Electro-diagnostics of trees

Studying the vitality of biological organisms

At present, one of the methods offered by conventional technology in studying the vitality of biological organisms is to measure their electric currents. The electric activities of trees were first measured in 1925, and since the 1960s it has been known that electric potentials reflect the rhythms of day and night, of the seasons, and of the moon. They interact with the air electricity that directly surrounds the tree, and even with the earth’s magnetic field.

Since his pioneering studies of geo-phyto-electrical currents (GPEC) began in 1969, the Czech scientist Vladimir Rajda has become an international expert in this field. … Deciduous trees generally have a clearly higher GPEC than evergreens, and the yew is in-between. The highest levels, 410 micro-Ampere/cm and 936 milliVolt, have been measured in horse chestnuts (Aesculus hippocastanum) and 370 microA/cm and 830mV in oaks (Quercus robur) with 50cm trunk diameter. One of the least GPEC-active trees is Scots pine (Pinus sylvestris) which lives on less than a third of the currents produced in oak. Spruce (Picea abies) values are only slightly higher than pine. The cedar of Lebanon (Cedrus libani), however, during its juvenile stages has similar GPEC values to the yew.

Fluctuations over the seasons

The vitality levels normally increase during the growth of the trees over the years. The annual rhythm shows an annual absolute low point at the turn of the year, and from there an uninterrupted increase of metabolic activity (in healthy plants) until the peak is reached at the end of July. … The curves of deciduous trees rise and fall more sharply than those of conifers because deciduous trees reach much higher levels than evergreens in summer.

The yew however is different. Its annual GPEC curve resembles a mighty dome that spreads from mid-March to mid-December. See both red lines in the graph below. While the short-lived summer maximum levels of deciduous trees only last for a day or two, yew holds its top level (195 microAmpere/cm and 833 mV) for a full two months.

This unique dome-shape for Taxus (Yew) indicates that, although the GPEC in oak around 1 August are about twice as high as those of the yew, the annual averages of those trees are fairly similar. In other words, the annual average energy level of yew is one of the highest among European trees despite it being an evergreen.


As for health, about half of the yews in the Czech Republic showed 100% vitality; the other half, with 83-87%, must be considered physiologically weakened but still range above the country’s average of 68% for the other tree species. The study confirmed the high vitality of Taxus baccata and its significant resistance against environmental pollutants. It also suggests that the high life expectancy of yew is at least partially a result of its high vitality in the GPEC rates.

Electrodiagnostics of trees.

Most of the physical and chemical properties of all atoms and molecules derive from their electrical charges. Chemical reactions between molecules, for example, or the absorption of mineral nutrients by a living cell are governed by the laws of electricity. Hence the measurable electrical activity of an organism can indicate its state of vitality. Long before visible symptoms of illness occur on the outside there will be an irregularity in the electrical currents.

The method of electrodiagnostics of trees uses the existence and the laws of electrical currents and the tension voltage between the soil and the tree. The GPEC are present in all tree parts, above and below ground. Vladimir Rajda’s method of electrodiagnostics uses a mobile measuring device for direct current (DC), and two special metallic probes. One probe is inserted 20-60 cm deep into the ground at a distance of 0,2 to 40 m from the tree; the other probe is much shorter (c 10 cm) since it only has to penetrate the cambium and phloem layers beneath the bark (the xylem has only 65% of the strength of the currents of the cambium and phloem). Measurements take place at the base of the trunk because here the currents are strongest. They decrease with height and at 6m above ground are only half as strong as just above ground level.

The strength of the GPEC mirrors the vitality of the tree, and a decrease in the electrical activity is inevitably followed by a decrease of water uptake and therefore nutrient supply. This causes the electrical currents to decrease further, while the electrical resistance of the tree grows exponentially (from 30-50 Ohm in a healthy tree to 30.000 – 60.000 Ohm in a severely ill tree). The balance of the nutrient distribution collapses, and after a phase of malnutrition the tree is too weak to ward off parasites and pests. The close relation between the bioelectrical and biochemical metabolism of plants has enabled Rajda to develop an early warning system for forestry commissions, detecting unhealthy trees before physical symptoms appear.

Furthermore, Rajda’s studies have shown that an increase of light raises the GPEC, as does an increase in air temperature (1 degree Celsius equals a change of 2,8 micro-Ampere in electrical intensity). Results of earlier American studies (by H.S.Burr between 1943 and 1966) could confirm, allowing for the above variables plus differing soil and water conditions, that each tree species has its own distinct characteristics in the GPEC, characteristics that are identical for every specimen regardless of elevation or geographical location. Within the limits specific for the species, the GPEC of each tree follow two patterns: during the juvenile stage a continuous rise of GPEC activity with increasing trunk diameter, and throughout its entire life an annual rhythm, with a peak in summer and a low point at midwinter.