The effects of nitrogen deposition on the carnivorous pitcher plant, Sarracenia purpurea

           I recently had a lecture on the effects of Nitrogen deposition on the northern pitcher plant, Sarracenia purpurea.  Through the burning of fossil fuels and the use of synthetic fertilizers, nitrogen oxides, nitrate and ammonium levels have risen over the past 100 years.  This has had an adverse effect on many different plant species, carnivorous species in particular.  Changing nitrogen deposition has led to changes in northern pitcher plants on both individual and population levels.

            Northern pitcher plants are perennials found in low-nitrogen peat bogs.  With a lifespan of 30-50 years, they live for an extremely long time in terms of most herbaceous plants.  Because of their low-nitrogen environment, pitcher plants rely on capturing arthropods in their water-filled pitchers as a source of nitrogen.  In fact, they aren’t the only species that rely on these arthropods; there is an entire community of insects and spiders that live inside of the pitcher plant’s pitcher. 

            To determine the effects that increased nitrogen levels had on the pitcher plant, my professor designed two separate experiments to compare the effects of anthropogenic nitrogen and nitrogen derived from prey species.  Through these experiments, he found that anthropogenic nitrogen led to changes in growth and morphology.

            The first experiment was centered on adding nitrogen and phosphorus to the plants anthropogenically.  It was found that instead of focusing energy on building their pitchers, pitcher plants exposed to larger amounts of nitrogen and phosphorus had larger phyllodia, which are their photosynthetically active leaves, and less shapely pitchers. The change in pitcher shape also led to lower levels of prey intake.  Additionally, they showed an increase in flowering probability.

            The second experiment that was executed was to test the effects of increasing nitrogen via prey intake. For this experiment, it was found that increasing nitrogen had no effects on the morphology of the pitcher plant.  These 2 experiments along with other studies have led people to believe that pitcher plants are now being limited nutritionally by phosphorus instead of nitrogen.

            The levels of nitrogen and phosphorus that pitcher plants are exposed to from a young age has also led to a decrease in juvenile survivorship, as well as lower population growth rates. This has made the population increasingly unstable; recent estimates have suggested that with not change to current nitrogen and phosphorus levels, the pitcher plant will likely be extinct within 650 years. If nitrogen levels continue to rise, that date could decrease to less than 100 years. 

            What must be considered is that pitcher plants aren’t the only plant species effected by rising nitrogen levels, and it is important that we realize the danger that many ecosystems as a whole face in the coming years.

lecture powerpoint:

http://www.uvm.edu/~ngotelli/Bio%20264/Pitcher%20Plant%20Lecture.pdf