Estimating the absorptive root area in Norway spruce by using the common direct and indirect earth impedance methods

0393214 - ÚVGZ 2014 RIV NL eng J - Journal Article
Čermák, J. - Cudlín, Pavel - Gebauer, R. - Borja, I. - Martinková, M. - Staněk, Z. - Koller, J. - Neruda, J. - Nadezhdina, N.
Estimating the absorptive root area in Norway spruce by using the common direct and indirect earth impedance methods.
Plant and Soil. Roč. 372, 1-2 (2013), s. 401-415. ISSN 0032-079X. E-ISSN 1573-5036
R&D Projects: GA MŠMT(CZ) ED1.1.00/02.0073; GA MŠMT OC10023
Institutional support: RVO:67179843
Keywords : Active absorptive fine root area index * Fine root surface * Modified earth impedance * Picea abies * Root research methods
Subject RIV: EH - Ecology, Behaviour
Impact factor: 3.235, year: 2013

Estimates of root absorption magnitude are needed for the balanced management of forest ecosystems, but no methods able to work on the whole tree and stand level were available. Modified earth impedance method was developed recently and here it was tested, by comparing the results with those obtained by combination of several classical methods. We used direct (soil cores, scanning and microscopy) and indirect (sap flow patterns and modified earth impedance) methods in an attempt to estimate the absorptive root area indexes (RAI) at two sites of about 25 and 40-years-old Norway spruce. We considered the geometric surfaces of all scanned fine roots to be equal to the fine root absorptive area (RAI scan ). To estimate the potentially physically permeable area of fine roots, we microscopically evaluated the point of secondary xylem appearance and calculated the geometric area of root portions with primary structure (RAI micro ). We termed the area of electrically conductive root surface as the active (ion) absorptive area (RAI mei ) and measured its extent by the modified earth impedance (MEI) method. The highest values for absorptive root areas at the two experimental sites we obtained with the scanning method (RAI scan was considered to be 100%), followed by the RAI micro (51%) and RAI mei (32%). RAImei reached about 2/3 of RAImicro. The surface area of the ectomycorrhizal hyphae was an order of magnitude larger than that of all fine roots, but the MEI did not measure such increase. We showed that the absorptive root area, indirectly estimated by the MEI, provides consistent results that approach the values obtained for fine roots with a primary structure estimated by traditional direct methods. The similar range of the values for the absorptive root surface area obtained by microscopy and by the MEI method indicates that this method is feasible and that it could be used to determine the extent of active absorptive root surface areas in forests.
Permanent Link: http://hdl.handle.net/11104/0221966