Effects of experimental storm surge and sedimentation on pitcher plants (Sarracenia) in a coastal pine savanna

Background/Question/Methods

Sea-level rise and stronger hurricanes associated with global climate change will likely result in farther reaching storm surges. These surges may begin transporting nutrients and salt water to nutrient poor, low saline pine savannas. Purple pitcher plants (Sarracenia purpurea) are pine savanna inhabitants that could potentially be at a disadvantage because their pitcher morphology and stout structure may leave them prone to collecting saline water and sediment after a surge. Furthermore, Sarracenia may respond to soil nutrient increases by shifting away from a carnivorous morphology (i.e. a pitcher form) to a more photosynthetically conducive morphology. We hypothesize that the combination of saline water inundation and sedimentation will cause significant pitcher plant mortality and/or surviving pitcher plants will change their morphology in response to increased soil nutrients. Plots (each containing ≥1 genet of S. purpurea) were established in pine savanna and half received saline while the other half received fresh experimental storm surge treatments. Sediment (regular, fertilized, or local soil) was randomly applied to both the ‘saline’ plots and the ‘fresh’ plots. Controls were left unburied. We documented pitcher plant percent cover, made dimensional measurements of pitchers, and collected soil samples before surging. Short term pitcher plant mortality was later assessed.

Results/Conclusions

The preliminary results indicate that saline water inundation and sediment burial (both fertilized and unfertilized treatments) resulted in significantly higher pitcher plant mortality than the control (fresh water only) treatments. However, the mortality caused by the other treatment combinations did not differ significantly from the control plots. Interestingly, many of the plots showed evidence of resprouting within three weeks. In fact, even some of the plots that experienced the most damaging treatments (i.e. saline water inundation and sedimentation) showed signs of resprouting. Such resprouting indicates that even though the above-ground structures of most of these plants senesced after surging, some of the below-ground structures were left intact. This response seems similar to pitcher plant responses to fire. As of now, though, it is unknown whether or not these genets will experience full recovery and if they will actually benefit from this disturbance in the same way that they do with fire. Our data already show that storm surges can have dramatic short term effects on S. purpurea survival and indicate that global warming may indirectly contribute to the further decline of southeastern purple pitcher plant (Sarracenia purpurea) populations in the future.