PS 82-73 - Dendrochronology as an assessment tool of tree growth in wetland restoration projects

Friday, August 7, 2009
Exhibit Hall NE & SE, Albuquerque Convention Center
Matthew R. Opdyke , Natural Sciences and Engineering Technology, Point Park University, Pittsburgh, PA
Joshua D. Kuikahi , Natural Sciences and Engineering Technology, Point Park University, Pittsburgh, PA
Background/Question/Methods

Riparian wetland restoration of disturbed landscapes is essential to ensure the sustainable health of watersheds. Wetlands provide vital habitat and food for a variety of wildlife as well as serve an important function in filtering overland runoff. This study measured the diversity of wetland plants in a 20-acre riparian wetland, which was previously a golf course between 1968 and 1983, and introduces the application of dendrochronology as a potential tool to investigate the impact of climate, hydrology and historical land use on tree growth. Wetland plants were surveyed in late spring and early fall at ten plots randomly located throughout the wetland. Herbaceous vegetation was identified within a 1 m2 subplot and saplings within a 10 m2 subplot at each plot. Two increment cores per mature tree were collected from the riparian wetland and along the wetland boundary for tree ring analyses. For each tree, significant changes from the average background tree ring width were compared against temperature, precipitation and land use practices to assess the cause of impact to tree growth.  

Results/Conclusions

Wetland plant surveys identified grasses and sedges as the dominant herbs, box elder (Acer negundo) and American elm (Ulmus Americana) as the dominant saplings and American sycamore (Platanus occidentalis) and eastern white pine (Pinus strobus) as the dominant mature trees. Tree ring analyses determined that the mature trees are approximately 51 years old. The two sycamore trees show a 138 and 21% increase in tree ring width between 1998-2002 and the average background tree ring width from 1992-2008. This data suggests that at the turn of the century, climate and hydrology conditions were ideal for the sycamores, which thrive in wetland habitats. The tree ring widths of the white pine averaged 7.5 mm between 1960 and 1965, steadily decreasing to an average of 0.6 mm between 1985 and 2008. The preferred habitat of white pines are uplands, thus, our tree ring analyses support inhibited growth of white pines planted in a wetland. Dendrochronology can be a useful tool in assessing historic tree growth among a variety of species in a wetland to determine which trees are best adapted to a wet environment. This information can provide guidance to wetland managers during the restoration planning stages of wooded, riparian wetlands.

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