The understory tree species, Ostrya virginiana (eastern hophornbeam): A “poster child” for shifting forest composition at the prairie-forest boundary in the central United States
Temperate, deciduous forests in the eastern and mid-western United States have been fundamentally changed by human impact in past centuries. Massive deforestation has been followed by a period of regrowth but many studies suggest that the recovering forest is fundamentally different from the pre-settlement forest in composition and function. We investigated forest composition change in the central Missouri River valley in eastern Nebraska and western Iowa, using a combination of current forest plot data and historical accounts.
Our results suggest a marked change in species composition over the past century, with a shade-tolerant, understory species (Ostrya virginiana) dramatically increasing in abundance in these forests to the point where individuals of this species comprise 75% of stands. Also, we find evidence to suggest that oaks and hickories, formerly dominant, overstory trees in these forests, have declined in importance over the past century. Our results are consistent with theories that modern forest environments (highly fragmented, in recovery from clearing, experiencing high levels of deer herbivory and nitrogen inputs, and no longer experiencing fire) have fundamentally altered ecological processes that in turn, have wrought permanent change in the composition and structure of these ecosystems.