 As the landscape rises , trees become smaller and more sparse , with stands broken by areas of exposed granite . These include lodgepole pine , whitebark pine , and mountain hemlock that , at highest elevations , give way to vast expanses of granite as treeline is reached . The climate in these habitats is harsh and the growing season is short , but species such as pika , yellow @-@ bellied marmot , white @-@ tailed jackrabbit , Clark 's nutcracker , and black rosy finch are adapted to these conditions . Also , the treeless alpine habitats are the areas favored by Sierra Nevada bighorn sheep . This species , however , is now found in the Yosemite area only around Tioga Pass , where a small , reintroduced population exists . 
