Does a nutrient gradient in Mud Lake Bog affect the leaf color polymorphism of pitcher plants (Sarracenia purpurea)?

Abstract

Bogs are very important, yet very threatened, ecosystems that provide many ecosystem services such as being carbon sinks, filtering pollutants, and acting as flood barriers. Because bogs have low levels of nutrients some plants in bogs have evolved carnivorous diets in order to supplement growth; the purple pitcher plant (Sarracenia purpurea) is an example of a carnivorous plant and is the organism we studied. We conducted our study at Mud Lake Bog in Cheboygan County, Michigan. We wanted to find out if there was a nutrient gradient extending from the lake into the bog, with higher concentrations of nutrients at the edges of the bog and lower nutrients in the middle, and whether the nutrient gradient we expected to find was correlated to pitcher plant redness; we expected to see more red pitchers in areas with lower nutrients because the redder the pitcher is the more insects it catches. We marked a 70 m by 40 m transect and used a 1 m2 quadrat every 10 m in the transect. We assessed pitcher plant redness and took water samples in each quadrat to assess nutrients. Our results showed that there was a significant nitrate gradient, but no gradient with respect to the other nutrients we measured. There was no correlation between percent redness of pitcher plants and the nitrate gradient. The nitrate gradient is most likely related to trees which are present at the high concentrations of nitrate. Understanding bogs well is critical to protecting them from further threats.