The loss of a few charismatic species, where most popular attention is focused, pales in significance compared to the real threat, which is endangerment of the very process of evolution along a path that includes humans. Whether conserving biological diversity is regarded as an ethical responsibility, a ecological necessity, or just another legal requirement, we need systems to measure biological diversity and detect whether change is occurring. In other words, biological diversity must be addressed by inventory and monitoring procedures that are both practical and effective in telling us what we really need to know. That sounds simple enough, but it is a challenge that eludes ecologists and natural resource managers alike. Let's look at the reasons for the difficulty.
Biological diversity is so much more than a head count of species.
It's useful to think of biological diversity not as an attribute, but rather as the very fabric of ecological systems. The species that make up this fabric are interwoven in complex ways that give integrity, strength, and beauty to the whole. It is a complex, resilient, and self-regulating entity that equals far more than the sum of its component parts. The tapestry analogy helps illustrate why biological diversity defies characterization by a straightforward inventory process. The important thing about a tapestry is not the total number of threads, nor even that you have many different colors of threads.