Law of Tolerance | reedorganic

Shelford's Law of Tolerance

Shelford's Law of Tolerance is probably the more accurate reflection of natural complexity. It holds that first the presence and then the success of an organism (plant/animal) depends on the completeness and complexity of conditions. The absence or failure of an organism, then, is a function of qualitative or quantitative deficiency or excess with respect to any one of several factors approaching that organism's limit of tolerance for it. An example of tolerence in nature can be found in a wolf pack, too many or too few and the pack fails.

More precisely, each organism--whether the individual or the species population--is subject to an ecological minimum, maximum, and optimum range for any specific environmental factor. Significantly, if all known factors are apparently within their respective ranges for the subject organism and yet it fails, it is necessary to consider additional factors or a more complete array of interrelationships, including interactions with other organisms.

When faced with any such situation, it is essential to study both the intact ecosystem accompanied by experimental laboratory work. By isolating organisms from their populations and communities, field biologists will have a better awareness of the ecological reality associated with the processes they are investigating.

There are significant corollaries to the Law of Tolerance. An organism may have a wide range of tolerance for one factor but a narrow range for another. Logic suggests that organisms with wide ranges of tolerance for many, if not all, factors will be the most widely distributed. Within an organism or species, when conditions are non-optimum for one factor, limits of tolerance for others may be narrowed.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

During his research in the early 1900's, Victor E. Shelford may not have understood just how profound his concept of the Law of Tolerance actualy was. The study of microbes in the soil, water and on plants was at best, in it's infancy. Scientist now understand without microbes, the earth would just be another rock floating through space. Today biobased technology is studying the interrelationships between the different strains of microbes and the symbiotic relationship created between the soil and the plant. In nature, chemicals create the largest imbalances found in the soil, water and air. Whether those chemicals have been "applied" or have been introduced by accident. I am convinced that "Biobased" products will eventually replace chemicals in farming because biobased products are naturally "remediated" and cleaned up by nature itself. And, without any of the harmful side effects known to be caused by chemicals.