 Much of the ecology of the watershed has been affected by <unk> and forestry , and is considered to be in a seral phase . The river travels through several different vegetation zones . In its upper reaches , the Adams flows through the Interior Cedar Hemlock zone . These forests are similar to the coastal forests of British Columbia and contain old @-@ growth trees up to 1000 years in age . Old @-@ growth stands along the river also contain rare species of <unk> , likely isolated by the last Ice Age . The floodplain of the Upper Adams contains wetland species of deciduous trees such as black cottonwood as well as a dense layer of shrubs including black <unk> , red @-@ <unk> <unk> , and <unk> . The lower river is dominated by the drier Interior Douglas Fir vegetation zone . Other conifer species present are Ponderosa pine , Engelmann spruce , and alpine fir . The area around the river mouth has been altered by human activities such as farming and livestock grazing . 
