The researchers are the first to study the genetic framework of communities and ecosystems in the wild. They have planted several experimental "common gardens" of cottonwoods in Arizona and Utah. The trees are propagated at NAU's research greenhouse. Through DNA fingerprinting, the scientists know the precise genetic makeup of each tree.
In one experiment, Whitham's group worked with the Bureau of Reclamation to plant about 10,000 trees at the Cibola National Wildlife Refuge along the lower Colorado River, about 20 miles south of Blythe, Calif., to examine how genetic diversity at the stand level influences communities and ecosystem processes.
"The Bureau of Reclamation gets restoration out of this project, and we get this incredible experiment," said Whitham.
All of the experiments, so far, have exceeded the researchers' expectations. "Initially we thought that the [genetic influences] would be more localized--that the influences would be less genetic and more environmental as we moved beyond the local common garden setting to all of the western U.S." In the end, however, Whitham said, "Plant genes are far more important than we ever expected them to be."
Now the researchers want to know if their findings hold true in different environments around the world. "To understand how important something is, you have to test in multiple locations," Whitham said.
A parallel study in Australia that examines the eucalyptus tree as the foundation species is yielding the same results as the studies on cottonwoods. And Whitham has just returned from South Africa and Borneo in Southeast Asia, where he is planting the seeds for further study.