ESA: Ecosystem on a leaf
Ecologists often study succession in communities. That is, after a disturbance like a fire or windstorm or, indeed, even volcanic eruption, plants and animals re-colonize the site in predictable patterns. But why wait for a fire, when you can just wash your hands or wait for a brand new leaf to emerge from a tree? Voila, a blank slate for microbes of various kinds to colonize—and quickly.
“There has been a huge amount of work on plant community succession studied from an ecological perspective,” says Noah Fierer. “And food scientists have studied how food rots, but that’s it.”
Until now. Fierer is running several different projects studying microbial succession on surfaces including new leaves, which emerge from a tree as “sterile or close to sterile” according to Fierer, and the palms of undergraduates.
In the leaf experiment, Fierer and Co. visited the same plains cottonwood tree from leaf out until leaf fall, from May until end of September to see what microbes lived on it when. “Some people had speculated that it was going to be random,” says Fierer, but he showed that it looked a lot like succession on a larger scale, with recognizable early, mid and late succession community patterns.
“We are confirming 19th century ecology,” says Fierer. “At a coarse level of resolution, microbial succession is not different from macrobial succession.”
There are hundreds of microscopic species per leaf, and the details of what they are doing there are still vague. “The next step is to figure out are the early colonizers physically different than the midstage colonizers, and why they switch,” says Fierer. “I think they are responding to changes in leaf physiology, but I’m not sure.”
If I had Fierer's tools, I would track succession on a laptop keyboard from box-opening to first anniversary, or maybe on decomposing apples in different environments: urban gutter, shady woods, bobbing in the ocean, or in my shoes...once you start thinking about it, the neat experiments to run are endless.
