Tiny Ecosystems in Bowels of Carnivorous Plants

For insight into complex ecological dynamics, one Harvard University biologist peers into the cupped leaves of carnivorous pitcher plants.

At the bottom of each slippery-sided leaf is a pool of water into which unlucky insects fall and drown. The bugs sustain not only the plant, but an intricate food web of bacteria, plankton and invertebrates. Each pool is small enough to fit in a shot glass, and big enough to model the world.

According to the scientist, each leaf is its own "individual lake, its own individual ecosystem. Suddenly, in a bog I can walk to from my office, I’ve got 50,000 lakes to do experiments on. This is an opportunity to understand how a complete, functioning natural ecosystem works.”

Understanding how ecosystems work is an important but challenging task for scientists. Though patterns can be described — nutrient levels shift, an animal population grows, another shrinks — it can be hard to know what’s coincidental and what’s linked.

If researchers can run experiments on an ecosystem, measuring exactly what goes in and out, tweaking different aspects and seeing what happens, then they can better decipher its underlying rules.

However, it’s not easy to replicate nature. Ecologists have had some success studying islands and lakes, which are fairly self-contained, and extrapolating those findings to the rest of the natural world.

For the last fifteen years, scientists slogged through the bogs of New England, studying the life that exists in each pool. At the very base are bacteria, which support phytoplankton and cytoplankton, which support single-celled animals, which support fly larvae. All of it relies on nutrients delivered by drowning bugs.

There are four or five trophic levels in a pitcher plant, just like there are four or five trophic levels in a lake.

Fly larvae are the top-level predator in the pitcher, the analogues of tigers or wolves. They’re what ecologists call a “keystone” species, who control the abundance every other species, but require a habitat of sufficient size to support those other creatures.

Original article here.