Biodiversity has become commonly used by conservationists, environmentalists and land management professionals, but what exactly does it mean? Has it fallen into the Humpty-Dumpty trap “...when I use a word it means just what I want it to mean, neither more nor less”?

Biological diversity is a complex topic which is generally taken to mean variability amongst living organisms, but which has three interlocking components – genetic, species and ecosystem.

Genes are the building blocks which determine how an organism develops at the population, species and community levels. It is the raw material for evolution and adaptation, which is why agricultural monocultures with their attendant uniformity are so dangerous. Genetic diversity can be studied satisfactorily only in the laboratory.

Species diversity is the easiest to study since the units which make it up are easily recognized and identified. It can be measured in terms of numbers within a species in a defined area or numbers of species.

The broadest unit of biodiversity is the ecosystem. It describes the plant, animal and invertebrate communities and the interactions and processes amongst them. It could be a small pond, a river catchment, an island or any selected, more-or-less homogenous area.

Once lost, biodiversity can only be recovered slowly, and with difficulty. It can be lost due to a catastrophe or cataclysmic event, as happened to the dinosaurs. Chance arrival or introduction of an aggressive species can result in extirpation or major population reduction in natural residents.

Many of the lay public lack detailed knowledge of biodiversity but they do have legitimate concerns: the risk of possible extinctions, and measures to minimize these risks; damaging commercial exploitation and, again, steps to minimize these consequences.

Despite all the many facets of meaning, biodiversity signifies stability, ability to respond to changes in habitat factors, and a measure of certainty for the future – all welcome and desirable concepts to be guarded jealously.

Dr. Roy Strang writes weekly on the environment for the Peace Arch News. rmstrang@shaw.ca