Fig. 2.
Annual course of cross-sectional electrical resistivity (ER). a ER tomograms of the trunk of a representative P. cembra tree measured at five different dates in Praxmar, Austria (1700 m a.s.l.). Areas of high ER are indicated by red color while areas of low resistivity are indicated by blue color. Note that the limit of the displayed resistivity ranges was set manually (80–400 Ωm) to optimize visualization, and ERmin and ERmax values may exceed these limits. b Mean electrical resistivity (ERmean) measured from September 2012 to September 2013 on four P. cembra trees. Red dots indicate measurement dates of tomograms in a. c Air (open circles) and xylem temperatures (close triangles) during ER measurements [average values (1 h) were calculated for the time at which ER measurements were performed]. Mean ± SE