N RANCHING
atural Resources
Water Robbers Just how much water do junipers use?
By Kim Potts A
S JUNIPERS CONTINUE TO CREEP ACROSS PASTURES IN Texas and Oklahoma, researchers are learning more about the impact this is having not just
on forage production but also on water distribution, including storage, runoff and groundwater. Obtaining an accurate measure on juniper water
usage is diffi cult since it varies by number of juniper, size of juniper, location of juniper, terrain, temperature and most importantly the rainfall amount. There’s been some research on how much water ju-
nipers, such as Eastern red cedar, use and the estimate was 30 gallons per day. That number may be too high based on new data. On average red cedar trees used about 6 gallons
of water per day, according to research by Rod Will and Chris Zou, Oklahoma State University professors at the department of natural resource ecology and management. Water usage varies widely for the reasons mentioned
earlier. To illustrate that variation, OSU’s research indi- cates that a 12-inch diameter tree used a maximum of 42 gallons on a day with high temperature and ample soil moisture, but only 1 gallon on a day during a dry period in winter. In contrast, a 2-inch diameter tree used a maximum
of 7 gallons per day and a minimum of 0.2 gallons per day. So just how can farmers and ranchers know how
much water is being used or diverted by red cedar in specifi c area? While there is no straight answer due to so many variables, says Zou, it is safe to say that in- creases in juniper trees in rangeland will not improve surface runoff to streams and ponds. When red cedar is present, you know that water
distribution is impacted due to the competition effect these undesirable plants have on grass and forage production. Early intervention is the best approach to control-
ling juniper populations. “The window of opportunities or options for effec-
tively removing junipers becomes narrow as junipers grow bigger or denser,” says Zou. “Earlier is better, es- pecially when prescribed fi re is an available option.”
52 The Cattleman May 2014
Oklahoma State University and the U.S. Geological Survey’s Oklahoma
Water Science Center are conducting a fi eld-based, multiple-year collaborative research project to understand the effects of red cedar en- croachment.
Some of the implications:
1. Act early — while the effects of red cedar on watershed water budgets are likely to be large when tree canopy cover is high, treating sites with severe infestation is economically impractical.
2. Not all regions will respond equally to red cedar encroachment and red cedar removal. Although streamfl ow might increase more following red cedar removal in eastern Okla- homa, a small increase in streamfl ow in west- ern Oklahoma could be equally important both economically and environmentally.
3. Research has shown the linkage between removal of woody plants and increased wa- ter yield is stronger where water can move rapidly through the soil or parent materials to recharge springs or shallow aquifers.
4. If increased streamfl ow and groundwater re- charge are a management objective, removal should be focused on those sites that have the greatest potential to increase streamfl ow and groundwater recharge.
The removal activities must also cover an area large enough to produce a “useable” increase in stream- fl ow and groundwater recharge. In addition to the potential magnitude of increase in streamfl ow and groundwater recharge, the local water demand, ecological and economic assessments are critical for consideration to prioritize management plans.
thecattlemanmagazine.com
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