Lichens in Forest Park and Nitrogenous Air Pollution

Lichens have been shown to be useful bioindicators for determining levels of nitrogen deposition related to air pollution. Preliminary lichen surveys in Forest Park in 2011 and 2012 revealed the presence of lichen species associated with high levels of nitrogenous pollution. The summer of 2013, we conducted lichen surveys at 25 permanent research sites that had been set up in Forest Park and the Ancient Forest Preserve in 1993. The majority of the lichens we collected at every site were classified as indicative of worst, poor, or fair air quality, with few lichens found that would indicate good or best air quality. Lobaria is a lichen common in Oregon and is important in the normal nitrogen cycle in forests. However, Lobaria is very sensitive to nitrogenous air pollution and is associated with the best air quality category. We only collected Lobaria at one site in the middle of the park. We found no significant differences in lichens in the different air quality variables in the various sections of the park, indicating that all of Forest Park is subjected to poor air quality

Twenty Years of Change in the Tree Community in Forest Park

In 1993, 24 permanent sites were randomly located in Forest Park with one additional site in the Ancient Forest Preserve. Three 250-meter-square quadrats were randomly located at each site. All trees within each quadrat were identified to species, and the dbh (diameter at breast height) of each tree was measured. Saplings were members of tree species less than 10 cm in diameter and saplings were members of tree species that were less than 2 meters in height; basal diameter was measured for saplings. Data were initially collected in 1993. Measurements were repeated in 2003 and 2013 at the same locations using the same methods. We found significantly fewer live trees and live saplings (treesdbh) in each decade, although the rate of tree mortality appears to be slowing. When examined by section of the park (city, middle, far, old growth), the far section had significantly more live trees and saplings than did the city section, but there were significantly fewer live trees in all sections of Forest Park in 2013 as compared to 1993. Our findings suggest important implications for management of the park

Air Pollution: The Trees Aren\u27t Lichen It

The Keck Summer Collaborative Research Program provides opportunities for Linfield College students and faculty to conduct research on issues related to the Pacific Northwest, and to bring the research findings back into the classroom within the subsequent academic year. Students partner with faculty to conduct research and present their work to other students, Linfield staff and faculty, and community members during a series of brown bag lunches. Wes Hanson, Leigh Hanson, Meghan Lockwood, and Morgan Yarber conducted research with Nancy Broshot and gave this presentation during the summer of 2013