Arizonensis --> Sonoran Desert Naturalist --> Urban Habitats --> Backyard Naturalist --> Compost Heap
Biodiversity in my small backyard reaches its peak in the compost heap. The reason is simple: there is an abundance of ready food resources. True, the biomass of either the Blue Palo Verde tree or the Western Soapberry far exceeds that of the heap, but the trees' biomass is protected by virtue of being alive and defended. The dead leaves, twigs, and vegetable scraps from my kitchen on the other hand are available for immediate recycling.
Like any ecosystem, the compost heap is a dynamic system where primary resources (The producers, living plants, are themselves physically outside of the system.) are competed for by primary consumers, which are in turn the food source for grazers, which then are used as food by predators every bit as ferocious as those on the Serengeti. Even the predators themselves have predators. With so much life, there is abundant death. Organism die and those that thrive continue to produce yet more waste (feces) to be recycled further. Energy contained in the starting material is expended and vital nutrients such as nitrogen and phosphorous are cycled from organism to organism. The net result of all this activity is the conversion of dead plant material into a rich humus.
My heap system is a simple one: leaves, pruning waste, cucumber peels, radish tops, etc. are placed on the top of the heap. A white board is used as a cover to keep some of the direct sunlight off and to help hold in some of the moisture. As the various molds, insects, earthworms (Eisenia foetida) and bacteria degrade my offerings, the volume decreases so that my heap maintains a constant height even as new material is added almost daily. The balance of materials added helps to keep down odors, breeding of house flies, and the attraction of larger scavengers (i.e. I don't want cockroaches, rats or dogs!). High energy food waste such as meat scraps, potato peels and whole fruits is not entered. Because a lot of the compost is largely cellulose (dead leaves and twigs) it is necessary to add some green wastes that have nitrogen and phosphorous. These nutrients improve the efficiency of molds and bacteria in breaking down the cellulose; without them the heap would tend to grow rather than stay constant. There is a desirable balance between nutrients, energy and cellulose.
Inhabitants of the Compost
The insects, mites, spiders, crustaceans, centipedes, fungi, actinomycetes and bacteria common in the compost heap are also commonly encountered in naturally occurring compost such as leaf piles or beneath rich soil. They are simply more abundant in my augmented system.
Copyright Michael J. Plagens, 1999-2011