Green ash, box elder and American elm seedlings are shade tolerant, and as years pass will replace the aging cottonwoods. Bur oak is less common on the lower floodplain, but it is well represented on some of the oldest terraces and common in many ravines leading to the river. The vegetation of these forests varies between the open canopy of cottonwoods compared to the more closed canopy of elm and ash. Common shrubs and woody vines of elm and ash forests include buckbrush, poison ivy, chokecherry, Juneberry, woodbine and wild grape. Buffaloberry, red osier dogwood and Wood's rose occur in cottonwood forests.
Some species show a preference for a particular forest type.
Field horsetails and wild licorice are common in cottonwood stands while you are liable to find Virginia wildrye, sedges, bedstraw and other species in stands of green ash and American elm. The diversity of wildlife species which inhabit the park will amaze and delight visitors of all ages. The park and nature preserve are home to a wide variety of animal life, and with patience and a keen eye hikers will be rewarded with sightings of deer, wild turkeys, hawks, an occasional bobcat, or, at certain times of the year, a bald eagle. A comprehensive list of bird species can be found on the Cross Ranch Bird Checklist, which is also available in printed format by contacting the park. The river sandbars provide habitat for Canada geese migrating whooping cranes and nesting for the least tern.