Ohio River Pools 1, 2, and 3 Botany Report

Professor Susan Kalisz | Jessica Dunn
University of Pittsburgh, Department of Biological Sciences

In 2003, Pools 1, 2, 3 and part of the Ohio River were the focus of the data collection effort. The length of the river studies were divided into one-tenth of a mile segments. Sampling locations were located through a hand-held GPS unit. As in 2001, we focused on determining the presence and relative abundance of the woody vegetation because they are diagnostic of plant community types. When present, emergent woody and herbaceous aquatic vegetation was also recorded. Our primary survey method of the riverbank woody vegetation involved scanning the riverbank from the 3R2N vessel. We surveyed all woody vegetation from the shoreline to approximately twenty feet back from the river edge. As in the last three year’s studies, additional data on non-woody species was collected for a small number of species or plant functional groups. Three of these plants, Justicia Americana, Iris psuedacorus, and Lythrum salicaria, were mapped and geo-referenced. These herbaceous plants are useful indicator species, plants of special concern or invasive. This baseline data can be used to monitor spread or decline of these species in the future. Justicia americana (water willow) is a native aquatic species found along edges of lakes, ponds, and streams. It usually indicates a healthy and intact riparian zone and is the dominant member of the Waterwillow - Smartweed Community. Iris pseudacorus (yellow iris) is an introduced species also found along edges of lakes, ponds, and streams. I. pseudacorus was often found growing near acid mine drainage in the Monogahela pools studied in 2001. Lythrum salicaria (purple loose-strife) is a highly invasive species that was introduced to the United States from
Europe. Here it is co-occuring with the native floodplain species Lobelia cardinalis (cardinal flower). It is found in scattered areas along our Pittsburgh Rivers and can be closely monitored for spread using this geo-referenced system.

Conclusions

• Four native woody plant communities and one native herbaceous plant community typical of large rivers in North America are found along the Monongahela River, Allegheny Rivers, and Ohio River.
• Although the same communities can be found along the Monongahela and Allegheny Rivers, the two rivers differ in which native communities are most common.
• Including Japanese knotweed, introduced species comprise 17-18% of woody plants along all three rivers. However, a lower proportion of those are both introduced and invasive.
• The frequency of invasive species decreases with distance from Point State Park on both the Allegheny and Monongahela Rivers, suggesting that human disturbance may be facilitating invasion or maintenance of invasive species once introduced.