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Dr. Susan Kalisz,
University of Pittsburgh Department of Biological Sciences
The conservation and restoration of river systems
is an area of global concern and action (Dynesius and Nilsson 1994).
Riparian zones, the areas of contact between land and water along
streams, rivers, ponds, lakes, and wetlands and the plants that
live in them are key components in river ecosystem stability (Wetzel,
2001 Chapter 10). Riparian plants' root systems help to stabilize
riverbanks and stream banks, reduce erosion and decrease runoff
and therefore significantly decrease the concentration of diverse
nutrients, including nitrogen and phosphorus and other pollutants
entering the river. Riparian plants provide habitat structure, food
for terrestrial organisms and maintain water temperature through
shading. Research in this area indicates the importance of riparian
zones in the health and function of watershed ecosystems (reviewed
in Ward and Tockner, 2001). However, long-standing disturbance of
the river and riverbank creates conditions that both diminish the
local native biodiversity in the plant community and can foster
the invasion of non-native plant species (e.g. Gilvear et al., 2000).
Both of these factors can diminish ecosystem health. Understanding
the structure and composition of plant communities along rivers
in the context of the management (disturbance) milieu is a key first
step in maintaining and/or improving river function and health.
The Botany Team's goal in 3R2N project is to create a large-scale
spatially referenced database of woody vegetation and selected herbaceous
plants. This database will be used to determine the occurrence of
native plant communities and invasive species in the context of
human management of the Three Rivers.
- The data to date from the vegetation
surveys of 2000 and 2001 indicate that the riverbanks house
a diverse assemblage of woody plant species.
- Four woody plant communities and one
herbaceous plant community have been identified.
- Introduced species comprise 15-24% of
the total woody species abundance of the riverbanks. However,
a lower proportion of those are invasive.
- Tree of heaven and Japanese knotweed
are the most invasive species noted to date.
- There are several areas regions of the
riverbank that are worth protecting, especially the remnant
floodplain forests.
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