caa a22 4500 477110401 CHVBK 20180405111607.0 cr unu---uuuuu 170330e19960101xx s 000 0 eng 10.1007/BF00011161 doi (NATIONALLICENCE)springer-10.1007/BF00011161 Soil aeration in relation to soil physical properties, nitrogen availability, and root characteristics within an arctic watershed [Elektronische Daten] [Renate Gebauer, John Tenhunen, James Reynolds] The seasonal change in soil oxygen availability was determined in several habitats along a topographic moisture gradient in an arctic watershed. The effect of changes in soil aeration on soil chemical and plant properties was examined by comparison of the driest (tussocks) and wettest (wet sedge tundra) sites along this gradient. Spatial variability and seasonal change in soil oxygen availability was closely linked to the hydrologic regime and the thickness of the organic soil horizon. The greatest extension of the aerobic soil layer was found beneath well-drained tussocks, while less than 10% of the unfrozen soil layer is aerated in flooded wet sedge tundra. Intertussock areas and watertracks (channels of water drainage) have intermediate levels of aeration. In tussock tundra, soil oxygen diffusion is restricted in the mineral soil layer below the organic horizon due to reduced pore space. Organic matter constituents and their change with depth were similar beneath tussocks and in wet sedge tundra, indicating that factors other than soil aeration (e.g. low soil temperatures, short growing season) are the primary controls on decomposition in these two arctic tundra systems. NH4 +, the dominant form of inorganic N, was more available in wet sedge tundra than in tussock tundra. At both sites, extractable and soil solution NO3 - concentrations increased 4 to 8 fold in the second part of the growing season, indicating increased nitrifier activity with improved soil oxygen availability. Although soils thawed as deep as 60 cm, approx. 90% of the root biomass was concentrated within 20 cm of the surface. Despite the anaerobic soil environment in wet sedge tundra, the dominant species there, Eriophorum angustifolium, reached slightly greater rooting depths than E. vaginatum, whose roots grow in the elevated, aerobic portion of tussocks. E. angustifolium had a root porosity of 31%, within the range found for wetland species, while roots of E. vaginatum had a porosity close to 12%. Rhizome porosity were low in both species (11%). Kluwer Academic Publishers, 1996 anaerobic nationallicence N availability nationallicence permafrost nationallicence tundra nationallicence tussock nationallicence Gebauer Renate Department of Biology, San Diego State University, 92182, San Diego, CA, USA aut Tenhunen John BITÖK, Universität Bayreuth, Dr. Hans Frisch Str. 1-3, D-95440, Bayreuth, Germany aut Reynolds James Department of Biology, San Diego State University, 92182, San Diego, CA, USA aut Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl 178/1(1996-01-01), 37-48 0032-079X 178:1<37 1996 178 11104 https://doi.org/10.1007/BF00011161 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00011161 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Gebauer Renate Department of Biology, San Diego State University, 92182, San Diego, CA, USA aut NATIONALLICENCE 700 1- Tenhunen John BITÖK, Universität Bayreuth, Dr. Hans Frisch Str. 1-3, D-95440, Bayreuth, Germany aut NATIONALLICENCE 700 1- Reynolds James Department of Biology, San Diego State University, 92182, San Diego, CA, USA aut NATIONALLICENCE 773 0- Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl/ 178/1(1996-01-01), 37-48 0032-079X 178:1<37 1996 178 11104 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer