Ecologically, park uplands are dominated by montane coniferous forest, foothills shrub and grassland communities. Nearly barren rock outcrops and cliffs support lichen and moss communities. Ponderosa pine, Douglas-fir, Rocky Mountain juniper and aspen are the dominant forest trees. Forest understory species include common juniper, Oregon-grape, kinnikinnik, penstemon, arnica mountain muhly, Arizona fescue and Parry oatgrass. Shrublands occupy drier slopes and openings within the montane coniferous forest community. Mountain mahogany, bitterbrush, serviceberry, ninebark, buckbrush, snowberry, common gooseberry and bitterbrush are the common shrub species.
Grasslands occupy most of the lower park elevations and are dominated by big and little bluestem, prairie sandreed, blue and side-oats grama, needle-and-thread grass, New Mexico needlegrass, Indian ricegrass and purple threeawn. A variety of riparian and wetland communities are present along drainages and on seeps and springs; some drainages support the rare wood lily.
