Etude de la résistance électrique du cambium dans les épicéas (Picea abies L.) dépérissants

Abstract

Simultaneously, the influence of a number of factors (position of the electrodes on the trunk, number of measurements, diameter of the tree and external conditions) was evaluated.In healthy spruce, it appears that resistance increases when the diameter of the trees decreases, and that this relation between resistance and diameter depends on the stand (influence of soil fertility ?).In declining spruce, we show that this phenomenon leads to a significant increase in cambial electrical resistance, and that the smaller the diameter of the spruce, the more important this increase is. This study points out that the cambial electrical resistance measurements corroborate the results provided by conventional methods (rate of needle loss), but by quantifying, specifying and magnifying them. Therefore the cambial electrical resistance measurements can be used in symptomatology to provide a rapid assessment in the field of the dec7ree of vitality in declining spruce over time.cambial electrical resistance -spruce -decline -symptomato,logy

Variations in bark acidity and conductivity over the trunk length of silver fir and Norway spruce

“…Other ions are also involved, such as PO4 3-, Mg 2+ and Ca 2+ . According to Garrec (Garrec et al 1989), the cambial electrical resistance (opposite to conductance) depends essentially on the presence of mobile ions, mainly K + . Moreover, it has been proved that mineral substances absorbed by roots could partially transit from xylem to phloem and even to bark (Heller 1969;Walkenhorst et al 1993).…”