Forest dance on wires depicts a creeping fungal multitude blown back by a tornado
Plant biology PhD student Uma Nagendra of the University of Georgia, Athens, wins the 2014 Dance Your PhD competion, sponsored by Science, AAAS, and HighWire Press.
Floating on trapeze wires, young white pine seedlings unfurl and reach for light. But lurking in the roots of the parent tree are dangerous fungi that creep forth to strike at the young scions. The sprouts closest to the great tree falter and wilt, giving ground to other plants. But lo! a tornado approaches…
Nagendra tells the story of the dance in the video notes:
The dance begins in an undisturbed forest. Because trees live for so long in one place, a mature pine tree accumulates a unique group of fungi around its roots—including pathogens that cause diseases in tree seedlings (in this case, Pythium and Rhizoctonia). White pine seedlings that are very close to a mature tree are more likely to be attacked by these pathogens—causing stunted growth, or even death. The farther away a seedling is from a mature tree, the less likely it is to get infected. These distant seedlings are more likely to survive to maturity. A pattern emerges where the mature pine trees are spaced far apart—leaving room for seedlings of other species to grow, and creating a diverse forest.
In the middle of the dance, we witness the tornado—and how it changes the forest environment. The mature pine tree dies, and the forest floor is no longer shaded. The soil becomes hotter and drier. Without the living mature tree as a host, specialist pathogens are less active, and many die. Because of this, I am predicting that plant-soil relationships in recently tornado-damaged areas may be much weaker. In the last part of the dance, seedlings close to the (killed) mature tree are no longer at greater risk for disease; they grow and survive the same as their more distant siblings. The changing plant-soil relationships after disturbances might be one piece in the puzzle of how diverse ecosystems change over time.
Read more about the competition and watch more science dancing at Science.