Ecosystems, Soil Exhaustion and Soil Toxins

Show Summary - March 16, 2009

Guest: Tom Atzet

Tom Atzet, PhD (Merlin, OR), Regional Ecologist, U.S. Forest Service (Retired). "Soil Exhaustion, Carrying Capacity and Toxic Buildup"

Tom Atzet, Forest Service Regional Ecologist for southwest Oregon, now retired, dropped by again to talk about the impact of humans on natural ecosystems.

There was some discussion that water, as important as it is to life, is omitted from the U.S. government's "official" nutrition chart. Tom suggested that water may be simply "too basic," like air, and that it therefore has always been assumed as a "given." Lately, of course, drinkable water and breathable air are no longer "given."

Tom talked about the limits of a species in the ecosystem, which is called "carrying capacity." Carrying capacity is usually "density dependent," which means that if the population exceeds the carrying capacity (or grows too dense), the environment will "beat it back" through starvation, predation, disease, lower birth rate or lower infant survival.

It is important that humans understand this and learn to live within the Earth's processes. We must live the way the Earth wants, says Sharon, with no extremes.

Human carrying capacity is a major scientific issue right now.

There was also extensive discussion of soils, which Tom described as "like a bank." Soil starts out as pulverized rock, to which are added free minerals, water, solar energy, decayed organic material and microorganisms. This builds up the bank and creates a life-sustaining reservoir.

Soils are highly variable. In southwest Oregon, as fertile as it is, there are large areas of "serpentine" soils that are toxic to most plants and where only a few highly adapted species grow. There are also highly adapted species that will grow in the drifting desert sands of Arabia and North Africa but these areas are, by and large, extremely infertile. In contrast, the Nile Delta is extremely fertile, mainly due to annual flooding.

In the distant past, people tended to live within the parameters of nature and when an area became depleted or exhausted, they moved away for a few years while it healed.

Tom pointed out that the oceans have long been a dumping ground for human waste and that this has affected fisheries, coral growth, marine food chains and other marine life. This, according to Tom, has nothing to do with carrying capacity - rather, it is an assault so severe that ecosystems cannot function at all. It is like covering the land with concrete. You can let it lie fallow for decades and it will not recover.

That's why "dead zones" are beginning to turn up in the oceans - and on the land.

Regarding climate change research, Tom is an outspoken advocate of letting the facts fall where they may. He believes emphatically that it is imperative for scientists to keep personal agendas out of their research and that they must avoid "cherry picking" information to support their agendas. When you have an agenda, in Tom's view, is not science but politics.

Categories: Ecology and the environment; global warming and climate change