SHIGOMETRY Cambium Electrical Resistance (CER)

First The major problem that has followed the meter since its beginning in 1970 has been the lack of understanding of trees by the operators.

Keyword Definitions of Terms (Keyword definitions give the most important words that define a term. Complete sentences are not necessary.)

Capacity - What you have as a result of your genetic code; a potential source for some future action or product.

Ability - What you are doing with what you have; a dynamic or kinetic process.

System - A highly ordered connection of parts and processes that have a predetermined end point - product, service.

Stress - A condition where a system, or its parts, begins to operate near the limits for what it was designed.

Strain - Disorder and disruption of a system due to operation beyond the limits of stress.

Vigor - The capacity to resist strain; a genetic factor, a potential force against any threats to survival.

Vitality - The ability to grow under the conditions present; dynamic action.

Health - The ability to resist strain.

Disease - A process that decreases the order and energy of a living system to the point of strain.

Survival - The ability to remain alive or functional under conditions that have the potential to cause strain.

Generating system - New parts and processes form in new spatial positions; plants.

Regenerating system - New parts and processes form in old, or preoccupy, spatial positions; animals.

Wood - A highly ordered connection of living, dying and dead cells that have walls of cellulose, hemicellulose and lignin.

Symplast - The highly ordered connection of living axial and radial parenchyma in wood and bark.

Apoplast - The highly ordered connection of dead cells and cell parts that make up the framework that holds the symplast.

Quality - The characteristics that define a product, service or performance; quality can be low or high



The thicker the cambial zone [CZ] the more vital [V] the tree.  A thin cambial zone [1] will have lower moisture and fewer cations than a thicker zone [2].  When the double needle electrodes of the Shigometer are pushed through the bark [B] and slightly into the wood [W] the pulsed electric current from the meter passes through one needle, through the tree tissues, and back through the other needle to the ohmmeter in the Shigometer where resistance in kilohmís is measured. 


Because the cambial zone is so moist and because it contains high amounts of cations, most of the current flows through this zone.  The higher the electrical resistance, the less vital [V] the tree.  You can develop CER (cambial electrical resistance) records for your major trees in a very short time.  Select 20 trees of a species at random in any area.  Take two readings per tree; 40 readings.  Divide the sum of all readings by 40.  Now you have your CER mean for that species.  To work with many species. first establish their means.  Then use each mean as the denominator for each new reading.  For example with four different species: 5/5,6/6,7/7.8/8 etc. all equal 1; and 10/5. 12/6, 14/7, 16/8. all equal 2.  You then record each new reading as a ratio of its mean.  All trees with a 1 will indicate they are the same as the mean.  All trees with a fraction below 1 will be better than the mean; and all trees with numbers higher than 1 will be worse than the mean.  All of this information can be easily stored in a computer for comparison later.


Trees, like all organisms, die in three basic ways: depletion, dysfunction and disruption.

See "Demons Of D"

Forest Tree, City Tree

Trees became tall, massive and long-living plants as they grew in groups. Trees not only connect with other trees by way of root grafts but also by way of the fungi that are associated with non-woody roots; the organs are called mycorrhizae. Trees also connected with many other organisms, very large to very small, in ways that benefited the trees and their associates. Synergistic associations are important parts of the tree system.


A forest is a system where trees and many associates are connected in ways that ensure survival of all members.


It is important to remember that the genetic codes for survival, or vigor, came from trees growing in forests.


When the forest-coded tree is brought into the city, the factors that affect vitality become extremely important. The architecture of most city trees as they grow as individuals is different from most of their relatives in the forest where trees grow in groups. Forest trees have group protection and group defense. The individual tree has neither.

Myth 69.

The Shigometer gives resistance in K ohms.
 The operator must interpret the numbers and their meanings.  The meter is a tool.  And, like any tool, it is only as good as the user.  The meter has been grossly misunderstood and misused by many people who expected the meter to give them an answer.  The meter sends a pulsed electric current and with a variety of probes or electrodes, the resistance of the current is measured in kilohms or thousands of ohms.  Once the pattern of measurements for any substrate and its alterations are determined, the meter can rapidly help the operator to understand the condition of other similar substrates.  The major problem that has followed the meter since its beginning in 1970 has been the lack of understanding of trees by the operators. (See MODERN ARBORICULTURE pages 367-376)

Many references on the SHIGOMETER can be found listed in rear MODERN ARBORICULTURE.  Remember a common issue is that people often quote sitings and the info the claim is in the document does not exist.  Not to mention most research on diseases are done in a lab on 1 year old saplings.


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