http://hdl.handle.net/2027.42/49252 http://deepblue.lib.umich.edu/retrieve/183866 http://hdl.handle.net/2027.42/49252 Search the Channel search http://deepblue.lib.umich.edu/simple-search http://hdl.handle.net/2027.42/62030 Title: Factors affecting prey-derived nitrogen in flowers of the purple pitcher plant, Sarracenia purpurea<br/><br/>Authors: Foss-Grant, Andrew P.<br/><br/>Abstract: The Purple Pitcher Plant, Sarracenia purpurea, is a carnivorous plant that lives in low-nitrogen environments such as bogs. This study looked at 50 pitcher plants in Mud Lake Bog, Michigan and used stable nitrogen isotope ratios and environmental and morphological factors to determine levels of prey-derived nitrogen in pitcher plant flowers and the factors that correlated with these nitrogen levels. It was hypothesized that flowering structures would be more reliant on insect-derived nitrogen than the pitchers themselves, and so expected to see an increase in prey-derived nitrogen in flowers. Significantly higher levels of insect-derived nitrogen were found in flowering structures compared to pitchers, with a mean in flowers of 73% prey-derived nitrogen. Pitcher size, color, soil temperature, surrounding biomass, number of flowers, and captured insect biomass all correlated with variation in prey-derived nitrogen values in the flowers. It was concluded that flowering structures preferentially received prey-derived nitrogen over pitchers, and that several environmental and morphological factors combine to affect the percentage of insect-derived nitrogen being used to produce these flowers.<br/><br/>Description: REU http://hdl.handle.net/2027.42/62028 Title: A study of atmosphere-forest exchange of reactive nitrogen via measurements of nitrate in canopy top leaves<br/><br/>Authors: TerAvest, Michaela<br/><br/>Abstract: Nitric acid deposited on leaf surfaces may be an important player in the atmospheric nitrogen balance in the deciduous forest environment near UMBS. Levels of nitrate deposited on leaf surfaces at the top of the canopy were measured at different times of day to determine when the canopy was a source and when it was a sink of atmospheric nitrogen. Data was also analyzed in conjunction with precipitation and tree species recordings to determine whether these have an effect on deposited nitrogen and, in turn, on atmospheric nitrogen. A significant trend in nitrate concentrations throughout the day was found and involved decrease of leaf nitrate in the morning, changing to accumulation in the afternoon. This is suspected to be due to photolysis rates and the converion of nitric acid to nitrous acid and subsequent volatilization of nitrous acid.<br/><br/>Description: REU http://hdl.handle.net/2027.42/62027 Title: Back trajectory analysis: air parcel histories and forest pollutant exposure<br/><br/>Authors: McNeal, Fred<br/><br/>Abstract: Population, land cover, and regional pollutant emissions were analyzed for each of the five flow regimes indentified at UMBS in order to assess the pollutant levels for arriving air masses. The results show that the south/southwest and east/southeast flow regimes display the highest levels of NOx, CO, and anthropogenic VOC exposure (in terms of kilograms/square kilometer/ozone season day(OSD)) while the north/northwest and northeast flow regimes display the lowest. NOx, CO, and anthropogenic VOC exposure levels were estimated to be 18.0, 82.0, and 14.0 kg/km2/OSD, respectively, for the south/southwest flow regime; 10.2, 57.4, and 9.3 kg/ km2/OSD, respectively, for the east/southeast flow regime; 6.9, 29.5, and 5.0 kg/ km2/OSD, respectively, for the west flow regime; 0.8, 3.8, and 0.5 kg/km2/OSD, respectively, for the northeast flow regime; and 0.4, 1.8, and 0.3 kg/ km2/OSD, respectively, for the north/northwest flow regime. Pollution exposure levels were estimated for back trajectories according to the anthropogenic emissions (known point and area sources) for each flow regime as a whole. This method of assessing pollutant exposure was then compared with a finer-scale treatment that follows an individual trajectory. The comparison showed the coarse-scale treatment can result in both underestimates and overestimates of pollutant exposure depending on the trajectory’s path.<br/><br/>Description: REU http://hdl.handle.net/2027.42/62026 Title: Analysis of glyoxal concentrations among a deciduous forest canopy<br/><br/>Authors: Johnson, Erik D.<br/><br/>Abstract: This study demonstrated a clear distinction between the observed concentrations of glyoxal above a deciduous forest canopy when compared with concentrations collected below the canopy. Further directions for research could include the quantitative identification of factors such as ambient air mixing patterns, differences in isoprene production rates, and studies on UV radiation and aerosols within the canopy, all of which may relate to the observed discrepancy between above and below canopy measurements. Other work could could focus on further model development to calculate the concentrations of glyoxal one would anticipate seeing in different types of canopies and at different levels of the canopy itself.<br/><br/>Description: REU