Natural and Unatural Red Dirt

by Jack Ewing

Because of their small size we tend to underestimate the amount of earth that ants excavate. Yet among Mother Nature's creatures, leaf cutter ants take the prize for earth moving. A researcher once measured the soil that a colony of these ants carried to the surface when constructing their system of chambers and tunnels. Over a period of five years they piled 22 cubic meters of earth -- about two dump truck loads -- on top of their mound. Entrances are built on the sides of the colony in such a manner that water drains away from the openings and doesn't erode the undisturbed soil.

Soil is not the only thing that these amazing insects move around in large quantities. It has been calculated that leaf cutter ants harvest around 15% of the folaige produced by the rainforest. This leaf matter is carried into the underground colony and fed to a fungus which, in turn, is eaten by the ants. All of this organic material is eventually incorporated back into the soil and the nutrients recycled by other life forms.

The leaf cutter queen's death brings on the death of the entire colony. The earth in and around the leaf cutter mound is loose, well aerated and fertile. In a short time a multitude of rainforest species, each struggling for a place in the rich soil, take possession of the former colony. So important is the earth moving activity of the leaf cutter ants that, were the species to perish, the ecology of the rainforest would suffer and biodiversity diminish significantly.

Ants aren't the only excavaters in the animal world. Earth earth worms, ground squirrels, bumble bees, pacas, armadillos and peccaries, to name a few, all alter the structure of the soil. All of these species provide environmental services such as loosening, aerating and fertilizing the soil. Their earth moving activities are beneficial to other living species. I can't think of a single wild species that causes environmental damage by excavating and moving the earth.

For many millenium humans have also altered the face of the earth. We have tilled it, drilled it, mined it and rearranged it to suit our needs. Our machines and domestic animales have compacted the soil. Through out human history our inventions have increased our ability to push, scrape, dig and perforate and have accelerated the pace at which we restructure the planet. Unlike wild earth movers, our activities, seldom if ever, benefit living species other than ourselves. When we move earth the environmental consequences are invariably negative to one degree or another. Notable natural disasters precipitated by our altering of the soil include things such as dust storms, severe erosion, flooding and landslides.

While leveling off a ridge top near Hacienda Barú , a neighbor once pushed many tons of red dirt down a hill without taking any precautions to contain it. Rains washed the soil into the stream at the bottom where the flow carried it seaward, clogging channels, causing flooding and choking out many species that resided in the wetlands near the beach. Today, twelve years later, the downhill neighbors, both human and wild, are still suffering the effects of that ill thought-out project.

hen we wish to build something, it is important to consider what we hope to accomplish and how it can be done with a minimum of earth moving. Architectural alternatives exist that will fit your construction to the lay of the land without scraping out a level house pad. If we must move earth to accomplish our objectives it is important to think carefully about the consequences and prepare anti-erosion measures in advance. Roads can be built with a minimum of erosion. Responsible development requires planning and preparation. Rather than altering the lay of the land to accommodate your construction, modify your design to make it fit the land. Keep it as close to Mother Nature's design as possible and you won't go too far wrong.

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Focussed in Birdwatching Costa Rica and Ecotourism