caa a22 4500 46909625X CHVBK 20180323133031.0 cr unu---uuuuu 170328e19921201xx s 000 0 eng 10.1007/BF00317851 doi (NATIONALLICENCE)springer-10.1007/BF00317851 Environmental effects on CO2 efflux from riparian tundra in the northern foothills of the Brooks Range, Alaska, USA [Elektronische Daten] [S. Oberbauer, C. Gillespie, W. Cheng, R. Gebauer, A. Serra, J. Tenhunen] Summary: Carbon dioxide efflux and soil microenvironmental factors were measured diurnally in Carex aquatilus-and Eriophorum angustifolium-dominated riparian tundra communities to determine the relative importance of soil environmental factors controlling ecosystem carbon dioxide exchange with the atmosphere. Measurements were made weekly between 18 June and 24 July 1990. Diurnal patterns in carbon dioxide efflux were best explained by changes in soil temperature, while seasonal changes in efflux were correlated with changes in depth to water table, depth to frozen soil and soil moisture. Carbon dioxide efflux rates were lowest early in the growing season when high water tables and low soil temperatures limited microbial and root activity. Individual rainfall events that raised the water table were found to strongly reduce carbon dioxide efflux. As the growing season progressed, rainfall was low and depth to water table and soil temperatures increased. In response, carbon dioxide efflux increased strongly, attaining rates late in the season of approximately 10 g CO2 m−2 day−1. These rates are as high as maxima recorded for other arctic sites. A mathematical model is developed which demonstrates that soil temperature and depth to water table may be used as efficient predictors of ecosystem CO2 efflux in this habitat. In parallel with the field measurements of CO2 efflux, microbial respiration was studied in the laboratory as a function of temperature and water content. Estimates of microbial respiration per square meter under field conditions were made by adjusting for potential respiring soil volume as water table changed and using measured soil temperatures. The results indicate that the effect of these factors on microbial respiration may explain a large part of the diurnal and seasonal variation observed in CO2 efflux. As in coastal tundra sites, environmental changes that alter water table depth in riparian tundra communities will have large effects on ecosystem CO2 efflux and carbon balance. Springer-Verlag, 1992 Arctic tundra nationallicence Depth of thaw nationallicence Ecosystem carbon exchange nationallicence Permafrost nationallicence Soil respiration nationallicence Oberbauer S. Department of Biological Sciences, Florida International University, 33199, Miami, FL, USA aut Gillespie C. Systems Ecology Research Group, College of Sciences, San Diego State University, 92182, San Diego, CA, USA aut Cheng W. Systems Ecology Research Group, College of Sciences, San Diego State University, 92182, San Diego, CA, USA aut Gebauer R. Systems Ecology Research Group, College of Sciences, San Diego State University, 92182, San Diego, CA, USA aut Serra A. Systems Ecology Research Group, College of Sciences, San Diego State University, 92182, San Diego, CA, USA aut Tenhunen J. Bayreuther Institut für Ökosystemforschung (BITÖK), Universität Bayreuth, W-8580, Bayreuth, Germany aut Oecologia Springer-Verlag 92/4(1992-12-01), 568-577 0029-8549 92:4<568 1992 92 442 https://doi.org/10.1007/BF00317851 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00317851 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Oberbauer S. Department of Biological Sciences, Florida International University, 33199, Miami, FL, USA aut NATIONALLICENCE 700 1- Gillespie C. Systems Ecology Research Group, College of Sciences, San Diego State University, 92182, San Diego, CA, USA aut NATIONALLICENCE 700 1- Cheng W. Systems Ecology Research Group, College of Sciences, San Diego State University, 92182, San Diego, CA, USA aut NATIONALLICENCE 700 1- Gebauer R. Systems Ecology Research Group, College of Sciences, San Diego State University, 92182, San Diego, CA, USA aut NATIONALLICENCE 700 1- Serra A. Systems Ecology Research Group, College of Sciences, San Diego State University, 92182, San Diego, CA, USA aut NATIONALLICENCE 700 1- Tenhunen J. Bayreuther Institut für Ökosystemforschung (BITÖK), Universität Bayreuth, W-8580, Bayreuth, Germany aut NATIONALLICENCE 773 0- Oecologia Springer-Verlag 92/4(1992-12-01), 568-577 0029-8549 92:4<568 1992 92 442 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer