In order to answer this question, we must understand a few things about habitat. Habitat is often specified by rather general terms like rainforest, saltmarsh or desert. In order to avoid misunderstandings, descriptors such as riparian, upland, woodland, or Sonoran are used. These descriptions leave us with a certain impression, partly based on our own experiences. Often species lists are added. Since there are almost an infinite number of ways of arranging a bunch of components, drawings or photographs might be used, but these too are usually inadequate. (Remember those pictures of the Grand Canyon or the towering rainforest trees you've seen or taken.) To fully convey all aspects of a given habitat, any scheme needs to be very elaborate. Unfortunately, habitats are not static - the components are dynamically related to one another; since that relationship is constantly changing, so is the habitat. In addition, the components are dynamically related to the surrounding region. (It is only recently that we have begun to acknowledge and discuss this dynamism - the economy, pollution, culture, etc. have always been global in nature. We have just been slow to recognize it.) The terms and descriptions indicated above are inadequate to discuss the interaction between the Miss Muffett and the spider. While Miss Muffett does have a global impact, her effect is mainly local. In this case, we need to look at microhabitat. In order to do this, I want to consider an approach which relies on examining those elements that are necessary for any habitat.
For instance, suppose a certain type of spider makes a large web. A large web would require a considerable investment in time and energy. It would need to be strong enough to withstand wind and rain. Even dew on a large web could provide a considerable strain. The supporting substrate would need to be stable enough too so as not to exert undue stress on the web. The best location for such a web might be a large opening in a tree or amidst a group of similar trees. In some areas, these spiders might appear to be specific to one species of tree when in reality, it is the nature of the spaces that the trees provide that is important. Look around you - do all the trees have the same openness? For our purposes, we might regard ``space'' as one of these fundamental elements.
So today's question is ``What elements do you think are basic to any habitat?'' (If you have a problem here, start with one element, perhaps ``space'' as indicated above, and consider the questions which follow. Then determine which elements you need to complete your descriptions - e.g. color, texture, fire.) Try out your scheme, perhaps in your home or garden. How does the relationship, between the elements you chose, change as you consider smaller areas (i.e. look at your area as a collection of microhabitats - compare them, relate them)? What changes take place over time? How do you contribute? What about your friends or not-so friends? In the next article we will look at how Miss Muffett might have affected the microhabitat into which the spider entered.
Ron Lyons (volunteer 1990-1999)