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The northern pitcher plant (Sarracenia purpurea) was the focus of a study by ecologists affiliated with the National Science Foundation Harvard Forest Long-Term Ecological Research site in Massachusetts. Researchers found that the water-filled pool within a pitcher plant is a tiny ecosystem whose inner workings are similar to those of a full-scale water body.
The study investigated the factors that cause some lakes and ponds to shift from clear, oxygen-rich states to irreversible green sludge. Those green ponds have passed a critical threshold, called a "tipping point"--a situation in which an ecosystem experiences a shift to a new state, with significant changes to biodiversity. Until now, the mechanisms behind those tipping points were poorly understood.Image credit: Aaron M. Ellison, Harvard Forest
