Rain in the Desert: July 6, 2010
At Circle Ranch, Hudspeth County, far-West Texas, we get 11″ average rainfall per year. This is 1/2 the normal rainfall in Laredo where much of our Texas Scaled Quail research has been done. Moreover, West Texas rains, unlike Laredo rains, come mostly in July and August.
South Texas blues have relatively-moist springs: West Texas blues do not. Average also means that in one year out of two, we get less than 11″! Our brittle desert grasslands have evolved under these natural cycles. They will function nicely in spite of low and erratic rainfall if plants are healthy. ‘Low’ rain years are as normal as seasons; these cycles presumably are necessary to the health of the plants and animals, although we may not be able to trace out why this is so.
If we get 11″ at Circle and 80% runs off or evaporates immediately, our effective rainfall is about 2″ per year. On the other hand, if we get only 6″ of rainfall but 2/3 soaks in, our effective rainfall is 4″ per year: double the effective average rainfall on most ranches in our area, even though many would call only 6″ a drought. Allan Savory told me on our first meeting, “Humans cause drought”. I thought this was nuts. Eventually I realized that he meant that when human practices lead to bare ground, malfunctioning water cycles and permanent drought caused by excessive evaporation and runoff are the inevitable result. As you fix the plants, water cycles improve, more grass grows and more grazing is both possible, and necessary to maintain the recovery. Healthier plants, grazed according to a plan that helps quail, means more quail than otherwise possible in wet years or dry years.
One quail study found that: “Precipitation effectiveness (precipitation /evaporation) was two to three times stronger than a habitat index in explaining fall density of bobwhites in southern Texas,” ( Guthery: The Science of Quail Management and the Management of Quail Science, Quails of Texas, p.411).
Whatever our precipitation, how can we make it more effective? Make our plants healthier! Is ‘protection’ from grazing the way to do this? It depends on what is meant by ‘protect’. On brittle desert grasslands, plants and animals are symbiotic after 20 million years of co-evolution. The notion that, in an ecosystem that formed over 20 million years under periodic severe grazing by very large herds, removing the animal impact that only large numbers of grazers can give plants will produce plant health, simply defies common sense. So does the idea that we can burn, poison and bulldoze rangelands back to sustainable health. While grazing applied in the wrong way will kill plants, no grazing, or too little grazing, or any grazing that does not mimic nature, will also, eventually, kill plants.
In our QuailMaster study we visited beautiful ranches across the state. One, on the Canadian River, had a ‘show-off’ pasture that had been rested for eight years. There were many dying grass plants. Dead, blue-black centers that can be pulled right out of plant after plant. Empty hearts in many bunch grasses. Similar damage, the result of partial and total rest, was evident on every ranch we visited. Dying plants lose the root mass that is the sponge which traps and slowly releases rain. Grasslands and savannas shift to woody plants, water cycles become ineffective.
Aldo Leopold studied water cycles at the macro level, but he did not look at them a square yard at a time. As we inventory plants and note plant height, we should also ask if these plants are healthy or dying, if there is a complete community of animals present, about soil life, and if water, minerals and sunlight are effective.
Here is Allan Savory discussing how to make rain more effective: