Well, I hate to say it but my brain has once again wandered to one of those wacky places it likes to go. This time it was Philippe's fault who had me pondering his post about self organization in vivaria as I drove from the parking lot at work the other day. What is it that makes our landscapes inside those glass boxes speak to our souls and draw our minds into their realm? Why does one container simply look like a box of plants while another of equal dimensions beckons for closer inspection and draws us in as if we have discovered a hidden trail through an enchanted woodland? Well, I am a landscape ecologist and I make no apologies for borrowing heavily from this noblest of sciences when searching for answers. I believe the answer can be found in patches, spawn of a fractal world.

You see, landscape ecology is a study in patches. Landscapes are viewed as a configuration of patches. Within the big patches are smaller patches and within the smaller patches still smaller ones, etc. etc.. For example, a landscape may consist of patches of forests, grasslands, and croplands. Within a forest patch may be many more types of patches - recently burned, bark beetle infested, light gaps from wind throw, etc. The rules that govern where patches occur are complex (remember those fractals?). Some elements (patches) in a landscape are random, or at least create a random, or somewhat uniform, pattern. Others are not random at all.

Does this have ANYTHING to do with vivarium design? I think so. Let's consider a forest in more detail but if deserts are your thing, you can go with that, I'm sticking with forests. What's the first thing you notice when you enter a forest. Duh, it's the trees. More importantly, the mature trees are somewhat randomly distributed. There are also saplings and a scattering of plants on the forest floor, also randomly distributed. These somewhat random elements form the matrix that we call a forest. However, upon closer inspection the forest reveals its true complexity. You might notice that moss tends to grow higher on one side of the tree trunks than the other. Perhaps one side is constantly shaded and therefore retains more moisture. You may also notice a decaying log with a dense growth of many plants growing along its spine, nurtured by the rich humus formed as the log decomposes. In fact, you begin to notice many other patches of high density and diversity of plant growth. Ahead is a tree with exposed roots that form a pocket where leaves collect. Over the years these leaves have produced a deep pocket of rich organic soil where many plants are fighting and thriving. Down the hill is a group of large boulders that form a miniature cliff. At the base of this cliff, sheltered from the wind and nourished by the moisture that trickles down its face, grows a cluster of half a dozen fern species too fragile to survive in more exposed areas of the forest. And at the bottom of the hill is a shallow Y-shaped valley formed at the nexus of three hills. These hills create a swirling eddy where windborne seeds drop out in greater numbers than in other places. This creates a patch with a greater variety of plant types than other areas of the forest. In fact, there are patches everywhere ranging in size from fists to football fields and creating a fantastic number of shapes and textures. These patches are the difference between viewing a forest on a postcard and being there. They allow the eye to wander sending signals to the brain that creates an experience like no postcard can. You are free to shift your gaze between the forests overstory grandeur and its most intimate details while your brain compiles this information into a single experience that envelops you. You are no longer merely a spectator, but a participant of the forest ecosystem. Without the patchiness, a forest is still pleasing to the eye but much less interesting. As with the forest, patches within our glass creations can make the difference between a box of plants and a siren's call for a deeper experience.

However, like Philippe said, vivaria have a tendency to self organize when left on their own so how can we influence whether this organization will become patchy, or random? We do this by taking lessons from nature. You notice in our little virtual trip through the forest that there was a process responsible for every pattern observed. For me, part of the design process is imagining what types of natural process could create little patches in my vivarium and then trying to simulate these patches. The goal is to create heterogeneity at the basic design level of the vivarium. For typically sized vivaria, this means heterogeneity of substrates. For larger designs, it could include other things like temperature and moisture gradients. The idea behind creating the heterogeneity is to create a variety of habitats for plants. This actually requires a reverse in traditional thinking. In vivarium design, it is common to spend considerable effort creating favorable conditions for a wide variety of plants. To insure the creation and maintenance of patches, you should actually strive to create UNfavorable conditions for some plants in one location and unfavorable conditions for different plants in another. You want to avoid including plant species that can grow equally well in all microenvironments created within a vivarium. If you are successful, you will create an environment where different assemblages of plants are restricted to different areas of a vivarium and the location and relationship of these patches will appear natural because they are based on natural processes. However, you should also be conscious of scale. Attempting to slice a vivarium into a large number of patches in hopes of increasing diversity may be a mistake. You could easily end up with patches too small to support the plants they were intended for. You also need to remain aware of the animal inhabitants and make sure patch sizes are adequate to meet their needs. In fact, for very small vivaria, the most suitable design may be a single patch. Our human brains seem to be able to account for scale and a very small vivaria with a single plant species and patch type is interesting and aesthetic while a larger vivarium with a single plant species may become monotonous. In the end, success is measured in the eye of the beholder.

One final thought on the subject is the influence of pattern on process. Just as processes create patterns in a landscape, the patterns can also influence process. For example, it's difficult to have a landscape influenced by fire (a process) if the landscape (the pattern) doesn't include enough fuel to burn (i.e.. a desert). I can think of at least one example where this can be a useful concept in the vivarium. How many of us have purchase a small new plant and placed it in what should have been ideal conditions only to have it die? Ever notice that it is much easier to get larger plants established than very small ones? In many instances this may be a case of pattern influencing process. Even in a vivarium, small plants may be subjected to wide fluctuations in conditions like drying out between mistings where a larger plant doesn't suffer as much. The larger plant may be creating its own microclimate by trapping more moisture in its root ball and creating a dome of higher humidity due to its greater leaf mass. With small plants it may be possible to improve success by clustering plants together to form a patch. These can be small plants of different species. Although they will eventually compete with one another, clustering them to enlarge the patch size may allow them to mutually benefit one another by creating a microclimate that reduces fluctuating conditions. Once established, they can duke it out and self organize to form a very natural looking landscape.

Okay, I'm definitely in rambling mode so I will stop.