Human Ecology: Part 3 (humans coming soon!)

So let’s go back to our “natural” forest and our Circle of Life and all. Quick chemistry review: carbon is The Building Block of Life, plants absorb it from the air and everything else gets their daily intake from either eating plants or eating things that eat plants. But we’re not pure carbon: among other things, living creatures also need small amounts of various minerals like magnesium, potassium, iron, phosphorous, etc, and these are found in the soil, and enter circulation in the food web via plants.

Before humans came along, the movement of these minerals was neither fast nor dramatic. If a beech tree absorbed a molecule of iron from the soil, that molecule might move, say, thirty feet in its path from soil to leaf and back to soil. The biggest exodus of minerals from the system was through runoff, when rain carried them downstream and away to the oceans. To some extent those minerals would be replaced in the ecosystem before they were sorely missed: at their source, from the slow dissolution of rocks in the soil. But overall, this all happened fairly slowly.

Now consider big animals: salmon, deer, migrating birds. Animals, among other things, are self-propelling packets of nutrition (see: hunting.) While carnivores derive direct benefit from animal flesh (nom nom nom), the greater ecosystem feels effects of their movement, too. Bird and bat droppings create phosphorus rich deposits where they roost; I’m sure North America’s buffalo and passenger pigeons had hefty impacts on the areas where they lived; and salmon bring nutrients from the ocean back upstream when they go to spawn. I don’t know about the other systems, but my understanding is that the salmon runs in particular are a rich source of nutrients that the upstream ecosystems have come to depend on.

My glitter frog lives, but won’t eat anything I give it. Harumph.