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<br />Preface <br /> <br />In the not too distant past, lower Rincon Creek (a portion of a small stream in <br />the Sonoran Desert) was dominated by a riparian forest that in some areas <br />extended more than half a kilometer from each side of the stream channel. The <br />predominant woody vegetation was Arizona walnut (fuglans major), with <br />some of the larger individuals exceeding 5 m in circumference and towering <br />close to 20 m above the floodplain. During this time, groundwater levels <br />probably never dropped more than a few meters below the soil surface, and <br />streamflow was nearly perennial. The well-being of a plethora of wildlife spe- <br />cies depended on this riparian area. Water-loving species like the beaver (Cas- <br />tor canadensis) and the southwestern Woodhouse toad (Bufo woodhousei <br />australis) lived year-round in or very near this ecosystem. The mountain lion <br />(Felis conca lor), coati (Nasua nasua), mule deer (Odocoileus hemionus), <br />Yuma myotis (Myotis yumanensis), and vermilion flycatcher (Pyrocephalus <br />rubinus) were continual visitors. <br />This riparian ecosystem no longer exists. During the past 60 years, the <br />combined impacts of groundwater pumping, stream channelization, agricul- <br />ture, livestock grazing, and, currently, urbanization have almost completely <br />destroyed this area. Today, streamflow occurs only following heavy rains, and <br />scattered remnants are all that remain of the once immense riparian forest. <br />Unfortunately, the devastation that befell the riparian ecosystem of lower <br />Rincon Creek is not unique. Riparian ecosystems have disappeared at an <br />alarming rate all across northern Mexico and the southwestern United States. <br />Although the extent of damage is still not well understood, most observers will <br />agree that the deterioration of riparian ecosystems in this part of the world has <br />reached significant proportions. <br />This book is designed as a manual for those in the natural resource field <br />who have taken on the task of repairing damaged riparian ecosystems. The <br />emphasis is on evaluating riparian ecosystems so that the causes of ecological <br />deterioration can be understood; restoration based on a sound understand- <br />ing of the causes of decline will have a greater chance of succeeding. This <br />