Submitted to: American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: June 15, 2002
Publication Date: September 9, 2002
Citation: RANGO, A., HERRICK, J.E., GIBBENS, R.P., MORAN, M.S. RECONSIDERATION OF USING WATER PONDING DIKES TO REESTABLISH NATIVE GRASSES IN SHRUB-INVADED AREAS OF THE SOUTHWEST. AMERICAN GEOPHYSICAL UNION, CHAPMAN CONFERENCE ON ECO-HYDROLOGY OF SEMIARID LANDSCAPES: INTERACTIONS AND PROCESSES. 2002. ABSTRACT P. 33. Technical Abstract: Many rangeland treatments have been tested to cause a reversal in the process of shrub invasion into desert grasslands. It seems that, because of the harsh nature of the arid environment, just removing shrubs and even subsequent seeding with native or introduced grasses is not enough to reverse the trend. Several examples are illustrated with historic aerial photography. A more integrated approach seems to be necessary and particularly one that involves concentrating water to increase localized soil moisture. Increased soil moisture alone is not always enough as is evidenced by historic treatments where brush water spreaders and contour terraces were used, although the results of these treatments may have been different if the original treatments had been properly maintained. The relatively simple construction of water ponding dikes seems to produce the best result, and the success and persistence of the dikes appears to vary with soil type. Inexpensive to construct, these dikes require little maintenance but have produced significant results over a period of years. The vegetation response of the Jornada dikes is easily seen using air photos, and the vegetation pattern produced is very similar to naturally occurring "banded vegetation." Grass response has been positive in all water-ponding dike installations, and it appears that native species in the local seedbank respond better than introduced species. Well planned installation of these simple structures over a landscape unit may initiate changes that could lead to reestablishment of grass in the desert ecosystem. Study of banded vegetation systems may generate guidelines for dike spacing on soils with similar hydrologic properties. A series of research water ponding dikes will be established in New Mexico and Arizona to test this treatment over larger areas of the Southwest.