“Experimental plantations such as this have not been installed since the 1980s,” said Kim Steiner, professor of forest biology, who planted the 400 or so black walnut tree seedlings as a provenance or common garden trial. “These trials were big, expensive and required serious contributions of time and resources from collaborators — and they were slow to yield publishable results. Not surprisingly, they are out of fashion.”
But provenance trials — comprised of tree seeds imported from a wide geographical range — are designed to yield valuable information about adaptation of tree populations to their environments that cannot be discovered through modeling simulations or from DNA analyses, added Laura Leites, associate research professor of quantitative forest ecology, who is currently responsible for the Black Walnut Provenance Study.
The Penn State experiment, conducted in the College of Agricultural Sciences, enables researchers to evaluate 36 tree populations from the entire black walnut geographic range, which covers much of North America. These populations have been subjected to a spatial change in climate so researchers can study how they respond.
Each population, Leites explained, presumably is adapted to the climate of seed origin and has been subjected to a different magnitude of climate change when transferred to University Park.