WSP05273 - Laserfiche WebLink

Home Browse Search

001716 The use of herbicides shows considerable promise in removal of mature stands, but it is more likely that herbicides will best be used to maintain areas already cleared of phreatophytes by some other means. Until fairly recently, stands of tamarisk were held to have no economic value. Now their values for wildlife have been recognized and stressed by some conservationists. In the Gila River area west of Phoenix, white-winged and mourning doves nest in the tamarisk to produce thou- sands of doves (Shaw, 1961). This area provides some of the best dove hunting in the West. What compromise can be made between clearing of the tamarisk for water salvage and flood control, and leaving enough of the groves to provide a reasonable number of doves? Moist Flood Plains Management of flood-plain lands depends upon location of the water table. Where the water table is close enough to the surface to produce conditions favorable for other plants, the management is relatively easy. If the water table is within 4 feet of the surface, the area can be sown to grass or allowed to develop a stand of Bermudagrass or saltgrass. This type of an area--for example, the Rio Grande north of El Paso can be maintained in grass and leased for grazing. Mowing with a rotary mower is most effective in keeping tamarisk and other shrubs from developing a new stand. Grazing also is effective in reducing the return of woody phreatophytes. Evaporation from the soil surface and transpiration by the herbaceous cover will still utilize considerable water, but the use of the land for grazing and the main- tenance of open-flood channels will tend to produce a favorable cost-benefit ratio. Dry Flood Plains Tamarisk-dominated flood plains, with a water table below 4 feet, pre- sent a more serious problem. The tamarisk can be removed, but the establishment of replacement vegetation is difficult; comparatively little is known about what species can be used to replace tamarisk satisfactorily in such areas as New Mexico and Arizona where the rainfall during the growing season is very low. Where the cl.eared lands can be farmed and irrigation water diverted, there is no problem of land management. But in areas where phreatophytes have been removed and irrigation is impossible, clearing may invite serious wind erosion by developing sources of dust. Research is being carried on to develop strains of grasses that can be sown to increase the use of the land after removal of the tamarisk. Water salvage is potentially high in areas with the deeper water tables, because the large amount of water otherwise extracted by deep-rooted shrubs is retained after clearing, and the rate of evaporation is low. 3