovery immediately and 1 year after a forest fire. This study could easily be adapted for other types of disturbance issues, including salinity, land application of waste materials, and contamination of soil by xenobiotics. (Contains 6 tables.) (Author).
Anmerkungen	American Society of Agronomy. 677 South Segoe Road, Madison, WI 53711. Tel: 608-273-8080; Fax: 608-273-2021; Web site: http://www.jnrlse.org/
Erfasst von	ERIC (Education Resources Information Center), Washington, DC
Update	2017/4/10