garden guest: a Black Swallowtail caterpillar
A garden can be thought of as a work of art, a habitat, a food source, a sanctuary, a status symbol, or a bother. There is a big difference between a Zen garden with its carefully placed rocks, raked gravel and tenderly manicured handful of shrubs, and an overgrown backyard with 30 years' worth of accumulated plants fighting for space. An orchid connoisseur certainly has a different approach than a family with a vegetable garden expecting to harvest a significant quantity of food for the effort. There are many factors that are in place before any human even starts to make their mark on the land. Location and size are two that immediately come to mind. Secondary considerations include money and manual labor available, time allotment to both creation and maintenance, and even community regulations on how uniform or individualistic one's garden may be. Given the same space in the same area and assuming equal resources, though, there are still going to be all manner of results.
The most basic garden is that little flower bed that completes the average picture of a typical house, with a green lawn, a tree plus several common shrubs for accent, and a sidewalk to the front door. Of course, you can get even more "basic" than that: a potted flower on the windowsill. While some gardeners lament the fact that plants keep changing (they'd probably be happier with plastic flowers that are guaranteed to always look their "best"), others like to rearrange the elements of a garden so often that it is like a chalkboard - erased regularly to create the next image.
Another way to view a garden is as a small ecosystem, complete with various trophic levels and subject to the tweaks and curiosity of its human handlers. A trophic level refers to the placement of organisms in the food web. Plants comprise the first trophic level because they take energy directly from the sun and convert it into a form that can be used by other organisms. Insects make up a big part of the next level, because they eat plants. Rabbits are there too. Most birds are in the third level because they eat the insects that eat the plants. Some, like hawks, eat the rabbits too! Although these examples seem simple, the whole system is actually quite complex. There are insects that eat other insects. Include parasites, parasitoids (parasites that kill their host), hyperparasites and hyperparasitoids (parasites of parasites), and it really starts to get mind-boggling. After all these permutations, the surviving end-product insect might STILL be eaten by a bird. And when the bird dies, it is eaten by insects!
garden guest: a Black Swallowtail caterpillar |
When watching the escapades of all those animals, it is rather easy to stop thinking of plants as the end result of gardening. The plants provide the stage, but the drama occurs when the cast goes about the everyday challenge of surviving. Perhaps one of the most engaging aspects of animals in the garden is that they move around and come and go much more quickly than plants. Since we are animals, with typically short attention spans, it is at times a bit of an effort to stay interested in something that takes weeks just to grow a few inches and perhaps months to bloom. Of course, the slow time scale of plants is definitely an advantage when it comes to keeping a yard's jungle-like growth under control. In theory, we can move faster than the plants, so we should be able to stay ahead of the vegetation that threatens to overwhelm us, snaking across our sidewalks, climbing up our houses, and hanging over our driveways. Even the weekend gardener can usually feel that they are in control of their plants.
One way that we can easily influence our garden is by choosing what plants live and which die. Most people will remove plants that have sharp spines, poison-filled bristles, or produce a rash on human skin. They will install plants that are attractive to them. Some prefer a yard filled with all manner of different kinds of plants, others want uniform beds of a single color, while others decide what to include by using the surrounding native landscape as inspiration. If one likes butterflies, then it makes sense to have host plants for caterpillars and plenty of nectar sources for the adults. The tricky part comes when it is necessary to learn WHICH plants will fill those requirements. The prettiest flowers don't necessarily produce good nectar, and butterfly caterpillars are very specific about what plants they can eat. Things get even more complicated. Butterflies are closely related to moths. Both start life as caterpillars that eat plants. There are at least 15 times as many moth species as butterflies. Yes, that means that if there are 30 butterfly species visiting a garden, there could easily be over 450 species of moths. That's a lot of caterpillar mouths to feed! Now comes the challenge of encouraging certain caterpillars while discouraging others. The same predators and parasitoids that attack moth larvae can usually do the same to those of butterflies. There is a lot in nature that we cannot control.
It is interesting to notice, as one walks down any typical residential street, just what style of gardening the owners of the different houses prefer. Within the little individual plots, there might be nothing more than grass and privet, or there might be a small forest of trees, or perhaps a riot of colorful blossoms. Some gardens will swarm with butterflies and bees (and thousands of additional unseen insects), while others might have only the occasional squirrel running around. Birds might be nesting, lizards basking and snails creeping about, or there might be nothing moving at all. Besides all the choices gardeners make in what plants they grow, how much time and money they spend, and how conscientiously they prune, fertilize and mulch, they also decide whether or not to use pesticides. It's all a matter of taste.